recent geology and geomorphic history of central coastal

Louisiana State UniversityLSU Digital Commons

LSU Historical Dissertations and Theses Graduate School

1955

Recent Geology and Geomorphic History ofCentral Coastal Louisiana.Jack Richard Van lopikLouisiana State University and Agricultural & Mechanical College

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RECLLT GEOLOGY Ai:D GLOMOidiilC HISTORY OF

GEhTRAL COASTAL LOUISIANA

A T h e s i s

S u b m i t t e d t o

t h e G r u d u a te F a c u l t y

L o u i s i a n a S t a t e U n i v e r s i t y and

A g r i c u l t u r a l a n d M e c h a n i c a l C o l l e g e

I n P a r t i a l F u l f i l l m e n t

o f t h e R e q u i r e m e n t s f o r t h e D e g re e o f

D o c t o r o f P h i l o s o p h y

i n

The D e p a r t m e n t o f G e o lo g y

ayJ a c k R.' Van L o p ik

U . S . , Iw ich igun S t a t e C o l l e g e , 1950 M . S . , L o u i s i a n a S t a t e U n i v e r s i t y , 1953

J u n e , 1955

EXAMINATION AND THESIS REPORT

Candidate: Jack Van Loplk

Major Field: Geology

Title of Thesis: Recent Geology and Geomorphic H istory o f Central C oastal Louisiana

Approved:

Major Professor and Chairmi

Dean

EXAMINING COMMITTEE:

Date of Examination:

May 7 . 195?

Z t e u -

Ye m a r s h e s , how c a n d i d and s i m p l e and n o t h i n g - w i t h h o l d i n g a n d f r e e Ye p u b l i s h y o u r s e l v e s to t h e s k y a n d o f f e r y o u r s e l v e s t o t h e s e a l

The i l a p s h e s o f G l y n n . IV 6 S i d n e y L u n i e r ( 1 8 4 2 - 1 8 8 1 )

i i

ACIOtfOY/LEDGIul&T

T h i s a c c o u n t i s t h e r e s u l t o f t h e w r i t e r ’ s a s s o c i a

t i o n w i t h a n i n v e s t i g a t i o n o f " T r a f f i c a b i l i t y and n a v i g a

b i l i t y o f L o u i s i a n a C o a s t a l T l a r s h e s , " a s t u d y c o n d u c t e d by

t h e S c h o o l o f G e o lo g y a t L o u i s i a n a S t a t e U n i v e r s i t y u n d e r

t h e a u s p i c e s o f t h e O f f i c e o f n a v a l R e s e a r c h , C o n t r a c t L 7

o n r 3 5 6 0 8 , T ask O r d e r i'R 088 002-. The s u r v e y w as c o n d u c t e d

d u r i n g a p e r i o d e x t e n d i n g fror.i J u n e , 1951 t o J a n u a r y , 1954*

A p p r o x i m a t e l y t h i r t e e n m on ths v /ere s p e n t i n the f i e l d c o l

l e c t i n g d a t a ; t h e r e m a i n i n g m o n th s w ere d e v o t e d t o o r g a n i s a

t i o n o f m a t e r i a l and l i b r a r y r e s e a r c h w h i l e e n r o l l e d a t

L o u i s i a n a S t a t e U n i v e r s i t y . S e v e r a l s h o r t f i e l d t r i p s w ere

a l s o made d u r i n g t h e a c a d e m ic i n t e r v a l s .

O b v i o u s l y i t w ou ld be i m p o s s i b l e t o r e q u i t e a l l t h e

a s s i s t a n c e r e c e i v e d b o t h i n the f i e l d a n d i n t h e o f f i c e

d u r i n g a p r o j e c t o f t h i s l e n g t h . N e v e r t h e l e s s , i n t h e f o l

l o w i n g p a r a g r a p h s an a t t e m p t w i l l be n u d e t o a c k n o w l e d g e ,

a t l e a s t i n p a r t , t h e h e l p a f f o r d e d f r o m t h e b e g i n n i n g o f

f i e l d w o rk t o t h e f i n a l e d i t i n g o f t h e r e p o r t .

The summer o f 1951 v/us d e v o t e d t o a g e n e r a l r e c o n

n a i s s a n c e o f s o u t h e r n L o u i s i a n a . U r . J a m e s 1 . M o r g a n , F i e l d

S u p e r v i s o r and A s s i s t a n t p r o f e s s o r o f G e o lo g y , L o u i s i a n a

S t a t e U n i v e r s i t y , w as i n c h a r g e o f o p e r a t i o n s . D r . R i c h a r d

J . R u s s e l l , P r o j e c t D i r e c t o r and Dean o f t h e G r a d u a t e S c h o o l ,

i i i

i v

L o u i s i a n a S t a t e U n i v e r s i t y ; D r . F r e d B. I C n i f f e n , Hoad o f t h e

D e p a r t m e n t o f O e o y ra p h y a n d A n t h r o p o l o g y , L o u i s i a n a S t a t e

U n i v e r s i t y ; and D r . C l a i r A. Brov/n , I r o f e s s o r o f B o t a n y ,

L o u i s i a n a S t a t e . U n i v e r s i t y , a c c o m p a n ie d t h e f i e l d p a r t y a t

v a r i o u s t i m e s a n d f u r n i s h e d i n f o r m a t i o n c o n c e r n i n g d i f f e r e n t

a s p e c t s o f c o a s t a l r e s e a r c h .

I.Tr. L ew is I ' i c h o l s an d t h e w r i t e r were c n y u y ed i n a c

c u m u l a t i n g d a t a on t h e m u d f l a t s o f U o u t h v o s t L o u i s i a n a d u r i n g

F e b r u a r y , m a r c h , A p r i l , a nd l iny o f 1 9 5 2 . I n f o r m a t i o n c o l

l e c t e d h a s b e e n i n c o r p o r a t e d i n T e c h n i c a l D e p o r t h o . 2 , Con

t r a c t M7 o n r 3 5 6 0 8 , T a s k O r d e r LB 088 0 0 2 , o f t h e O f f i c e o fV

-♦

L a v a l He s e a r oh . h r . B o b e r t Dan o s a s s i s t e d t h e v / r i t e r

t h r o u g h o u t t h e summer o f 1 9 5 2 .

i l e s s r s . Cl us ’..‘a t e m a n , B o b e r t l ’,w_ c r t c u , ' ' -ark D ix o n ,

an d ’L i l l i a n l-u*a»e s e r v e d u s a s s i s t a n t s a t v a r i o u s t i n e s u u r -

i n y J u n e , J u l y , and A u r u s t o f 1953 .

L o s e r s . Bun'ard O r t o n , F r a n k ' ‘e 1' e r , B o y e r B a u c i e r a n d

D r . Un. l i c l u t i r e , I n s t r u c t o r , D w p a r tm c n t o f G e o g r a p h y and

A n t h r o p o l o g y , L o u i s i a n a S t a t e U n i v e r s i t y , a c c o j i p n n i e d t h e

w r i t e r i n t h e f i e l d un s e v e r a l o c c a s i o n s .

H r . Honor I’uyio i* , b o a t o p e r a t o r and c h e f e x t r a o r d i

n a i r e o f J - o r r y , L o u i s i a n a , n u d e t h e f i e l d s e s s i o n s a l m o s t

e n j o y a b l e .

D i s c u s s i o n s w i t h p r o j e c t ^ e r s a n n u l r e l a t i n g t o

v a r i e u s p r o b l e m s o f t e n p r o v e d i n for;.in a] ve a n d e a i f y i n g , The

c o n t r i b u t i o n s o f Dr. v.V .. l i c l n t i r e ( c o n c e r n i n g t h e a n t h r o p o

l o g i c a l ch rono lo tsy o f s o u t h e r n L o u i s i a n a ) ; h r . F r a n k " ' e l d e r ,

( d e a l i n g v/itl; t h e m e c h a n i c s o f s t r e a m d i v e r a i o n s e n d d e l t a

f o r m a t i o n ) ; a n d U r . j Robert T r e a d w e l l ( on t h e m ac ro - and

D i i o r o - p o l e o n t o l o o y o f d e l t a i c a r e a s ) w ere p a r t i c u l a r l y

h o i p f u l .

h r . C h a r l e s K o lb , C orps o f b n - i n c e r s , ' / a t e r u u y s

E x p e r i m e n t S t a t i o n , V i e k s b u r ^ , m l . - s i f j s i p p i ; h r . f e d G ' L e i l ,

C h i e f , F u r D i v i s i o n , L o u i s i a n a D e p a r tm e n t o f V’i l d L i f e and

F i s h e r i e s , Lev/ O r l e a n s , L o u i s i a n a ; b r . L. .... b n c i . e i l , Corps

o f E n g i n e e r s , Lev; Or loan;; •Kr.-uc. D i s t r i c t H e a d q u a r t e r s , Lev;

O r l e a n s , L o u i s i a n a ; and i ' r . T'omer L au yh , L o u i s i a n a D e p a r t

ment o f H ig h w a y s , b a t o n hr u ^ e , l o u i r i a n a , made a c c e s s p o s s i

b l e t o t h e f i l e s o f t h e i r r e s p e c t i v e o r g a n i z a t i o n s . i.Ii*.

Kolb . .as e s p e c i a l l y c o o p e r a t i v e in s u c h p r o c e e d i n g s ana h i s

p a r t i c i p a t i o n i n d i s c u s s i o n s c o n c e r n i n g t h e a r e a i n v e s t i

g a t e d a l s o p r o v e d v a l u a b l e .

The s t a f f s o f oho L o u i s i a n a Room n t L o u i s i a n a S t a t e

U n i v e r s i t y and t h e L o u i s i a n a S t a t e U n i v e r s i t y D e p a r tm e n t o f

A r c h i v e s and i : a n u s c r i ; ' t s ’..’e r e o f ^ r e a t a s s i s t a n c e i n c e r t a i n '

p h a s e s o f t h e i n v e s t i g a t i o n .

D r a f t i n g f o r t h e r e p o r t uns a b l y e x e c u t e d by L o s e r s .

U o^er L a u c i e r a n d 'Thomas P o o l e .

Dr. L . V. L o v e , D i r e c t o r o f t h e S c h o o l o f G e o lo g y ,

L o u i s i a n a S t a t e U n i v e r s i t y , D r . R. J . R u s s e l l , a n d D r . J . 1 .

v i

Morgan r e v i e w e d th e m a n u s c r i p t and :;*ade s e v e r a l welcomed

c o n t r i b u t i o n s and comments . Dr . Morgan was e s p e c i a l l y h e l p

f u l i n t h i s r e s p e c t .

To t h e above m e n t i o n e d i n d i v i d u a l s a n d many o t h e r s

n o t s p e c i f i c a l l y c i t e d t h e ' w r i t e r w i s h e s t o e x p r e s s L i s m o s t

s i n c e r e a p p a ' e c i a t i o u .

TABLE OF CONTENTS

PAGE

INTRODUCTION................................................................................................ 1

AREA IN V E S T IG A T E D ................................................................................. 6

L o c a t i o n and C l i m a t e .................................................................. 6

H i s t o r y ..................................................................................................... 10

A g r i c u l t u r e and n a t u r a l R e s o u r c e s .................................... 14

PHYSIOGRAPHY....................... 21

P r a i r i e T e r r a c e ............................................................. 21

S a l t Done3 31

N a t u r a l L e v e e s ................................................................................. 32

B e a c h e s and C h e n i e r s .................................................................. 37

m a r s h l a n d s ........................................................................................... 50

L a k e s a n d B a y s ............................................. 56

DRAINAGE CiiARACFERIBTICS.................................................................. 65

P r a i r i e T e r r a c e D r a i n a g e ........................................................ 65

M a r s h l a n d D r a i n a g e ....................................................................... 67

D e p th s o f M a r s h l a n d S t r e a m s ................................................... 70

E f f e c t s o f Man-Made S t r u c t u r e s on D r a i n a g e . . . 74

GEOLOGIC HISTORY OF THE A R E A ........................................................ 77

Age o f S e d i m e n t s E x p o s e d ........................................................ 77

O r i g i n o f t h e P r a i r i e S u r f a c e .............................................. 84

O r i g i n o f t h e R e c e n t S u r f a c e .............................................. 91

Bayou S a l e ' S y s t e m ............................................................... 95

v i i

TAGE

Bayou C y p r e m o r t ....................................................................... 112

Bayou Teche and V e r a i l i o n .............................................. 123

SHORELINE FLUCTUATIONS AND THLIR SION I F I C/I, CE

AS INDICATED 131 TI1E CLLnlLRS OF VEEInlLIGN DANISH 139

MODERN CONDITIONS AND TRENDS IN CENTRAL

COASTAL L O U I S I A N A ....................................................................... 156

POSSIBLE EFFECTS OF MODERN SEA LEVEL RISE

ON COASTAL LOUISIANA.................................................................. 160

S m i i A R Y ........................................................................................................... 169

SELECTED BIBLIOGRAPHY....................................................................... 176

LIST OE TABLES

TABLE PAGE

I . V e g e t a t i o n Types o f C e n t r a l C o a s t a l L o u i s i a n a 27

i x

LIST OF PLATES

PIATE PAGE

I . I m p o r t a n t S t a g e s i n t h e D e v e l o p m e n t

o f C e n t r a l C o a s t a l L o u i s i a n a ............................................. 175

a . E a r l y a nd L a t e S a l e ’ S t a g e s

b . C y p r e m o r t S t a g e

c . L u t e T e c L e - M i s s i s s i p p i S t a g e

d . P r e s e n t

x

LIST OF FIGURES

FIGURE PAGE

1 . Map S h o w in g L o c a t i o n o f S t u d y A r e a a n d

N o r t h e r n Zone o f L e a s I n t e n s e F i e l d V.ro r k . . . 7

2 . C e n t r a l C o a s t a l L o u i s i a n a ................................................. 13

3 . D i a g r a m m a t i c I l l u s t r a t i o n o f M a r s h l a n d

P h y s i o g r a p h y a n d C o a s t a l S e d i m e n t s ..................... 22

A. P h y s i o g r a p h i c Map o f C e n t r a l C o a s t a l L o u i s i a n a 23

5 28

a . G r a i n S i z e R a n g e s o f G u l f B e a c h ,

P r a i r i e T e r r a c e , a n d N a t u r a l L ev ee

D e p o s i t s

b . G r a i n S i z e A n a l y s e s - Mudl’l a t S e d i m e n t s

c . G r a i n S i z e A n a l y s e s - B o t to m S e d i m e n t s

6 . A v e r y I s l a n d R e g i o n ................................................................ 29

7 . N a t u r a l L e v e e s o f B ay o u S a l e * ...................................... 35

8 41a . D e t a i l P h o t o g r a p h o f ’' C o f f e e - G r o u n d "

M a t e r i a l F l a n k i n g t h e E a s t e r n S h o r e

o f V e r m i l i o n Bay

b . Bayou Mouth P r a c t i c a l l y C l o s e d b y

" C o f f e e - G r o u n d " A c c u m u l a t i o n s - E a s t

e r n S h o r e o f V e r m i l i o n B ay .

x i

FIGURE

9 . ...... .......................................................................................................

a . View L o o k in g S h o r e w a r d f r o m T ip o f

O y s t e r R e e f o f f C h e n i e r l a C r o i x

b . L o o k in g G u l f w a r d a l o n g R e e f Shown i n

F i g u r e 9 a . The O n ly L iv e O y s t e r s

Found F e r e T oday Are L e a r t h e O u l f -

w ard P J x t r e n i t i e s o f t h e R e e f .

1 0 . C h e n i e r a u T i g r e R e g io n ..........................................

11 . G raph Sh o w ing F l u c t u a t i o n s i n S a l i n i t y

o v e r a Ten T e a r P e r i o d i n T y p i c a l

B r a c k i s h a n d F r e s h h a r s h A r e a s .

1 2 ...............................................................................................................

a . I l o t o f A v e r a g e W id th t o L a x i n u n

D e p t h f o r n i t e r F a a i n s o f a

II u n i a C o a s t

b . 1 - lo t o f A v e r a g e W id th t o F a x ini uni

Duptl i o f S e v e n t e e n L a k e s L a v i n g

A v e r a g e W i d t h s o f L e s s Than Two

L i l e s

1 3 . I ' r e s e n t D r a i n a g e F o l l o w i n g P l e i s t o c e n e

’A a n d e r S c a r s - S o u th o f A b b e v i l l e . .

1 4 ...............................................................................................................

a . Bayou J o e A c o u in P r o f i l e s

b . O y s t e r Bayou r ' r o f i l e s

c . Bayou Chene L r o f i l e s

X i i i

FIGURE RAGE

d . F i g u r e I l l u s t r a t i n g E r o s i o n and

D e p o s i t i o n i n T i d a l S t r e a m s

1 5 ............................................................................................................... 8'<t

a . S c h e m a t i c R e p r e s e n t a t i o n o f a

P o r t i o n o f t h e Q u a t e r n a r y H i s t o r y

o f t h e L o n n r M i s s i s s i p p i A l l u v i a l

Va 11 ey

t>. G e n e r a l i z e d S t r u c t u r a l R e l a t i o n

s h i p s o f t h e i l i s s i s s i p p i A l l u v i a l

’/ a l l e y .

c . L o n g i t u d i n a l 3 e c t i o n . . o f R e c e n t De

p o s i t s F i l l i n g L u te ’.W iscons in

m i s o i s s i p p i T r e n c h

d . C r o s s S e c t i o n o f W e s t e r n S i d e o f

La t e 'W is c o n s in i . i i s s i s s i p i . i T r e n c h

16. P l e i s t o c e n e H i s s i s s i p p i a n d Red R i v e r

l . leande r S c a r s i n S o u t h C e n t r a l

L o u i s i a n a ......................................................................... 85

1 7 . L u te P l e i s t o c e n e G e o l o g i c H i s t o r y

o f S o u t h L o u i s i a n a .....................................................87

I S ...................................................................................................................92

a . I d e a l i z e d B l o c k D ia g ra m S n o w in g

T y p i c a l S e q u e n c e o f D e p o s i t s F i l l

i n g -Lite W i s c o n s i n T r e n c h

x iv

FIGURE PAGE

b . A p p r o x i m a t e Time E q u i v a l e n c y o f

S u s c e s t o d P h y s i o g r a p h i c and C u l

t u r a l C h r o n o l o g i e s f o r t h e Lower

L l i s s i s s i p p i A l l u v i a l V a l l e y

1 9 . R e l a t i v e S i z e o f T e c h e - T i s s i s s i p p i ,

Bayou C y p r e m o r t , and Bayou S a l e '

L e v e e s ........................................................................ 98

2 0 . L o c a t i o n s o f n e v e u P r o f i l e s

Shown 011 F i g u r e 1 9 ......................................... 99

2 1 . S a l e ’ - T u c h e J u n c t i o n A r e a ................................... 101

22 . D i a g r a m m a t i c C r o s s S e c t i o n o f a

Bayou S a l e ’ L e v e e .......................................... 105

2 3 . C r o s s S e c t i o n s o f a P o s s i b l e Bayou

C y p r e n o r t ^ E x t e n s i o n .................................... 116

2A. C y p r e m o r t - T e c h e J u n c t i o n A r e a . . . . 120

2 5 . E v o l u t i o n o f t h e Upper V e r m i l i o n I t i v e r 129

2 6 . S u b s u r f a c e C o n t o u r map - Top

o f P l e i s t o c e n e .................................................... 132

2 7 ....................................................................................................... 142

a . B e a c h and C h e n i e r P r o f i l e s

b . B e l l e I s l e C r o s s S e c t i o n s

2 8 . L o c a t i o n o f P r o f i l e s Shown on

F i g u r e 2 7 a ................................................................... I 43

XV

FIGUKE PAGE

2 9 . R i v e r S e q u e n c e C h a r t s Show ing

E f f e c t s o f P o s t u l a t e d D e i t u i c

S h i f t s on t h e V e r m i l i o n 1 - a r i s h

S h o r e l i n e .............................................................. 145

3 0 . E v o l u t i o n o f t h e V e r m i l i o n P a r i s h

C h e : . i o r C o m x ; l e x ............................................... 149

3 1 . S h o r e l i n e C h an g es i n t h e P e c a n

I s l a n d - C L e n i e r a u R i g r e R e g io n

B e tw een I S 06 a n d 1 9 5 1 ............................... 152

3 2 . P o s t u l a t e d E f f e c t s o f a F i f t e e n -

F o o t R i s e i n Sea L e v e l on

C o a s t a l L o u i s i a n a .......................................... I 65

a . Modern C o a s t a l P l a i n

b . A r e a s t h a t Mould lie F l o o d e d b y

a F i f t e e n - F o o t R i s e i n Sea L e v e l

c . A r e a s t h a t Y/ould Be F l o o d e d b y

a F i f t e e n - F o o t R i s e i n Sea L e v e l

i f C o n t i n u i n g M i s s i s s i p p i R i v e r

S e d i m e n t a t i o n I s C o n s i d e r e d .

ABoTicACT

D u r i n g t h e -Q u a te rn a ry g r e a t c h a n g e s h a v e o c c u r r e d i n

c o a s t a l L o u i s i a n a . T he p r o c e s s e s g i v i n g r i s e t o t h e s e

c h a n g e s a r e s t i l l o p e r a t i v e t o d a y . Such m o d i f i c a t i o n s a r e

r e f l e c t e d i n t h e s e d i m e n t s l a i d down d u r i n g a n y g i v e n t im e

s p a n . I n t h i s s t u d y a n a t t e m p t i s m ade , p r i m a r i l y t h r o u g h

t h e i n t e r p r e t a t i o n o f t l i o s e d i m e n t a r y r e c o r d , t o r o u g h l y

o u t l i n e t h e h i s t o r y o f c e n t r a l c o a s t a l L o u i s i a n a d u r i n g t h e

p r e c e d i n g 1 5 0 , 0 0 0 y e a r s . E m p h a s i s i s p l a c e d on t h e c h a n g e s

o f t h e l a s t 5 , 0 o 0 y e a r s .

An o m n i p r e s e n t f a c t o r i n t h e i n t e r p r e t a t i o n o f t h e

h i s t o r y o f c e n t r a l c o a s t a l L o u i s i a n a i s t h e s h i f t i n g p o s i

t i o n o f t h e a n c e s t r a l M i s s i s s i p p i l i i v e r . A f t e r s t u d y i n g

t h e c h a r a c t e r i s t i c s a nd d e p o s i t s o f t h e p r e s e n t M i s s i s s i p p i ,

i t i s p o s s i b l e t o a s s i g n a n c i e n t s e d i m e n t s t o p o s i t i o n s r e l a

t i v e t o t h e p r e v i o u s l y e x i s t i n g m a j o r s t r e a m s . Thus b o r i n g s

a r e o f g r e a t i m p o r t a n c e i n d e t e r m i n i n g a n c i e n t e n v i r o n m e n t s

a n d t h e t h e n e x i s t i n g c o a s t a l c o n f i g u r a t i o n s . A c u l t u r a l

c h r o n o l o g y , b a s e d on I n d i a n a r t i f a c t s , h a s p r o v e n v e r y h e l p

f u l i n e s t a b l i s h i n g t h e r e l a t i v e a g e s o f v a r i o u s s t r e a m s .

I n a d d i t i o n , s u r f i c i a l e v i d e n c e , a s i n d i c a t e d on a e r i a l

p h o t o g r a p h s , i s o f t e n o f v a l u e i n d e t e r m i n i n g t h e mode o f

o r i g i n o f v a r i o u s s u r f a c e s , e s t a b l i s h i n g t h e r e l a t i v e a g e s

o f s t r e a m s , and i n t r a c i n g o l d s t r e a m c o u r s e s . A c o m b i n a t i o n

x v i

x v i i

o f b o r e h o l e i n f o r m a t i o n , c u l t u r a l e v i d e n c e , a n d s u r f i c i a l

e x p r e s s i o n t h u s e n a b l e s a f a i r l y c o m p l e t e p i c t u r e o f a n c i e n t

c o n d i t i o n s a n d c h a n g e s t o b e d r a w n .

Deep b o r i n g s i n d i c a t e , t h a t e n t r e n c h m e n t o f t h e G u l f

C o a s t s t r e a m s , a nd s u b s e q u e n t r e f i l l i n g o f t h e t r o u g h s , h a s

o c c u r r e d t w i c e w i t h i n t h e l a s t 1 5 0 , 0 0 0 y e a r s . T h i s e n -

t r e n c h m e n t and r e f i l l i n g was a r e s u l t o f m a j o r f l u c t u a t i o n s

i n s e a l e v e l c a u s e d by e x p a n s i o n a n d c o n t r a c t i o n o f p o l a r

i c e s h e e t s . S h a l l o w b o r i n g s , c u l t u r a l e v i d e n c e , and s u r

f i c i a l e x p r e s s i o n m akes i t p o s s i b l e t o d e c i p h e r much o f t h e

co m plex p h y s i o g r a p h i c h i s t o r y o f c e n t r a l c o a s t a l L o u i s i a n a

s i n c e t h e f i l l i n g o f t h e m o s t r e c e n t t r e n c h e s . I n a d d i t i o n ,

s i m i l a r e v i d e n c e p l u s t h e p o s i t i o n o f f o r m e r b e a c h e s makes

i t p o s s i b l e t o f o r m u l a t e a s e q u e n c e o f M i s s i s s i p p i R i v e r

d e l t a s h i f t s d u r i n g t h e l a s t 2 , 5 0 0 y e a r s .

I t i s h o p e d t h a t t h e m e th o d s u s e d i n i n t e r p r e t i n g t h e

h i s t o r y o f t h i s r e g i o n w i l l f i n d a p p l i c a t i o n i n s i m i l a r

d e l t a i c a r e a s t h r o u g h o u t t h e w o r l d .

INTRODUCTION

T h is i n v e s t i g a t i o n i s p r i m a r i l y c o n c ern ed w i th t h e

h i s t o r y o f s e d i m e n t a t i o n , and th e r e s u l t i n g p h y s i o g r a p h i c

e x p r e s s i o n s and c h a r a c t e r i s t i c s , o f a p o r t i o n o f c o a s t a l

L o u i s i a n a .

In a s t u d y o f t h i s ty p e a c c u r a t e maps and c h a r t s a r e

o f t h e utm ost im p o r ta n c e . Department o f E n g in ee r Q uadrangles ,

U n ite d S t a t e s G e o l o g i c a l Survey s h e e t s o f 1935 , U n i te d S t a t e s

C oast and G e o d e t ic Su rvey c h a r t s , and a e r i a l p h oto gra p h s o f

th e a r e a ( f l o w n dur ing A p r i l and May o f 1951) were e x t e n s i v e l y

em ployed . Hand-auger b o r i n g s , s t r e a m p r o f i l e s , l e v e l l i n e s ,

e t c . , were a c c u r a t e l y l o c a t e d on a e r i a l p h oto g ra p h s ( s c a l e o f

1 : 2 3 , 6 0 0 ) w h i l e in t h e f i e l d . L a te r t h e s e l o c a t i o n s were

t r a n s f e r r e d t o o f f i c e c o p i e s o f Department o f E n g in ee r Quad

r a n g l e s or U n i t e d S t a t e s G e o l o g i c a l Survey s h e e t s . A s e p a r a t e

f i l e card was then prepared f o r e a c h b o r e - h o l e ( a p p r o x i m a t e l y

300 i n t h e a r e a ) o r p r o f i l e ; numbered, and f i l e d a c c o r d i n g t o

q u ad ran g le l o c a t i o n . F i e l d n o t e s were t r a n s c r i b e d and r e v i s e d

t o form a r e l a t i v e l y c o h e r e n t and c h r o n o l o g i c a l r e c o r d o f th e

i n v e s t i g a t i o n . A e r i a l p h otog ra p h s ( f lo w n in t h e s p r i n g o f

1953) a t a s c a l e o f 1 : 4 0 , 0 0 0 were used in t h e c o n s t r u c t i o n o f

s e v e r a l e x t e n s i v e m o s a i c s . A e r i a l o b l i q u e s f lo w n d u r i n g th e

s p r i n g o f 1952 f a c i l i t a t e d l o o a t i o n o f such s h o r e l i n e f e a t u r e s

a s o y s t e r r e e f s and m u d f l a t s . Comparison o f o l d c h a r t s w i t h

r e c e n t maps i n d i c a t e d many i n t e r e s t i n g changes i n s h o r e l i n e

p o s i t i o n ; s i z e o f i s l a n d s ; w id th o f bayous; d e p t h s o f l a k e s ,

b a y s , and bayou s; and a r e a l e x t e n t o f v a r i o u s w a t e r b o d i e s .

B o a t s were e s s e n t i a l in most f i e l d o p e r a t i o n s . A

f o u r t e e n - f o o t wooden s k i f f powered by an o u tb oa rd motor was

u sed e x t e n s i v e l y . The s k i f f , e a s i l y la u n ch ed by two men, was

t r a n s p o r t e d on a s m a l l b o a t t r a i l e r p u l l e d by a j e e p or

c a r r y a l l . On numerous o c c a s i o n s a t h i r t y - s e v e n f o o t , s h a l lo w

d r a f t ( 3 - 3 1 / 2 f e e t ) c a b in c r u i s e r was em p loyed . A sm a l l

b o at was s t i l l n e e d e d , how ever, a s many water b o d i e s were t o o

s h o a l t o a l l o w n a v i g a t i o n w i t h t h e l a r g e r b o a t . Some b a y o u s ,

c a n a l s and l a k e s c o u ld be n a v i g a t e d o n l y in a p i r o g u e . Walk

in g a c r o s s t h e marsh, w h i l e n o t p l e a s a n t , i s p o s s i b l e and in

many c a s e s n e c e s s a r y .

H igh , f i r m ground was t r a v e r s e d i n a j e e p o r c a r r y a l l .

Many f i r m t r a c t s , n o t a c c e s s i b l e by r o a d , were r ea c h e d by

b o a t and examined on f o o t or h o r s e b a c k . Marsh b u g g i e s and

h e l i c o p t e r s a r e i d e a l f o r marsh work; how ever , t h e i r e x tr e m e

l y h ig h r e n t a l f e e s were i r r e c o n c i l a b l e w i t h t h e p r o j e c t

b u d g e t .

D r i l l i n g equipm ent c o n s i s t e d o f a s p e c i a l l y d e s i g n e d

b i t (Morgan and M c l n t i r e , ? ) , s e v e r a l fo u r and e i g h t f o o t

l e n g t h s o f t h r e e - q u a r t e r i n c h g a l v a n i z e d s t e e l p ip e ( t h r e a d

ed a t both e n d s ) , numerous p ip e s l e e v e s (u s e d t o c o n n e c t t h e

s e c t i o n s ) , and two or t h r e e e i g h t e e n i n c h p ip e w r e n c h e s . The

b i t was f a b r i c a t e d by w e l d i n g a l l / 2 i n c h s h i p a u g e r ( a b o u t

e i g h t e e n i n c h e s i n l e n g t h ) t o a 2 1 / 2 f o o t l e n g t h o f t h r e e -

q u a r t e r i n c h g a l v a n i z e d p i p e w h ic h was t h r e a d e d a t t h e o p p o s

i t e en d . G r in d in g pro du ced a more d e s i r e a b l e b e v e l and a

f i n e r c u t t i n g edge w hich f a c i l i t a t e d d r i l l i n g i n s h e l l . T h is

a u g e r h a s proven s u p e r i o r , in most r e s p e c t s , t o t h e p o s t - h o l e

or b u c k e t - t y p e a u g e r p r e v i o u s l y used i n marsh work.

By r o t a t i n g t h e p i p e w i t h t h e w r e n c h e s u n t i l a p p r o x i

m a t e l y one f o o t o f h o l e was made, a good core was u s u a l l y ob

t a i n e d . D i f f i c u l t y in e x t r a c t i n g the p ip e was e x p e r i e n c e d i f

c o r i n g was a t t e m p t e d f o r more than a f o o t and o n e - h a l f a t one

t in ie . In f a c t , when d r i l l i n g i n f i r m , h i g h l y t e n a c e o u s

c l a y s i t i s n o t a d v i s a b l e t o make more than o n e - h a l f or

t h r e e - q u a r t e r s o f a f o o t o f h o l e per i n s e r t i o n . Sample r e

c o v e r y was n o t good i n sand or s h e l l ; how ev er , th e d r i l l e r

can " f e e l " t h e s e m a t e r i a l s when e n c o u n t e r e d in t h e h o l e .

P r o b in g ( s i m p l y p u s h i n g t h e a u g e r down) t h r o u g h f a i r l y s o f t

homogeneous l a y e r s and c o r i n g t h e f i r m z o n e s proved s a t i s f a c

t o r y i n many c a s e s . Sam ples .were exam ined i n t h e f i e l d and

n o t e s w ere taken r e g a r d i n g the a p p ro x im a te p l a s t i c i t y , g r a i n

s i z e , w a te r o o n t e n t , d e g r e e o f c o m p a c t io n , o r g a n i c c o n t e n t ,

c o l o r , and d e g r e e o f o x i d a t i o n . A s m a l l hand l e n s was v e r y

h e l p f u l i n making t h e e x a m i n a t i o n s . On t h e b a s i s o f t h e s e

o b s e r v a t i o n s t h e d e p o s i t i o n a l e n v iro n m en t o f t h e sample c o u l d

o f t e n be d e t e r m i n e d . E c o l o g i c a l s t u d i e s o f t h e m acro- and

m i c r o - f a u n a o f t h e c o a s t a l r e g i o n w ou ld be e x t r e m e l y h e l p f u l

i n t h i s p h a s e o f t h e work a s c e r t a i n f a u n a l a s s e m b l a g e s

s h o u l d c h a r a c t e r i z e d e f i n i t e e n v i r o n m e n t s and c o n d i t i o n s . A

d e f i n i t e a t t e m p t s h o u l d be made t o u t i l i z e m i c r o - p a l e o n t o l o g y

more f u l l y i n a n y f u r t h e r p r o j e c t s c o n c e r n i n g d e l t a i c r e g i o n s .

Equipment was a v a i l a b l e f o r s o u n d in g ba y o u s and w a te r

b o d i e s , t a k i n g b o t to m s a m p l e s , r u n n i n g l e v e l l i n e s , and

m e a s u r in g s a l i n i t y . S o u n d in g s were made w i t h a w e i g h t e d l e a d

l i n e . An o r d i n a r y , l o n g h a n d l e d , k i t c h e n p o t f i r m l y s e c u r e d

t o an e i g h t f o o t wooden p o l e pro ved t o be a v e r y e f f e c t i v e

b o t to m s a m p l e r . A c l a m - s h e l l t y p e d r ed ge w as u t i l i z e d i n o b

t a i n i n g bo t to m sa m p le s i n d e e p e r w a t e r . A dumpy l e v e l was

e m ployed i n r u n n in g e l e v a t i o n s and d e t e r m i n i n g d i s t a n c e s

a c r o s s r e l a t i v e l y f i r m ground . The t r e m b l i n g c h a r a c t e r o f

t h e m a rsh , h o w ev e r , r e d u c e d t h e a c c u r a c y o f a t r i p o d mounted

l e v e l a s a n y n e a r b y movement would d i s t u r b t h e " s e t . ” T h e r e

f o r e , a hand l e v e l was e s s e n t i a l , and s u f f i c i e n t l y p r e c i s e ,

f o r m ost marsh work. O c c a s i o n a l l y s a l i n i t y r e a d i n g s were

taken w i t h s a l i n i t y h y d r o m e t e r s , but f r a g i l e equ ip m en t o f

t h i s t y p e n e v e r s u r v i v e d many f i e l d t r i p s .

Had a d d i t i o n a l f u n d s been a v a i l a b l e a few o b s t a c l e s

c o u l d have been a l l e v i a t e d o r e l i m i n a t e d . One d i f f i c u l t y

f a c e d t h r o u g h o u t t h e p r o j e c t , was t h e l u c k o f equ ipm ent c a p a

b l e o f d r i l l i n g r e l a t i v e l y deep (1 0 0 f e e t ) h o l e s . The n eed

was a c u t e l y f e l t i n h i g h , f i r m a r e a s w h ere e v en a t h i r t y f o o t

hand a u g e r h o l e was a h e r c u l e a n and t im e consu m in g t a s k .

C u rren t v e l o c i t y m e t e r s c o u l d have b e e n u t i l i z e d and t h e em

p i r i c a l d a t a c o l l e c t e d a p p l i e d to t h e o r i e s c o n c e r n i n g t i d a l

c h a n n e l f o r m a t i o n and f l o w , c l o s i n g o f c r e v a s s e c h a n n e l s and

o t h e r r e l a t e d p r o b le m s . As p r e v i o u s l y p o i n t e d o u t , an e c o l o

g i c a l s t u d y made c o n c u r r e n t l y w i t h t h e i n v e s t i g a t i o n would

have been o f trem en d o u s v a l u e . F o r t u n a t e l y , fu n d s were a v a i l

a b l e f o r t h e r u n n i n g o f o v e r 150 g r a i n - s i z e a n a l y s e s . The

m a j o r i t y o f t h e s e a n a l y s e s w ere o f b e a c h m a t e r i a l s , and w i l l

p r o b a b l y be i n c o r p o r a t e d i n a t e c h n i c a l r e p o r t d e a l i n g w i t h

th e b e a c h e s o f L o u i s i a n a .

AREA INVESTIGATED

L o c a t io n and C l im a te

The a r e a c o v ered i n t h i s r e p o r t e x t e n d s w estw ard from

the A tc h a l ’a l a y a R iv e r (9 1 d e g r e e s , 15 m in u t e s w e s t l o n g i t u d e )

t o t h e v i c i n i t y o f White Lake ( a p p r o x i m a t e l y 92 d e g r e e s , 30

m i n u t e s w e s t l o n g i t u d e ) , and i s r o u g h l y bounded on the n o r th

by t h e 30 d e g r e e s , 5 m inute n o r t h p a r a l l e l o f l a t i t u d e

( F i g . 1 ) . Some f i e l d work was n e c e s s a r y a s f a r n o r t h a s 30°

2 5 ’ n o r t h l a t i t u d e , how ever . The a rea i n v e s t i g a t e d , embrac

i n g a p p r o x i m a t e ly 3 ,0 0 0 square m i l e s , i n c l u d e s t h e p a r i s h e s

o f I b e r i a and S t . Mary, th e g r e a t e r p a r t o f V e r m i l io n P a r i s h ,

and p o r t i o n s o f L a f a y e t t e and S t . M art in P a r i s h e s . F irm,

t i l l a b l e l a n d c o m p r i s e s a p p r o x im a t e ly o n e - q u a r t e r o f t h i s

a r e a or a b o u t 750 square m i l e s . The rem ainder c o n s i s t s o f

m a rsh es , swamps, and w a ter b o d i e s o f v a r i o u s d i m e n s i o n s . To

a L o u i s i a n i a n , c o n t r a r y to w id e sp r e a d b e l i e f and a c c e p t e d

d i c t i o n a r y d e f i n i t i o n s , marsh and swamp a r e n o t synonymous.

As R u s s e l l ( 1 9 3 6 , pp . 2 4 - 2 5 ) has p r e v i o u s l y p o i n t e d o u t , a

marsh i s a s a t u r a t e d r e g i o n s u p p o r t i n g g r a s s e s , s e d g e s , r u s h

e s , and s i m i l a r v e g e t a t i o n , r a t h e r than t r e e s . To d e s e r v e

t h e d e s i g n a t i o n o f swamp t h e dominant growth o f a w a te ry area

must be a r b o r o u s .

I t s s u b t r o p i c a l l a t i t u d e and p r o x i m i t y to t h e G u lf o f

7

FIG. 1 MAP SHOWING LO CA T IO N O F S T U D Y AREA AND NO RTH ERN ZONE OF L E S S INTENSE FIELD WORK.

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NORTHERN LIM IT O F F IE L D WORK

NEW O RL E A N S*4

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|fA R £ A '''b ? 'S T U D Y20S C A L E - M IL E S

M exico a r e t h e two m ost im p o r t a n t f a c t o r s i n d e t e r m i n i n g t h e

c l i m a t e o f t h i s r e g i o n . J a n u a r y a v e r a g e t e m p e r a t u r e i n t h i s

zo n e i s 53«9 d e g r e e s F a h r e n h e i t ; t h a t o f J u l y , 8 1 . 8 d e g r e e s .

The number o f f r o s t f r e e d a y s a v e r a g e s 270 p e r y e a r . The

m arin e t r o p i c a l i n f l u e n c e i s o b v i o u s when one c o n s i d e r s t h a t

t h e a v e r a g e w a t e r t e m p e r a t u r e s o f t h e G u l f a l o n g i t s n o r t h e r n

s h o r e r a n g e s from 64 d e g r e e s F a h r e n h e i t i n F e b r u a r y t o 84 d e

g r e e s i n A u g u s t .

In summer t h e p r e v a i l i n g s o u t h e r l y w in d s p r o v i d e a

m o i s t , t r o p i c a l c l i m a t e . The a v e r a g e a n n u a l p r e c i p i t a t i o n i s

5 7 . 8 6 i n c h e s and o f t h i s amount a p p r o x i m a t e l y 62 per c e n t

f a l l s i n th e i n t e r v a l e x t e n d i n g from A p r i l t h r o u g h S e p te m b e r .

J u l y and A u g u s t are t h e w e t t e s t months w i t h a v e r a g e m o n th ly

p r e c i p i t a t i o n o f 8 . 0 8 and 6 . 0 5 i n c h e s r e s p e c t i v e l y . Much o f

t h i s p r e c i p i t a t i o n i s i n th e form o f a f t e r n o o n th u n d e r s h o w e r s

w h ic h o c c u r a l m o s t d a i l y d u r i n g c e r t a i n p e r i o d s o f t h e summer

m o n th s . H owever , when t h e p r e s s u r e d i s t r i b u t i o n i s a l t e r e d

s o a s t o b r in g w e s t e r l y or n o r t h e r l y w i n d s , p e r i o d s o f h o t t e r

and d r i e r w e a th e r o c c u r i n t h e u s u a l l y m o i s t summer.

In t h e c o l d e r s e a s o n t h e r e g i o n i s a l t e r n a t e l y su b

j e c t e d t o t r o p i c a l a i r and c o l d e r c o n t i n e n t a l a i r , i n p e r i o d s

o f v a r y i n g l e n g t h s . Though warmed by i t s southw ard j o u r n e y ,

t h e c o l d o c c a s i o n a l l y b r i n g s l a r g e and r a t h e r su dd en d r o p s i n

t e m p e r a t u r e . R e l a t i v e l y c o l d , southw ard f l o w i n g w a t e r upon

r e a c h i n g t h e warmer w a t e r s o f t h e G u l f h e l p s p r o d u ce t h e f o g

s o t y p i c a l o f the m a r s h la n d s d u r i n g th e w i n t e r m o n th s . A l

though t h e r e c o r d s f o r s o u t h w e s t L o u i s i a n a a r e f a r from com

p l e t e , i t a p p e a r s t h a t J a n u a r y and F e b r u a r y a r e t h e f o g g i e s t

m o n th s . * In an a r e a s u c h a s c o a s t a l L o u i s i a n a where s h o r e

l i n e s s t r e t c h h u n d re d s o f m i l e s a t an e l e v a t i o n o f l e s s th a n

f i v e f e e t above s e a l e v e l , and where t e n f e e t o f r e l i e f i s n o t

found w i t h i n 25 o r 50 m i l e s o f t h e c o a s t , a low l y i n g h a z e

can be v e r y t r o u b l e s o m e .

A l th o u g h t h i s r e g i o n se ldom e x p e r i e n c e s s t o r m s o f a

l a r g e c y c l o n i c c h a r a c t e r , i t i s o c c a s i o n a l l y v i s i t e d by w in

t e r s to r m s w h ic h u s u a l l y app ro ach from t h e n o r t h or n o r t h

w e s t . L o c a l s t o r m s o f s m a l l a r e a have o c c u r r e d i n a l l

s e a s o n s , b u t show somewhat more f r e q u e n c y i n s p r i n g . Now and

t h e n , u s u a l l y d u r i n g Septem ber o r O c t o b e r , a h u r r i c a n e w i l l

d e s t r o y l a r g e p o r t i o n s o f t h e low l y i n g , e a s i l y ero d ed m arsh

l a n d s . A t h r e e y e a r p e r i o d r a r e l y p a s s e s w i t h o u t t h e v i s i t a

t i o n o f one o f t h e s e a w e - i n s p i r i n g s to r m s a l o n g t h e L o u i s i a n a

c o a s t .

Y/h i le a d m i t t i n g t h e c l i m a t e i s r e l a t i v e l y e n j o y a b l e ,

t h e w r i t e r , n e v e r t h e l e s s , b e l i e v e s t h a t Mr. T. W. P o o l e

( 1 8 9 1 , p . 10) was c a r r i e d away w i t h a r t i s t r y when he s t a t e d ,

’’W e l l m ig h t one d i l a t e a t l a r g e on t h e l a r g e , l u c i o u s , i n n o

c e n t , s o o t h i n g n a r c o t i s m o f g u l f a i r s , b u t s p a c e f o r b i d s . ”

N e e d l e s s t o s a y , Mr. P o o l e was employed by t h e s t a t e o f

L o u i s i a n a a s Im m ig r a t io n Com m iss ioner a t t h e t ime t h e above

literary gem was penned,

History1

The region embracing the parishes of Iberia, Lafayette,

St, Mary, St, Martin, and Feimilion, was formerly known as 2

the Attakapas district or country, A name derived from a

tribe of Indians, supposedly cannibalistic, who once occupied

this region, Colorful accounts of their eating habits are

found in the literature. Perrin (1891, p, 217) states that

their favorite repast was a stew consisting of the clam

Rangia and Homo sapiens! However, the Choctaw, Alabamon,

and the Opelousas tribes united and nearly annihilated the

Attakapas in a great battle, fought on a hill about four

miles west of the present site of St, Martinville, This mas

sacre occurred before the white settlers came into the coun

try, and by 1803 approximately 100 individuals, scattered

throughout the district, were all that remained of the once

powerful Attakapas (Sibley, 1803, p, 21),

The first reports of the area came from the Spanish

1 This section was compiled mainly from works by Oriffen (1936), Carter (1952), Carton (1933), and the St, Martin Development Board (1950),

2 This word appears in the literature as Attakapas, Attacapas, Atakapas, and Atacapas, Attakapas is the spelt ing most generally used and the form used in this report.

missionaries of Los Adaes, Some of the missionaries began

making frequent visits to the Attakapas tribe, thus indicat

ing that the anthropophagous tendencies of the Attakapas were

probably greatly exaggerated, These Spanish visitations,

however, did not result in the founding of missions, as was

usually the case with their early explorers, and not until

the French had established a trading center did the white

man's influence begin to manifest itself in the area,

The first considerable Influx of settlers began soon

after 1760, Previous to this time there were scattered over

the Attakapas region a few trappers, traders and ranchers,

This impetus to colonization was provided by the English ex

pulsion of the Acadians from Nova Scotia in 1755-56. While

scattered among the English settlements along the Atlantic

coast, these exiles were not content to be absorbed into the

hated English population and naturally turned their faces to

ward Louisiana where lived their kinsmen. Although the vast

territory of Louisiana was officially transferred to Spain in

1763, the government made numerous grants of land in Attaka

pas district to exiled Acadians between 1760 and 1770. Never

theless, according to a census taken by Governor O'Reilly, in

1769 the total population of the entire district was only

409, France regained Louisiana through the Treaty of San

Ildefonso in 1801, but did not officially take possession

until November 30, 1803. At this time the number of

12

i n h a b i t a n t s in t h e A t t a k a p a s d i s t r i c t had r e a c h e d 3 , 7 4 6 , o f

w hich 1 , 2 6 6 were s l a v e s ( S i b l e y , 1 8 0 3 , p . 2 0 ) . S i b l e y a l s o

s t a t e s t h a t a c o n s i d e r a b l e p o r t i o n o f t h e p o p u la c e was Am eri

c a n . The U n i t e d S t a t e s pu rch ased L o u i s i a n a on A p r i l 3 0 , 1803

and f o r m a l l y to o k p o s s e s s i o n on December 20 o f t h e same y e a r .

I n 1805 A t t a k a p a s County or P a r i s h was c r e a t e d , embrac

i n g a la n d a r e a o f a p p r o x i m a t e ly 3 , 5 0 0 sq u a re m i l e s . The name

was changed t o S t . M a rt in P a r i s h in 1 8 0 7 , but t h i s d e s i g n a t i o n

d id n o t r e p l a c e t h e e a r l i e r a p p e l l a t i o n in th e v e r n a c u l a r .

S t . Mary P a r i s h was f a s h i o n e d from a p o r t i o n o f S t . M art in

P a r i s h i n 1 8 1 1 , a s was L a f a y e t t e P a r i s h i n 1 8 2 3 . With t h e

c r e a t i o n o f V e r m i l io n P a r i s h in 1844 and I b e r i a P a r i s h i n

1868 t h e p r e s e n t p a r i s h b o u n d a r ie s were e s t a b l i s h e d . - * The

p o p u l a t i o n i n c r e a s e d s t e a d i l y t h r o u g h o u t t h i s p e r i o d and by

1950 had r e a c h e d 1 9 6 , 2 2 4 (com bined t o t a l p o p u l a t i o n o f S t .

M a r t i n , S t . Mary, L a f a y e t t e , V e r m i l i o n , and I b e r i a P a r i s h e s ) .

S t . M a r t i n s v i l l e , ^ known a s P o s t e d e s A t t a k a p a s d u r in g

t h e S p a n i s h r e g im e , i s t h e o l d e s t s e t t l e m e n t i n t h e r e g i o n .

A s id e from t h e A c a d ian im m ig r a n ts , the e a r l y r e s i d e n t s i n

c lu d e d many o f f i c e r s o f n o b l e French and S p a n i s h f a m i l i e s who

3 The above d a t e s sh o u ld be borne i n mind when d o i n gr e s e a r c h on t h i s a r e a . For e x a m p le , i n f o r m a t i o n c o n c e r n i n ga l l f i v e o f t h e p r e s e n t p a r i s h e s can be fo u n d i n e a r l y a c c o u n t s o f S t . M art in and S t . Mary P a r i s h e s .

^ A l l l o c a l i t i e s , w i t h i n t h e p r o j e c t a r e a , m e n t io n e d i n t h e t e x t can be found on F i g . 2 .

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14

rem ained h e r e a f t e r t h e i r a p p o i n t m e n t s had e x p i r e d . S t . Mar

t i n s v i l l e f o r many y e a r s was th e c e n t e r o f c o n s i d e r a b l e c u l

t u r e and a t one t i m e s e r v e d a s a summer r e s o r t f o r New

O r l e a n s s o c i e t y . The r e g i o n i s p e r h a p s m ost p o p u l a r l y known

from L o n g f e l l o w ' s n a r r a t i v e poem o f t h e f a i r A c a d ia n "Evange

l i n e , " ^ t h e s c e n e o f w h ic h i s l a i d p r i n c i p a l l y i n t h e A t t a k a

p a s r e g i o n . A t S t . M a r t i n s v i l l e under t h e " E v a n g e l i n e Oak,"

i n t h e y a r d o f t h e c h u rch c o n s t r u c t e d i n 1 7 6 5 , i s t h e h e r o i n e ' 3

g r a v e . Here t o o i s t h e L o n g f e l l o w - E v a n g e l i n e S t a t e Park and

Museum where v a r i o u s s o u v e n i r s o f h e r l i f e a r e on e x h i b i t i o n .

S o u th w e s t L o u i s i a n a s t i l l h a s an A c a d ia n ( s i n c e c o r r u p t e d t o

"Cajun" by t h e l o c a l i n h a b i t a n t s ) p o p u l a t i o n , d i a l e c t and a t

m osphere and t h e s e , t o g e t h e r w i t h i t s a n c i e n t s t r u c t u r e s and

l e g e n d s , make i t a v e r y i n t e r e s t i n g p l a c e t o v i s i t .

A g r i c u l t u r e and N a t u r a l R e s o u r c e s

G e n t l y r o l l i n g , g r a s s c o v e r e d p r a i r i e s a r e one o f t h e

g r e a t a t t r a c t i o n s o f t h i s r e g i o n . G r a z in g o f c a t t l e and

h o r s e s was t h e main a c t i v i t y o f t h e e a r l y s e t t l e r s . Even

t o d a y c a t t l e , in g r e a t num bers , a r e g r a z e d t h r o u g h o u t t h e

a r e a , n o t o n l y on t h e p r a i r i e l a n d s , b u t i n t h e marsh a s w e l l .

Marsh h e r d s o f a s p e c i a l b r e e d , r e q u i r i n g l i t t l e c a r e w h i l e

i n p a s t u r e , must be t r a n s p o r t e d ( u s u a l l y by b a r g e s ) t o h ig h

5 A l t h o u g h s u p p o s e d l y ba sed on f a c t , L o n g f e l l o w t o o k many l i b e r t i e s w i t h t h e o r i g i n a l s t o r y .

15

l a n d b e f o r e t h e summer m o n th s , a s c a t t l e l o s e w e i g h t r a p i d l y

when under c o n t i n u e d a t t a c k by swarms o f summer m o s q u i t o s .

In some c a s e s t h e a n i m a l s hove been k i l l e d by t h e s e i n s e c t s .

T h e ir d e a t h s , h o w ev e r , w ere b r o u g h t a b o u t n o t by b e i n g e a t e n

Hon t h e h o o f , " but r a t h e r by s u f f o c a t i o n due t o s e a l i n g o f

t h e c r a n i a l o p e n i n g s by c l o u d s o f m o s q u i t o s .

E a r l y a t t e m p t s a t a g r i c u l t u r e w e re made by t h e Span

i a r d s . About 1765 t h e S p a n i s h governm ent s e n t a c o l o n y from

t h e Canary I s l a n d s t o e n g a g e i n t h e c u l t i v a t i o n o f f l a x and

hemp (Mann, 191-^, p . 6 ) . T h i s e n t e r p r i s e proved a f a i l u r e ,

b u t i n d i g o was r a i s e d s u c c e s s f u l l y and became a s t a p l e com

m o d i t y . Some c o t t o n was a l s o p r o d u c e d , but by 1812 su g a r

cane was b eco m in g i n c r e a s i n g l y im p o r t a n t ( S t o d d a r d , 1 8 1 2 , p .

1 8 2 ) . Today s u g a r ca n e i s t h e l e a d i n g crop vvL t h abou t

9 1 , $ 0 0 a c r e s i n c u l t i v a t i o n . T h i s a c r e a g e produ ced 1 , 5 9 6 , 2 5 1

t o n s o f ca n e i n 1 9 4 8 . Of t h i s t o t a l I b e r i a P a r i s h c o n t r i

b u te d 5 7 5 , 0 8 3 t o n s ; c l o s e l y f o l l o w e d by S t . Mary P a r i s h w i t h

5 4 7 , 2 3 5 t o n s (L a n d ry , 1 9 5 ^ , P* 3 7 8 ) . R e c e n t l y r i c e h a s b e

come an e x t r e m e l y i m p o r t a n t crop in t h e s o u t h w e s t e r n p o r t i o n

o f th e a r e a . R i c e c o m p l e t e l y d o m i n a t e s t h e a g r i c u l t u r a l p i c

t u r e i n V e r m i l i o n P a r i s h t o d a y .

T r a p p in g , one o f t h e e a r l i e s t p u r s u i t s f o l l o w e d i n th e

r e g i o n , c o n t i n u e s t o p l a y a pro m in en t r o l e . M u sk ra t , n u t r i a ,

m ink, r a c c o o n and o t h e r f u r b e a r i n g a n i m a l s a r e foun d i n t h e

c o a s t a l m a r s h e s . The p r o d i g i o u s numbers o f m uskrat e n a b l e s

16

L o u i s i a n a to p rodu ce more com m erc ia l p e l t s than any o t h e r

s t a t e i n th e U n ion . The n u t r i a ( S o u t h Am erican c o y p u —

M y o ca s to r c o y p u ) was a c c i d e n t a l l y i n t r o d u c e d i n t o t h e I b e r i a

P a r i s h m a r s h la n d s i n 1937* P r e v i o u s t o t h i s t im e t h e r e were

no n u t r i a i n t h e L o u i s i a n a m a r s h e s . T h ese p r o l i f i c a n i m a l s

have m u l t i p l i e d so r a p i d l y t h a t t h e L o u i s i a n a n u t r i a t a k e f o r

t h e 1 9 4 8 - 4 9 s e a s o n was 2 6 , 7 3 8 . Many p e o p l e b e l i e v e t h e s e

r o d e n t s w i l l become one o f the m o s t v a l u a b l e f u r p r o d u c e r s

on t h e N o r t h Am erican c o n t i n e n t .

The w a t e r s o f t h e r e g i o n abound i n e d i b l e f i s h and

s h e l l f i s h . Some shrim p a r e t a k e n t h r o u g h o u t t h e y e a r , but

t h e h e a v i e s t c a t c h e s a r e made in t h e l a t e summer and f a l l .

The s h e l l f i s h i n d u s t r y h a s made r e m a r k a b le p r o g r e s s , e s p e c i

a l l y in th e l a s t t h i r t y y e a r s , from the i n a u s p i c i o u s b e g i n

n i n g s o f t h e 1 8 8 0 ' s^ t o t h e m i l l i o n d o l l a r b u s i n e s s o f t o d a y .

P a t t e r s o n and v i c i n i t y i s an im p o r ta n t shrimp l a n d i n g r e g i o n ,

c o n t r i b u t i n g t h e g r e a t e r p a r t o f t h e 1 1 , 9 9 7 , 9 3 0 pounds o f

sh r im p brough t i n t o S t . Mary P a r i s h i n 1 9 4 8 . A lm o st t h e e n

t i r e c a t c h i s t a k e n by s m a l l o t t e r - t r a w l b o a t s w h ich drag

b a g - l i k e n e t s a l o n g t h e b o t t o m . Today the b e s t s h r im p in g

w a t e r s a r e fo u n d o f f Cameron and V e r m i l io n P a r i s h e s . The

l a c k o f d e e p n a v i g a b l e w aterw ays o p e n i n g d i r e c t l y i n t o t h e

^ T h i s e a r l y f i s h i n g v/as c o n f i n e d t o t h e i n l a n d w a t e r b o d i e s . S h r im p in g i n t h e G u l f d i d n o t r e a l i z e any g r e a t im p o r ta n c e u n t i l t h e 1 9 3 0 ' s .

G u l f and t h e p r e s e n t s i z e o f t h e s h r im p in g f l e e t a re f a c t o r s

w h ic h w i l l p r o b a b ly f o r e s t a l l any g r e a t e x p a n s io n o f t h i s

f i s h e r y in th e r e g i o n . The b l u e crab i s found a b u n d a n t ly i n

t h e bays and b a y o u s ; how ev er , t h e l a c k o f l a r g e n e a r b y mar

k e t s f o r f r e s h crab has been an im p o r ta n t f a c t o r in h o l d i n g

back th e d ev e lo p m en t o f t h i s f i s h e r y . Twenty y e a r s ago o y s

t e r s f l o u r i s h e d a l o n g t h e s h o r e l i n e , und i n the i n l a n d w a t e r s

o f the r e g i o n . A r t i f i c i a l d r a i n a g e c a n a l s ( f o r t h e A t c h a f a -

l a y a B a s i n ) and t h e A t c h a f a l a y a R i v e r have b rough t i n c r e a s i n g

amounts o f f r e s h w a t e r and se d im e n t i n t o t h e a r e a . I n f l u x o f

s e d im e n t has a l m o s t d e s t r o y e d t h e o y s t e r r e e f s and t h r e a t e n s

to e x te n d d e s t r u c t i o n f a r t h e r w e s tw a r d .

W it h in t h e l a s t f o r t y y e a r s s u b s t a n t i a l o i l p r o d u c

t i o n h a s been a c h i e v e d . S t . Mary P a r i s h a l o n e produced o v e r

1 1 , 2 0 0 , OuO b a r r e l s o f p e t r o l e u m i n 1 9 4 8 , and t h e combined

t o t a l p r o d u c t i o n o f t h e f i v e p a r i s h e s was a p p r o x i m a t e l y 34

m i l l i o n b a r r e l s . The o i l u s u a l l y o c c u r s i n a s s o c i a t i o n w i t h

i n t r u s i v e s a l t m a s s e s c a l l e d s a l t domes ( s e e P h y s io g r a p h y

S e c t i o n ) . Some o f t h e s h a l l o w e s t domes a r e mined and I b e r i a

P a r i s h has t h r e e o f the l a r g e s t p r o d u c in g s a l t m ines i n the

w o r l d .

O i l a c t i v i t y h a s b ro u gh t a b o u t a n o t e w o r t h y i n c r e a s e

i n p o p u l a t i o n . The c i t y o f L a f a y e t t e , f o r e x a m p le , i n c r e a s e d

in s i z e by s e v e n t y - f o u r p e r c e n t be tw een 1940 and 1950 due

m a in ly t o t h e p e t r o l e u m i n d u s t r y .

18

A few o f the n a t u r a l r e a o u r c e s have been r u t h l e s s l y -

e x p l o i t e d . In t h i s c a t e g o r y f a l l th e lum bering and a l l i g a t o r

e n t e r p r i s e s . The e x t e n s i v e t r a c t s o f c y p r e s s and l i v e oak,

which made th e a r e a a lum ber ing bonanza in t h e l a t e 1800*s

and e a r l y 1 9 0 0 ' s , have been c u t . Sm al l saw m i l l s s t i l l o p e r

a t e i n V e rm i l io n and one or two o t h e r p a r i s h e s , but t h e c o l o r

f u l lum bering days are o f th e p a s t . A l l i g a t o r s once i n f e s t e d

the swamps and m arshes . E a r ly a c c o u n t s t e l l o f h o r d e s o f the

p u g n a c io u s r e p t i l e s c o m p l e t e l y c l o s i n g f a i r l y l a r g e bay o u s ,

thus making n a v i g a t i o n i m p o s s i b l e ( C a t h c a r t , 1 8 1 9 ) . Animals

e i g h t e e n or tw e n ty f e e t l o n g were n o t r a r e i n t h e s e e a r l y

days and ten f o o t g a t o r s were common. T h e ir d e c l i n e i s e v i

dent when one c o n s i d e r s t h a t th e a l l i g a t o r ’’take" f o r L o u i s i

ana i n t h e 1948 -49 s e a so n was 3 5 , 7 9 6 , and o n l y t h i r t y - f i v e o f

t h e s e a n im a ls were o v e r t e n f e e t i n l e n g t h . However, p r o

h i b i t i n g a l l i g a t o r h u n t in g on s e v e r a l s t a t e r e f u g e s has

brought abou t a r e v e r s a l o f t h i s d e p o p u l a t i o n i n a few s c a t

t e r e d r e g i o n s .

The f u t u r e p r o s p e r i t y o f t h i s r e g i o n seems t o depend

upon o i l , s u g a r , r i c e , and t r a p p i n g . E x p lo r a t io n f o r o i l i s

in p r o g r e s s i n a l l o f the f i v e p a r i s h e s and many new f i e l d s

w i l l u n dou bted ly be d i s c o v e r e d . Sugar cane i s the most im

p o r t a n t a g r i c u l t u r a l commodity, e s p e c i a l l y i n th e e a s t e r n

p a r i s h e s , and t h e r e seems t o be l i t t l e t e n d e n c y f o r t r a n s

f e r e n c e o f a c r e a g e t o o t h e r c r o p s . R ice i s w e l l e s t a b l i s h e d

i n th e so u t h w e s te r n s e c t o r and w i l l p ro b a b ly grow i n impor

ta n c e i f i r r i g a t i o n problems can be overcome. A g r e a t d e a l

o f w a te r i s pumped from t h e V erm il io n R iv e r d u r in g t h e l a t e

summer months f o r i r r i g a t i o n p u r p o s e s , o f t e n g i v i n g r i s e t o

t h e i n t r u s i o n o f a s a l t w ater wedge, w h ich sometimes e x t e n d s

upstream to t h e v i c i n i t y o f A b b e v i l l e . At c e r t a i n p o i n t s

t h i s s a l t water in v a d e s the g r a v e l i f e r o u s a q u i f e r s from

which o t h e r i r r i g a t i o n w ater i s pumped. As r i c e can n o t t o l e r

a t e b r a c k i s h w a t e r , r e s u l t s o f t h e s e c o n d i t i o n s can e a s i l y be

d i s a s t r o u s . S t u d i e s are being' made by the L o u is ia n a G e o l o g i

c a l Survey i n an e f f o r t to a l l e v i a t e th e s i t u a t i o n , but u n t i l

a s o l u t i o n can be a f f e c t e d th e r i c e a c r e a g e in t h i s s e c t i o n

cannot be g r e a t l y i n c r e a s e d . Trapping s e a s o n s seem to run in

c y c l e s w i t h y e a r s o f h ig h f u r p r o d u c t io n f o l lo w e d by p e r io d s

in w h ich th e c a t c h i s v e ry d i s a p p o i n t i n g . However, t h e r e

seems t o be no o v e r a l l t r e n d toward a d e c r e a s e in the number

o f f u r b e a r in g a n i m a l s . A p p l i c a t i o n o f c o n s e r v a t l o n a l p r a c

t i c e s w i l l e n a b l e t h i s a c t i v i t y to p e r p e t u a t e i t s p o s i t i o n as

an im portant sou rce o f revenue f o r t h e r e g i o n .

A lthou gh few m a n u fa c tu r in g companies have l o c a t e d

h e r e , t h e r e i s a d e f i n i t e t r e n d toward i n d u s t r i a l i n f i l t r a

t i o n . L a f a y e t t e , F r a n k l in , and New I b e r i a app ear a s p r o b a b le

c e n t e r s f o r i n d u s t r i a l growth . Another p o t e n t i a l so u rce o f

r e v e n u e , which i s by no means o v e r lo o k e d e i t h e r in t h i s

r e g i o n or L o u is ia n a a s a w h o le , i s t h e t o u r i s t . Tiib' "Cajuns"

20

o f s o u t h w e s t L o u i s i a n a a r e a c o l o r f u l and i n t e r e s t i n g p e o p l e ;

t h e i r l a n d s , w h ic h a r e fa m o u s i n h i s t o r y and l e g e n d , abound

i n f i s h and w i l d game o f many v a r i e t i e s . Wild g e e s e and

d u c k s i n p r o d i g i o u s numbers w i n t e r i n t h e m a r s h e s , t r u l y mak- .

i n g t h e r e g i o n a h u n t e r ’ s p a r a d i s e . Many p o i n t s o f i n t e r e s t

i n b o th t h e h i s t o r i c and a e s t h e t i c s e n s e a r e fo u n d h e r e .

T h ese a t t r a c t i o n s and t h e i r p r o x i m i t y t o New O r le a n s s h o u l d

p r o v i d e t h e e x p e d i e n t s to l u r e a g r e a t e r p o r t i o n o f t h e t o u r

i s t t r a d e i n t o t h e a r e a .

PHYSIOGRAPHY

A lt h o u g h t h e w r i t e r has t r i e d , i n t h e p r e c e d i n g p a g e s ,

t o p r e s e n t a b r i e f , c u l t u r a l p i c t u r e o f t h e a r e a more o r l e s s

d i v o r c e d from p h y s i o g r a p h i c a l a s p e c t s , t h e r e a d e r h a s un-

d o u b t a b l y s e n s e d t h e c o n t r o l l i n g i n f l u e n c e o f p h y s i o g r a p h y on

t h e c u l t u r a l , a g r i c u l t u r a l and e co n o m ic p a t t e r n s o f t h e

r e g i o n . The f o l l o w i n g p a r a g r a p h s , t h e r e f o r e , w i l l p r e s e n t a

f a i r l y d e t a i l e d d e s c r i p t i o n o f t h e m ajor p h y s i o g r a p h i c

r e g i o n s and f e a t u r e s found h e r e .

F i g u r e 3 i s a r e p r e s e n t a t i o n o f m arsh land p h y s i o g r a p h y

and i t s s e d i m e n t a r y r e l a t i o n s h i p s . In t h i s b l o c k diagram

many p h y s i o g r a p h i c f e a t u r e s have b e e n crowded i n t o a s m a l l

a r e a ; h o w e v e r , i t s h o u l d be r e a l i z e d t h a t m ost o f t h e m arsh

la n d a p p e a r s a s a l e v e l , s e e m i n g l y e n d l e s s , w a te r and g r a s s

p l a i n , w i t h v e r y f e w , i f a n y , r e l i e f f e a t u r e s b r e a k i n g t h e

m onoton y . A p h y s i o g r a p h i c map o f C e n t r a l C o a s t a l L o u i s i a n a i s

p r e s e n t e d a s F i g u r e

P r a i r i e T e r r a c e

F irm , a r a b l e la n d i s fo u n d on t h e P r a i r i e T e r r a c e ,

a l o n g t h e c r e s t s o f n a t u r a l l e v e e s , and on a few e x i s t i n g and

s t r a n d e d b e a c h r i d g e s . The P r a i r i e T e r r a c e , s o named by

21

DIAGRAMMATIC ILLUSTRATION OF AND C O A S TA L

UPTHRUST SALT DOI(PLEISTOCENE)

CHENIERiOLD MUDFLAT CONVERTED TO MARSH

MODERN BEACH

MUDFLATGULF OF MEXICO

i \ m B e a c h D e p o s i t s 3.|

L e v e e D e p o s i t s 4 .1 ] B ay & L a k e^ D e p o s i t s

M u d f l a t D e p o s i t s ^V //X

6.1

1 - 7 ARE RECENT II

22

I OF M ARSHLAND PHYSIOGRAPHY TAL S E D IM E N T S

KLJ DOMEPLEISTOCENE OUTCROPMARSH

ANCIENT ABANDONEDDISTRIBUTARY CANAL BANK

* N

Nl I « « l

1 !i i i l

5 .

6 .

2 * 2 C h a n n e l F i l l 7 . H 1 In t e r c a l a t i o n s o f 1 - 6

M a r s h D e p o s i t s a l i l l P l e i s t o c e n e

RECENT IN AGE

Figure 3

PHYSIOGRAPHIC MAP OF CENTRAL COASTAL LOUISIANA

PRAIRIE TERRACE

NATURAL LEVEES

MARSH

SWAMP

BEACH RIDGES

G U L F M E X I C O

SC A LE IN M ILES5 10

23SEKJB3

m

m w W m .M

£

BLANCHE

EA ST COTE

BLANCHE BAY

CrJ_S L A N

a t c h a p a L a y

Figure 4

2 k

F i s k ( 1 9 3 8 ) , i s t h e rem nan t o f a huge P le i s t o c e n e " ^ d e l t a i c

p l a i n t h a t r e a c h e d i t s maximum a r e a l e x t e n t i n t h i s r e g i o n

a p p r o x i m a t e l y 5 0 , 0 0 0 y e a r s a g o . The g e n e s i s o f t h i s s u r f a c e

w i l l be t r e a t e d i n t h e G e o l o g i c H i s t o r y s e c t i o n o f t h i s r e

p o r t . A wedge o f P r a i r i e ( F i g . k ) c o n s t i t u t e s t h e l a r g e s t

t r a c t o f s o l i d ground i n t h e r e g i o n . T h i s u n d u l a t i n g s u r f a c e

r i s e s from an e l e v a t i o n o f two f e e t (MGL) a t i t s s o u t h e r n

c o n t a c t w i t h t h e m a rsh , w h ich s t r i k e s r o u g h l y E-W, t o h e i g h t

o f n e a r l y t h i r t y f o o t n e a r Rayne and l a f a y e t t e ( F i g . 2 ) . The

main a x i s o f t h e d e l t a i c mass p l u n g e s g e n t l y S-S3W t h r o u g h

th e L a f a y e t t e a r e a , t h u s o r i g i n a l l y g i v i n g r i s e to a s l i g h t

E-ESE and a s i m i l a r w e s t e r n s l o p e away from t h e a x i a l e l e v a

t i o n s . E a s t w a r d , th e P r a i r i e T e r r a c e d i s a p p e a r s b e n e a t h th e

Recent® s e d i m e n t s n e a r B a l d w in . I n g e n e r a l , t h e P r a i r i e d i p s

v e r y g e n t l y Gulfward ( o n e and o n e - h a l f t o two f e e t p er m i l e )

and h a s a maximum r e l i e f o f a b o u t t w e n t y - f i v e f e e t . The

n o r t h e a s t e r n b o r d e r o f t h i s p l a i n h a s been s c a l l o p e d by a

R e c e n t c o u r s e o f t h e M i s s i s s i p p i R i v e r , r e s u l t i n g i n a s c a r p

t h a t i n c r e a s e s i n e l e v a t i o n n o r th w a r d . The r e l i e f shown by

t h i s s c a r p i s n e g l i g i b l e s o u t h o f J e a n e r e t t e ; t e n f e e t n e a r

New I b e r i a , and t w e n t y - f i v e f e e t a t L a f a y e t t e .

? The i n t e r v a l e x t e n d i n g from one m i l l i o n t o 2 5 , 0 0 0 - 1 5 , 0 o 0 y e a r s a g o .

8 The i n t e r v a l e x t e n d i n g from 2 5 , 0 0 0 - 1 5 , 0 0 0 y e a r s ago t o t h e p r e s e n t t i m e .

25

The p r e s e n t w r i t e r i s i n a g r e e m e n t w i t h Howe and

A lo r e s i ( 1 9 3 3 , PP« 1 3 - 1 5 ) who c o n s i d e r t h i s s c a r p t o b e p o s t -

P l e i s t o c e n e i n o r i g i n . The c u s p a t e b o r d e r o f t h e s c a r p n e a r

l a f a y e t t e c e r t a i n l y s u g g e s t s l a t e r a l p l a n a t i o n by a p o s t -

P l e i s t o c e n e A l i s s i s s i p p i R i v e r . The w r i t e r i s a w a r e t h a t t h i s

i n t e r p r e t a t i o n d o e s n o t a g r e e w i t h K e s s e l l i ' s ( 1 9 4 1 ) c o n c e p t s

o f s l o p e r e t r e a t . K e s s e l l i d e d u c e s t h a t i t i s i m p o s s i b l e f o r

a m e a n d e r i n g s t r e a m t o p l a n a t e l a t e r a l l y a g a i n s t c l i f f s much

h i g h e r th a n t h e n o r m a l n a t u r a l l e v e e s . F i e l d e v i d e n c e c e r

t a i n l y d o e s n o t s u p p o r t t h i s c o n t e n t i o n . The o n l y p o s s i b l e

a l t e r n a t e e x p l a n a t i o n f o r th e e x i s t e n c e o f t h i s c u s p a t e

s c a r p i s t o a s su m e t h a t i t was c u t by a l a t e P l e i s t o c e n e

s t r e a m t h a t c o n t i n u e d t o m ea n d er f o r a l o n g p e r i o d o f t i m e

a f t e r e n t r e n c h m e n t . T h i s h y p o t h e s i s s e e m s h i g h l y i m p r o b a b l e .

The u n d u l a t i o n s p r e s e n t on t h e P r a i r i e T e r r a c e a r e r e

f l e c t i o n s o f P l e i s t o c e n e s t r e a m d e p o s i t s . The c h a n n e l s , now

f i l l e d and o f t e n d i s c o n t i n u o u s , o f t h e s e a n c i e n t s t r e a m s

s t i l l f i n d e x p r e s s i o n i n t h e p o n d s and lo w swampy a r e a s

w h i c h d o t t h e r e g i o n . M ost o f t h e s e p o n d s , c a l l e d "M ara is"

by t h e l o c a l i n h a b i t a n t s , a r e c i r c u l a r i n o u t l i n e . R u s s e l l

h a s s u g g e s t e d t h a t t h e s e c i r c u l a r d e p r e s s i o n s a r e a r e s u l t o f

t h e c o m p a c t i o n o f s e d i m e n t s t h a t f i l l e d t h e s c o u r p o o l s

( l o c a l d e e p s i n a c h a n n e l u s u a l l y a t t h e o u t s i d e o f b e n d s ) o f

t h e b u r i e d r i v e r c h a n n e l s ( J o n e s , 1 9 5 4 , p . 7 9 ) . A l t h o u g h t h e

P r a i r i e i t s e l f i s t r e e l e s s t h e more p o o r l y d r a i n e d r e g i o n s

26

o f t e n s u p p o r t s t a n d s o f Drummond r e d m a p l e , g r e e n a s h , w a t e r

o a k , w i n g e d e l m , r e d gum, w i l l o w o a k , swamp b l a c k g u m , and

b a l d c y p r e s s (B ro w n , 1 9 4 5 , p» 1U) ( T a b l e I ) . The t y p e o f g r o w th

p r e s e n t d e p e n d s t o a l a r g e e x t e n t upon t h e l e n g t h o f t i m e

t h e s e d e p r e s s i o n s h o l d w a t e r . The i m p e r v i o u s n a t u r e o f t h e

c l a y t o c l a y - s i l t t o p s t r a t u m i s t h e m o s t i m p o r t a n t f a c t o r i n

d e t e r m i n i n g t h e t r e e l e s s c h a r a c t e r o f m o s t o f t h e r e g i o n .

T r e e s a r e a l s o fo un d a l o n g t h e n a t u r a l l e v e e s o f p r e s

e n t s t r e a m s and on r i d g e s where t h e la n d i s b e t t e r d r a i n e d .

The grow th h e r e c o n s i s t s o f w a t e r o a k , c h e r r y b a r k o a k , p o s t

o a k , g r e e n a s h , American e lm , red gum, sh a g b ark h i c k o r y , cow

o a k , ha w th orn s and l o b l o l l y p i n e ( T a b le I ) . Thus t h e t im b e r

found i n t h i s r e g i o n o c c u r s on la n d w h ic h i s e i t h e r b e t t e r

d r a i n e d or more p o o r l y d r a i n e d th a n th e P r a i r i e p r o p e r (Brown,

1 9 4 5 , p. 1 0 ) .

The e x p o se d upper p o r t i o n o f t h e P r a i r i e i s w e l l o x i

d i z e d , commonly c o n s i s t i n g o f y e l l o w i s h brown c l a y s and

s i l t s (F ig . 5 a ) . The s e d i m e n t s a r e r i c h i n c a l c i u m , and many

c a l c a r e o u s c o n c r e t i o n s a r e foun d a t and n e a r t h e s u r f a c e .

The l i g h t c o l o r o f t h i s upperm ost zone s t a n d s i n marked c o n

t r a s t to t h e d a r k e r h u e s o f t h e marsh and swamplands w h ic h

f l a n k t h e P r a i r i e T e r r a c e i n t h i s r e g i o n . T h i s c o l o r c o n

t r a s t ( F i g . 6 ) p l u s t h e a r c u a t e p a t t e r n s o f P l e i s t o c e n e mean

d er l o o p s , w h ic h c o v e r , p o r t i o n s o f t h e P r a i r i e T e r r a c e , a r e

d i s t i n c t i v e c r i t e r i a f o r r e c o g n i t i o n o f t h i s s u r f a c e on

TABLE I

VEGETATION T Y PE S OF CENTRAL COASTAL LOUISIANA

COMPILED MAINLY FROM BROWN (1 9 3 6 , 1 9 4 4 , 6 1945) AND O 'N EIL (1 9 4 9 )

•oH0

e<

4G0

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10

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l 100HX

1w

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XXXJX00XmVEGETATION TYPICAL OF:

DEPRESSIONS ON THE PRAIRIE SURFACE ■ ■ ■ ■ ■■B E TT E R DRAINEO AREA ON THE PRAIRIE SURFACE

L l l m■ 1

NATURAL LEV EES, SPOIL BANKS, a BEACH RIDGES IN FRESH MARSH AREAS

■ ■■■ ■ ■ ■ ■ i

NATURAL L EV EE S, SP O IL BANKS, 8 BEACH

RIDGES IN BRACKISH TO SALT MARSH AREAS ■ ■ ■ ■ ■ ■ i

FRESH W ATER MARSH

BRACKISH WATER MARSH

SALT WATER MARSH

■Cactus - Onuntia

1 Palmetto — Sabel tcinor

1Rlark willow - S a lix n ir ra

1Tooth—ache tr e e — Zanthoxvlum c lav a—hereu1i 3 L.

Sea oxeve — B orrlchia fra te sco n s

Sand rush — F lm b ris tv lis sastanea

Marsh e ld e r — Iva fru tesccn s L.

S a l t—matrimonv vine — Lvciuin carolinianum W alt.

■ A llin a to r weed — A lternanthera nhiloxeroiden

K l.nhant»a e a r - Colocasia antiouorun

S oft rush — .Juncus effusus

Sawerasa — Mari nrus fam aicensis

P a l l ie Fine - Panicum honitonon

Water hvacinth — Piaroous c ra ss in e s

P irk e ra l weed — Pontedoria cordata

Paddle weed — Saprittaria lan c lF o lia

Arrowhead — S acritta ria l a t i f o l i a

Rulnish — Sci rrliS validus

wat-.p m ille t - Z iian io p sia o il ia c e a

-

Reed cane — Phrainnites concunis

C a t ta i l , lance le a f — Tvnha an trust i Fol i a

C a tta i l , broad le a f — Typha la t lF o l ia

Bayonet rush — Sclrpus amerieana

Three square — Scirpus o lneyl

I«»fy three square - Scirpus robustus

Ovster c rass — S oartina a l t e m if lo r a

Rl CT rnprf trrass - Snartina cynosuroides

TCouch e ra ss — S nartina oatens

Saltw ort - B atis maritiina

I Sea oxeve - B orrichia fru te scen s

l S a lt marsh crrass — D ls t lc h l is sp lea ta

■ Sand rush - Fitnbri s t v l i s castanea

■ Black rush — Juncus roemerianus

■ S a l t—matrlmonv vine — Lvelum carolinianum W alt.

■ s a l t water a l l lp a ta r weed - Philoxerus verm icu laris

l .feinted sa ltw o rt — S a lic o m ia

■ Nendle cord p rass — S p artin a sp a rtin ae

28

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GRAIN SIZE RANGES OF GULF BEACH, PRAIRIE TERRACE, AND NATURAL LEVEE DEPOSITS

GULF BEACHVERMILION AND IBERIA PARISHES

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MUDFLAT MATERIAL (CHENIER L A CROIX)

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GRAIN SIZE ANALYSES BOTTOM SEDIMENTS

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29

F i g u r e 6 - A very I s l a n d R e g io n

a e r i a l p h o t o g r a p h s .

To anyone f a m i l i a r w i t h manual d r i l l i n g th r o u g h R e c e n t

d e p o s i t s i n t o the P l e i s t o c e n e , a d i s c u s s i o n o f how t o r e c o g

n i z e t h e c o n t a c t w i l l prove s u p e r f l u o u s . D i f f e r e n c e i n c o lo r ,

o x i d a t i o n , f i r m n e s s , and w a t e r c o n t e n t a r e u s u a l l y a p p a r e n t .

The P r a i r i e t o p s t r a t u m i s t y p i c a l l y a s t i f f , g r a y t o g r e e n i sh -

g r a y , n o d u la r ( f e r r u g e n o u s a n d /o r c a l c a r e o u s ) , s i l t y c l a y .

P r e v i o u s ex trem e o x i d a t i o n g i v e s r i s e t o t h e m o t t l e d o r a n g e -

brown and g ra y s i l t y c l a y s w h ic h f r e q u e n t l y mark t h i s c o n

t a c t . The s u r f a c e , u n d e r l y i n g t h e R e ce n t m arsh , i s m o d e r a t e

l y d i s s e c t e d and p r e s e n t s a good d e a l o f s u b s u r f a c e r e l i e f . 9

T h e r e f o r e , i t would be n a i v e t o assume t h a t t h e P ' r a i r i e t o p

s t r a t u m i s ev eryw here homogeneous and e q u a l l y o x i d i z e d . - In

f a c t , some h o l e s show no o x i d a t i o n in t h i s upper z o n e . How

e v e r , th e d i f f e r e n c e i n c o m p a c tn e s s and , h e n c e , w a te r c o n t e n t

i s o b v i o u s . The w a t e r c o n t e n t i n t h e upper zone o f t h e

P r a i r i e u s u a l l y r a n g e s from 20 t o 30?», w h e r e a s , th e d a r k e r ,

o v e r l y i n g R e c e n t marsh d e p o s i t s c o n s i s t e n t l y show more than

3 2 $ ( F i s k , 1 9 4 8 ) . The r e s u l t i n g d i f f e r e n c e i n f i r m n e s s i s

e a s i l y n o t i c e d when p u t t i n g down a bore h o l e ; i n d e e d , th e

s t i f f , t e n a c i o u s c h a r a c t e r o f t h i s zone e f f e c t i v e l y d i s c o u r

a g e s d e e p e r p e n e t r a t i o n w i t h hand a u g e r equ ip m en t .

9 The t o p o f th e P l e i s t o c e n e i s u s u a l l y e n c o u n t e r e d w i t h i n 100 f e e t o f t h e p r e s e n t s u r f a c e in t h e a r e a c o n s i d e r e d i n t h i s r e p o r t . E x c e p t i o n s t o t h i s s t a t e m e n t w i l l be p o i n t e d o u t i n th e G e o l o g i c H i s t o r y s e c t i o n .

31

S a l t Domes

With f o u r n o te w o r th y e x c e p t i o n s , t h e r e are no e x

p o s u r e s o f P r a i r i e s o u t h o f t h e l i n e m arking i t s g e n t l e

p lu n g e b e n e a th t h e R e c e n t d e p o s i t s . The e x c e p t i o n s c o n s t i

t u t e f o u r o f t h e famous "F ive I s l a n d s " o f L o u i s i a n a . T h e s e

rem arkable e l e v a t e d a r e a s , cau sed by t h e i n t r u s i o n o f l a r g e

m a s s e s o f r o c k s a l t t o w i t h i n 100 o r s o f e e t o f t h e p r e s e n t

marsh s u r f a c e , are foun d a l o n g a l i n e b e a r i n g S 4 9 c E and run

n i n g from Lake P ie g n e u r t o E a s t Bay nea r the mouth o f th e

Lower A t c h a f a l a y a R iv e r ( F i g . 2 ) . The e l e v a t i o n s o f t h e

"Five I s l a n d s " range from f o r t y to 130 f e e t above marsh l e v e l

and i n one c a s e (Avery I s l a n d ) the s a l t i t s e l f , capped by

P l e i s t o c e n e and p o s s i b l y o l d e r m a t e r i a l , i s a c t u a l l y about

f i f t e e n f e e t above t h e p r e s e n t marsh s u r f a c e . In many

r e g i o n s 130 f e e t o f r e l i e f would be c o n s i d e r e d i n s i g n i f i c a n t ;

how ever , h i l l s o f t h i s e l e v a t i o n r i s i n g f ro m a f l a t , f e a t u r e

l e s s marsh appear s p e c t a c u l a r i n d e e d .

In o u t l i n e t h e " i s l a n d s " are u s u a l l y more or l e s s c i r

c u l a r , th e l a r g e s t (Yfeeks) h a v in g a d i a m e t e r o f s l i g h t l y more

than two m i l e s . T h e ir s u r f a c e top o g r a p h y i s t y p i c a l l y rugged

and s m a l l f r e s h w ater ponds a re found i n th e d e p r e s s i o n s .

A lth o u g h o f the same s o i l ty p e a s t h e f l a t l y i n g P r a i r i e

10 J e f f e r s o n I s l a n d r i s e s from t h e P r a i r i e T erra ce i t s e l f between New I b e r i a and A b b e v i l l e ,

Terra ce t o t h e n o r t h , s u p e r i o r d r a in a g e c o n d i t i o n s g i v e r i s e

t o a heavy s ta n d o f l a r g e t r e e s o f a t y p e found o n l y under

s p e c i a l c o n d i t i o n s on t h e P r a i r i e proper (T a b le I ) . On

a e r i a l p h o t o g r a p h s , due to t h i s d en se a r b o r o u s c o v e r , t h e s e

' • is lands" app ear a s s l i g h t l y d a r k e r , s t i p p l e d , c i r c l e s and

o v a l s in th e more e v e n t e x t u r e d marsh. However, where man

has c l e a r e d the t im b e r the l i g h t c o l o r e d , o x i d i z e d , s i l t y

c l a y o f t h e P r a i r i e s t a n d s i n sh arp c o n t r a s t t o t h e surroun d

i n g marsh ( F i g . 6 ) . Where c r e s t a l c o l l a p s e o f a s h a l l o w dome

has o c c u r r e d , due to s o l u t i o n o f t h e u n d e r l y i n g s a l t , th e

s u r f i c i a l e x p r e s s i o n i s o f t e n t h a t o f a la k e ( e . g . , l a k e

P e i g n e u r ) .

N a t u r a l L e v ee s

N a t u r a l l e v e e s , which f l a n k most l a r g e s t r e a m s , are

d e p o s i t s o f f l o o d w a t e r s c r o s s i n g normal ban ks . They c o n s i s t

o f the c o a r s e s t m a t e r i a l , u s u a l l y s i l t - s i z e , c a r r i e d i n s u s

p e n s io n by t h e s t r e a m . The h i g h , f i r m , w e l l d r a in e d c r e s t s

o f t h e s e l e v e e s were a t t r a c t i v e s t r i p s f o r e a r l y s e t t l e m e n t .

I n d i a n s encamped on t h e r i d g e s a t a t im e when t h e volume o f

f r e s h w ater f l o w was g r e a t enough t o s u s t a i n t h e i r numbers.

When th e f l o w became t o o f e e b l e t h e v i l l a g e was g r a d u a l l y

abandoned and new encampments were made near o t h e r s o u r c e s o f

f r e s h w a te r . R efuge heaps (m iddens) o f t h e s e v i l l a g e s , con

s i s t i n g o f clam s h e l l s ( R a n g ia ) , p o t t e r y , and o t h e r a r t i f a c t s ,

33

a r e fo u n d a l o n g some o f t h e s t r e a m s . E a r l y w h i t e s e t t l e m e n t

i n t h e r e g i o n was c o n c e n t r a t e d a l o n g t h e l e v e e s o f th e main

a r t e r y o f t r a v e l , Bayou T e c h e . Modern r o a d s , w here p o s s i b l e ,

a r e l o c a t e d t o t a k e a d v a n t a g e o f t h e f i r m w e l l d r a i n e d land

o f th e l e v e e c r e s t . A l t h o u g h t h e n a t u r a l l e v e e d o e s n o t

d o m in a te t h e c u l t u r a l p a t t e r n a s c o m p l e t e l y a s i n t h e more

e a s t e r n L o u i s i a n a m a r s h e s , t h e y a r e , n e v e r t h e l e s s , o f g r e a t

im p o r t a n c e .

T y p i c a l l y , t h e d i s t a l p o r t i o n o f an a c t i v e s t r e a m ,

where s l i g h t s t a g e v a r i a t i o n s w i l l i n u n d a t e t h e lo w b a n k s ,

w i l l have l o w , g r a s s c o v e r e d l e v e e s . S l i g h t l y u p s tr ea m ,

where th e banks a r e h i g h e r and n o t c o n t i n u a l l y f l o o d e d , w i l

l o w s and o t h e r woody p l a n t s a r e fo u n d . F a r t h e r up stream th e

w e l l d r a i n e d and s p a s m o d i c a l l y i n u n d a t e d l e v e e s s u p p o r t

l u x u r i o u s s t a n d s o f l i v e oak ( R u s s e l l , 1 9 3 6 , p . 7 7 ) .

V/hen s t r e a m f l o w i s r e d u c e d s u f f i c i e n t l y ( t o a p o i n t

where h ig h s t a g e w a t e r f a i l s t o o v e r t o p th e b a n k s ) l e v e e

growth i s h a l t e d . With f u r t h e r r e d u c t i o n i n f l o w , c h a n n e l

d e t e r i o r a t i o n and f i l i n g t a k e s p l a c e r a p i d l y . C h ann el f i l l

u s u a l l y c o n s i s t s o f e x t r e m e l y s o f t , o r g a n i c (wood f r a g m e n t s ,

e t c . ) , b l u e - g r e y c l a y and a b a s a l zone o f c o a r s e r m a t e r i a l

( s i l t or sa n d ) c o v e r i n g t h e o l d s t r e a m b o t t o m . Com paction

and r e g i o n a l s u b s i d e n c e combine t o s l o w l y lo w e r t h e l e v e e

c r e s t s t h u s a l l o w i n g t h e m arsh to e n c r o a c h upon t h e i r f l a n k s .

Many s t r e a m s i n t h e r e g i o n ( e . g . , Bayou T e c h e , C yprem ort ,

34

and Sale*) e x h i b i t t h e e f f e c t s o f r ed u c ed f l o w and s u b s i d e n c e .

The h i g h e r , voider, n a t u r a l l e v e e s u s u a l l y a r e c l e a r e d

f o r c u l t i v a t i o n , and on a e r i a l p h o to g r a p h s t h e s e l i g h t , r e c

t a n g l e marked bands a r e e a s i l y i d e n t i f i e d where t h e y wend

t h e i r way a c r o s s th e d a r k e r m arsh . U n c le a r e d l e v e e s , w i t h

t h e i r v e r d a n t growth o f l i v e o a k , appear a s s i n u o u s , s t i p p l e d

r ib b o n s c r o s s i n g t h e more even t e x t u r e d marsh ( F i g . 7 ) . When

l e v e e growth c e a s e s , su b s id e n c e d o m in a te s and t h e marsh be

g i n s t o e n c r o a c h upon t h e l e v e e f l a n k , b r i n g i n g d e a t h t o t h e

l i v e oak o f the lo w e r l e v e l s . As s u b s id e n c e c o n t i n u e s , t h i s

zone o f e x t e r m i n a t i o n w i l l work upward toward the l e v e e

c r e s t , w h i l e the i n v a d in g marsh e f f e c t i v e l y c o v e r s th e d e c a y

i n g , f a l l e n t r u n k s in t h e lower z o n e s . T h e r e f o r e , i t i s p o s

s i b l e t h a t a d i s c o n t i n u o u s d ou b le l i n e o f oak t r e e s c r o s s i n g

t h e marsh c o u ld r e p r e s e n t a f o r m e r ly v e r y im p o r ta n t s t r e a m ,

w h e r e a s , much w id e r bands o f t r e e s m ight i d e n t i f y a more r e

c e n t , but l e s s im p o r ta n t c h a n n e l .

The w i d t h o f e x i s t i n g l e v e e s i s , t h e r e f o r e , a f u n c t i o n

o f t h e s t a g e v a r i a t i o n and s i z e o f th e d e p o s i t i n g s tream and

the amount o f coxnpaction and s u b s i d e n c e t h a t has taken p l a c e

s i n c e d e p o s i t i o n . Sm al l s t r e a m s form s t e e p , narrow l e v e e s ,

w h ereas l e v e e s o f l a r g e r s t r e a m s are g e n e r a l l y broad and

g e n t l y s l o p i n g . I n t h i s a r e a l e v e e c r e s t s se ldom r i s e more

than f i f t e e n f e e t above marsh l e v e l and i n m ost c a s e s th e

r e l i e f i s l e s s than t e n f e e t .

EAST COTE BLANCHE BAY

MARSH

OAK COVERED NATURAL LEVEES OF BAYOU SALE

/ \

F i g u r e 7 - N a t u r a l L e v e e s o f Bayou S a l e ’

35

F i g u r e 7 - N a t u r a l L e v e e s o f Bayou S a l e

36

I n t i m e t h e l e v e e c r e s t s may be c o m p l e t e l y e n g u l f e d

by t h e marsh and a l l s u r f i c i a l e v i d e n c e o f t h e i r e x i s t e n c e

o b l i t e r a t e d ( F i g . 3 ) . S i n u o u s l i n e s , o f a d i f f e r e n t shade

than t h e m arsh p r o p e r , i n a f e w i n s t a n c e s r e f l e c t submerged

l e v e e s y s t e m s . H owever , bore h o l e v e r i f i c a t i o n i s n e e d e d i n

su ch c a s e s . The t r a n s i t i o n from m arsh t o l e v e e i s u s u a l l y

i n d i c a t e d by an a b r u p t change i n t h e s t i f f n e s s o f t h e m a t e r i

a l th rou g h w h ich one i s d r i l l i n g . T h i s change i s due m a i n l y

t o th e d i f f e r e n c e i n w a t e r c o n t e n t b e tw e e n marsh and l e v e e .

The w a te r c o n t e n t o f l e v e e d e p o s i t s r a n g e s from 15 t o 25°h

w h ic h i s , a t t h e maximum v a l u e , 10a/o l e s s t h a n t h a t o f m ost

marsh m a t e r i a l . A l e v e e sa m p le t y p i c a l l y c o n s i s t s o f b l u e -

g r a y s i l t y c l a y o r s i l t ( F i g . 5a) w i t h v a r y i n g c o n c e n t r a t i o n s

o f s m a l l , brown, o x i d a t i o n n o d u l e s . The p r e s e n c e o f o x i d i z e d

n o d u l e s o r z o n e s i s u b a s i c c r i t e r i o n f o r t h e r e c o g n i t i o n o f

l e v e e m a t e r i a l in b o r e h o l e s . O rg a n ic m a t e r i a l , r a r e l y

p r e s e n t , u s u a l l y o c c u r s i n s m a l l bands or l a y e r s and i s n o t

d i s s e m i n a t e d t h r o u g h o u t th e l e v e e a s i t u s u a l l y i s i n marsh

d e p o s i t s .

From t h e ab ov e d e s c r i p t i o n some s i m i l a r i t y b e tw e e n

l e v e e and P r a i r i e T e r r a c e d e p o s i t s i s n o t e d . T h is s i m i l a r i t y

i s t o be e x p e c t e d , f o r t h e same a l l u v i a l p r o c e s s e s are o p e r a

t i v e t o d a y a s p r o d u c e d the P r a i r i e s u r f a c e o v e r 5 0 , 0 0 0 y e a r s

a g o . In bore h o l e s t h e marsh c o v e r e d P r a i r i e s u r f a c e can

u s u a l l y be d i s t i n g u i s h e d from l e v e e m a t e r i a l by i t s g r e a t e r

37

o x i d a t i o n , more t e n a c i o u s or " s t i c k y " c h a r a c t e r , and t h e

p r e s e n c e o f c a r b o n a t e n o d u l e s . In r e g i o n s where o l d , w e l l

o x i d i z e d l e v e e d e p o s i t s o v e r l a p and f l a n k t h e P r a i r i e T e r r a c e

( e . g . b e tw e e n J e a n e r e t t e and F r a n k l i n ) d i f f e r e n t i a t i o n i s

more t r o u b l e s o m e . As a c o n s e q u e n c e t h e o u t c r o p p a t t e r n o f

t h e P l e i s t o c e n e , i n s u c h a r e a s , i s d i f f i c u l t t o d e t e r m i n e .

S e v e r a l b o r e h o l e s put down by t h e w r i t e r n e a r F r a n k l i n

showed no c o n f i r m a t i o n o f F i s k ’ s ( 1 9 5 2 , v o l . 2 , p l a t e 13)

" i s l a n d " o f P r a i r i e i n t h e s u r r o u n d i n g l e v e e d e p o s i t s . H o le s

were d r i l l e d on t h e " i s l a n d " and on d e f i n i t e l e v e e m a t e r i a l ;

no d i f f e r e n t i a t i o n c o u l d be made. In t h e w r i t e r ' s o p i n i o n

m o st o f t h i s a r e a i s u n d e r l a i n by l e v e e d e p o s i t s . The p r e

s e n s e o f a r e l i c t c h a n n e l f l a n k e d by d e f i n i t e l e v e e s ( n o t

m e r e l y a t r o u g h ) r u n n i n g a c r o s s th e " i s l a n d " a l s o s u p p o r t s

t h i s c o n t e n t i o n . P l e i s t o c e n e i s u n d o u b t e d l y p r e s e n t a t a

s h a l l o w d e p t h , and a s m a l l e r " i s l a n d " than F i s k i n d i c a t e s may

be e x i s t e n t . There a r e d e f i n i t e e x p o s u r e s o f P r a i r i e a b o u t

t h r e e m i l e s to t h e n o r t h w e s t . F i s k ( 1 9 5 2 , v o l . 2 , p l a t e 1 2 c )

a l s o f a i l s to i n d i c a t e t h e l e v e e s o f Bayou Cypreraort c r o s s i n g

t h e P r a i r i e T e r r a c e s o u t h e a s t o f J e a n e r e t t e . These m inor

m o d i f i c a t i o n s o f t h e P l e i s t o c e n e o u t c r o p p a t t e r n a r e p r e s e n t e d

i n F i g . 4 .

B e a c h e s and C h e n i e r s

B e a c h e s o f v a r y i n g c o m p o s i t i o n and h e i g h t p a r a l l e l

some G u l f and bay s h o r e s i n t h e r e g i o n . In m ost c a s e s ,

m a rsh , l a c k i n g a su p e r im p o s e d b e a c h , b o r d e r s d i r e c t l y on t h e

b a y s . S i l t a c c u m u l a t i o n s o f s m a l l a r e a l e x t e n t a r e found

a l o n g t h e n o r t h w e s t e r n s h o r e s o f A t c h a f a l a y a , V/est Cote

B l a n c h e , and V e r m i l i o n B a y . Most o f t h e s e c o n c e n t r a t i o n s o f

s i l t a r e , i n p a r t , a r t i f i c i a l l y p r o d u c e d . The man-made Wax

Lake O u t l e t C h a n n e l , w h ich d r a i n s a p o r t i o n o f t h e A t c h a f a l a

y a B a s i n , s u p p l i e s some o f the s i l t s i z e d p a r t i c l e s found

a l o n g t h e n o r t h w e s t e r n sh ore o f A t c h a f a l a y a Bay . The Up-

t h r u s t i n g o f th e s a l t dome, B e l l e I s l e , has a l s o c o n t r i b u t e d

t o t h e s e d im e n t s u p p l y , n o t o n l y t h r o u g h e r o s i o n p r o d u c t s o f

t h e dome i t s e l f , b u t t h r o u g h a s h o a l i n g o f t h e o f f s h o r e p r o

f i l e , t h e r e b y i n t e n s i f y i n g t h e e r o s i v e and w in n ow in g a c t i o n

o f t h e w a v e s .

C ote B la n c h e I s l a n d has been t r u n c a t e d by t h e r e t r e a t

i n g n o r t h e r n s h o r e l i n e o f West Cote B la n c h e B ay . At t h e

p o i n t o f t r u n c a t i o n , wave a t t a c k h a s p rod u ce d a c l i f f (an

an o m a lo u s f e a t u r e i n m a r s h la n d s ) a b o u t f i f t y f e e t h i g h .

M a t e r i a l e r o d e d fro m t h e " i s l a n d " h a s formed many l o c a l i z e d

s i l t - s a n d b e a c h e s , c o n t a i n i n g g r e a t c o n c e n t r a t i o n s o f m in u te

i r o n n o d u l e s , a l o n g t h e sh o r e w estw ard from t h e " i s l a n d . "

T h i s w estw ard d r i f t i s a p p a r e n t i n t h e b a y s , a s a l o n g t h e

G u l f s h o r e , and i s , in p a r t , t h e r e s u l t o f t h e b ack e d d i e s

c r e a t e d by t h e dom inant e a s tw a r d c u r r e n t found i n t h e n o r t h

e r n p o r t i o n o f t h e G u l f o f M ex ico and t h e p r e v a i l i n g ( s o u t h

e a s t e r l y ) wind d i r e c t i o n .

39

The n o r t h w e s t e r n s h o r e o f V e r m i l i o n Bay a l s o e x h i b i t s

s e v e r a l z o n e s o f s i l t c o n c e n t r a t i o n . The s h a l l o w d e p t h o f

th e P l e i s t o c e n e ( u s u a l l y l e s s t h a n t e n f e e t ) and t h e d r e d g i n g

o f t h e New V e r m i l i o n R i v e r C ana l h a s i n f l u e n c e d s e d i m e n t a t i o n

i n t h i s a r e a t o a g r e a t e x t e n t .

Other t y p e s o f b e a c h d e p o s i t s a r e fo u n d i n t h e a r e a .

S m a l l , l o c a l i z e d , s h e l l ( p r e d o m i n a t e l y Q s t r e a a n d / o r R a n g i a )

b e a c h e s , su p e r im p o s e d on t h e m arsh , a r e e s p e c i a l l y common

a l o n g th e n o r t h e r n c o a s t o f Marsh I s l a n d and t h e w e s t e r n

sh o r e o f V e r m i l io n B ay . The e a s t e r n s h o r e o f West Cote

B la n c h e Bay i s f l a n k e d b y a b l a n k e t o f b l a c k , o r g a n i c f l a k e s

and p a r t i c l e s , w h ich r e a c h e s a t h i c k n e s s o f two f e e t a b o u t

100 f e e t o f f s h o r e . The t e x t u r e and c o l o r o f t h i s m a t e r i a l

c l o s e l y r e s e m b l e s , and i s c o n s e q u e n t l y c a l l e d , " c o f f e e

g ro und s" by t h e l o c a l i n h a b i t a n t s ( F i g . 8a ) . T h ese a ccu m u la

t i o n s are e v en g r e a t e r a l o n g t h e e a s t e r n sh o re o f V e r m i l io n*

Bay, h e r e fo r m in g s m a l l b e a c h e s and r i d g e s , w h ic h , in many

c a s e s , a l m o s t c o m p l e t e l y c l o s e th e m ouths o f s m a l l b a y o u s

d i s c h a r g i n g i n t o t h e bay ( F i g . 8b ) . T h i s t y p e o f d e p o s i t i s

o f t e n fo u n d f l a n k i n g t h e seaw ard ed g e o f m ost b e a c h e s and i s

d e r i v e d from d e c a y e d o r g a n i c r e m a i n s , o f v a r i o u s v e g e t a t i o n a l

t y p e s , w h ic h h a ve b een rew orked and thrown t h e r e by wave a c

t i o n . C o n c e n t r a t i o n s a s l a r g e a s t h o s e foun d i n s e c t o r s o f

’West Cote B la n c h e and V e r m i l i o n Bay can o n l y have t h e i r

o r i g i n i n t h e t r e m e n d o u s q u a n t i t i e s o f w a t e r h y a c i n t h

40

(P i a r o p u s c r a s s i p e s ) and a l l i g a t o r weed (A l t e r n a n t h e r a p h i l -

o x e r o i d e s ) t h a t a n n u a l l y choke t h e ba yo u s e n t e r i n g t h e s e

b a y s . From t h e s e s l u g g i s h ba y ou s much o f t h i s f r e s h w a t e r

f l o a t i n g v e g e t a t i o n f i n d s i t s way i n t o t h e b r a c k i s h , d e a t h -

d e a l i n g w a t e r s o f th e b a y .

The b e a c h e s d i s c u s s e d i n th e p r e c e d i n g p a r a g r a p h s s e l

dom r i s e more than t h r e e and o n e - h a l f f e e t above t h e mean

w a te r l e v e l o f t h e b a y s . T h i s f i g u r e i n c l u d e s t h e h e i g h t o f

th e marsh ( u s u a l l y l e s s than one f o o t ) p r o j e c t i n g above mean,

w a t e r l e v e l . In o t h e r w o r d s , t h e r e l i e f ( i n r e a l i t y t h e

t h i c k n e s s ) e x h i b i t e d by t h e s e b e a c h e s r a r e l y e x c e e d s t h r e e

f e e t . T h is i s n o t t h e s i t u a t i o n found a l o n g p o r t i o n s o f th e

g u l f c o a s t where waves o f a g r e a t e r f e t c h and power form sand

and s h e l l b e a c h e s t h u t f r e q u e n t l y r i s e to h e i g h t s o f t e n f e e t

above mean g u l f l e v e l .

The w e s t e r n c o a s t o f Marsh I s l a n d and t h e C h en ie r au

T i g r e a r e a e x h i b i t t h e m ost e x t e n s i v e b e a c h e s found i n th e

r e g i o n . Here h u r r i c a n e v/aves c a r r y beach m a t e r i a l t h r e e

q u a r t e r s o f a m i l e i n l a n d o v e r b e a c h c r e s t s t h a t a t t a i n e l e

v a t i o n s o f t e n f e e t . T y p i c a l l y , w ashover d e p o s i t s b l a n k e t

t h e marsh f o r t h r e e o r f o u r hundred y a r d s i n l a n d . The b e a c h -

3s u s u a l l y p r e s e n t a r a t h e r s t e e p g u l fw a r d s i d e and a g e n t l e

landward s l o p e .

The b e a c h e s i n th e Marsh I s l a n d - C h e n i e r au T ig r e

r e g i o n a r e composed p r i m a r i l y o f sand and s h e l l f r a g m e n t s

F ig u r e 8a - D e t a i l P hotograph o f "C offee -G roun d ’1 M a t e r i a l F la n k in g t h e P a s t e r n Shore o f V e r m i l io n Bay.

F ig u r e 8b - Bayou Mouth P r a c t i c a l l y C lo se d by "Coffee-Ground" A c c u m u la t io n s - P a s t e r n Shore o f V e r m i l io n Bay.

( F i g . 5 a ) • Some o f the c o a r s e s t sand fo u n d a l o n g t h e L o u i s i

ana c o a s t i s o b s e r v e d h e r e . These d e p o s i t s c o n s i s t o f r e

worked m a t e r i a l b r o u g h t i n from o f f s h o r e . C o n s e q u e n t l y ,

s h e l l s o f a n i m a l s c h a r a c t e r i s t i c o f many d i f f e r e n t e n v i r o n

m ents ( e . g . , m arsh , d e l t a i c , and m a r in e ) a r e found i n b ea c h

d e p o s i t s . The p r e s e n c e o f numerous o f f s h o r e o y s t e r r e e f s e x

p l a i n s t h e abundance o f O s t r e a f r a g m e n t s . The e x i s t e n c e o f

o t h e r t y p e s o f s h e l l s ( e . g . , R a n g i a , a t y p i c a l b r a c k i s h

w a t e r f o r m ) , and o t h e r d a t a , s u g g e s t s t h a t t h e s h o r e l i n e was

a t one t im e c o n s i d e r a b l y s o u t h o f i t s p r e s e n t p o s i t i o n . Com

p a r i s o n o f o l d and r e c e n t maps d e f i n i t e l y shows t h a t a l a n d

ward movement o f the s h o r e l i n e has t a k e n p l a c e , and i s c o n

t i n u i n g t o t h e w e s t i n Cameron P a r i s h .

D u ring th e p a s t f i f t y y e a r s , h o w e v e r , t h i s landward a d

vance o f t h e b ea c h h a s b een h a l t e d i n t h e C h e n ie r au T i g r e area,

i n d e e d , t h e s h o r e l i n e i s now m oving g u l f w a r d . T h is r e v e r s a l

h a s been a c c e l e r a t e d g r e a t l y w i t h i n t h e l a s t t e n y e a r s , d u r i n g

w h ic h t im e , e x t e n s i v e m u d f l a t s have form ed f l a n k i n g t h e beach .

The f l u i d c l a y , c o m p r i s in g t h e g r e a t e r p e r c e n t a g e o f t h e d e

p o s i t s ( F i g . 5 b ) , i s c a r r i e d t o t h e G u l f in s u s p e n s i o n by

s t r e a m s and c a n a l s d r a i n i n g t h e A t c h a f a l a y a B a s i n . These

s m a l l p a r t i c l e s a r e c a r r i e d w estw ard from t h e A t c h a f a l a y a Bay

r e g i o n by l o n g s h o r e c u r r e n t s and d e p o s i t e d where c o a s t a l and

b o t to m c o n f i g u r a t i o n d i c t a t e s . O y s t e r r e e f s form e f f e c t i v e

s e d im e n t t r a p s and w r e s t l a r g e q u a n t i t i e s o f su sp en d ed

43

m a t e r i a l from th e w a t e r . The i n f l u x o f s e d im e n t l a d e n f r e s h

w a t e r s c a u s e d by t h e i n c r e a s i n g d i s c h a r g e o f th e A t c h a f a l a y a

R i v e r , h a s d e s t r o y e d m ost o f th e o y s t e r r e e f s i n t h e a r e a

( F i g . 9a and b ) , and t h r e a t e n s t o e x t e n d t h i s d e v a s t a t i o n

w estw a r d .

As th e mud i s d e p o s i t e d a l o n g t h e s t r a n d , and g r a d u a l

l y i n c r e a s e s i n t h i c k n e s s t o a p o i n t where normal h i g h t i d e

d o e s n o t c o v e r t h e s u r f a c e w i t h more th a n one o r two i n c h e s

o f w a t e r , o y s t e r g r a s s ( S p a r t i n a a l t e r n i f l o r a ) i n v a d e s t h e

n e w ly formed z o n e . W ith in a y e a r , a f t e r t h e c r i t i c a l h e i g h t

h a s been r e a c h e d , t h i s g r a s s i s fo u n d c o v e r i n g t h e m u d f l a t i n

s c a t t e r e d c lumps ( S e e p h o t o g r a p h s F i g . 3 1 ) . The v e g e t a t i o n a l

c o v e r a i d s i n t r a p p i n g s e d i m e n t and so on t h e m u d f l a t i s c o n

v e r t e d i n t o .a m arsh , which i s i n u n d a t e d o n l y d u r i n g p e r i o d s

o f s t r o n g s o u t h e r l y w in d s when w a t e r i s r a i s e d t o uncommon

h e i g h t s a l o n g t h i s c o a s t . One h u r r i c a n e , h o w e v e r , can n u l l i

f y t h e work o f many y e a r s and d e s t r o y l a r g e p o r t i o n s o f t h i s

lo w , n e w ly formed l a n d . N e v e r t h e l e s s , t h e n e t e f f e c t i s

G ulfward a d v a n c e . C o n s e q u e n t l y , a s th e m u d f l a t ex p a n d s s e a

ward t h e f o r m e r beach becom es s e p a r a t e d from t h e G u l f by an

e v e r g r o w i n g band o f m arsh .

O ld , marsh s u r r o u n d e d , b e a c h e s ( f o u n d up t o n i n e m i l e s

i n l a n d ) s t a n d i n mute t e s t i m o n y to p r e v i o u s f l u c t u a t i o n s o f

t h e s h o r e l i n e . T h ese s t r a n d e d b e a c h e s a re c a l l e d r i d g e s ,

i s l a n d s o r c h e n i e r s d e p e n d i n g , i n p a r t , on t h e i r s i z e , and

r _______ Uk

” 1

F ig u r e 9a - View Look in g Shoreward from Tip o f O y s t e r R e e f o f f C h en ie r l a C r o i x .

W

F ig u r e - L o ok in g G ulfward a l o n g R e e f Shown i n F ig u r e 9 a . The Only L iv e O y s t e r s Found Here Today Are Rear t h e Gulfward Ext r e m i t i e s o f t h e R e e f .

45

p r i m a r i l y upon t h e whims o f l o c a l i n h a b i t a n t s . In V e r m i l i o n

P a r i s h t h e term r i d g e . when a p p l i e d to a s t r a n d e d b e a c h , i n

t i m a t e s a d e p o s i t o f v a r i a b l e l e n g t h , l e n s t h a n 250 f e e t

w i d e , and w i t h a maximum t h i c k n e s s o f f o u r f e e t . The term s

i s l a n d and c h e n i e r ( u s e d i n t e r c h a n g e a b l y i n t h i s p a r i s h )

im p ly a g r e a t e r w id t h und t h i c k n e s s , but t h e v a r i a b i l i t y i n

l e n g t h p e r s i s t s . T h i s c l a s s i f i c a t i o n d o e s n o t a p p l y in

Cameron P a r i s h ; w here " i s l a n d " u s u a l l y r e f e r s t o s m a l l

l i n e a r d e p o s i t s and t h e a p p e l l a t i o n " r id g e " i s g i v e n t o l a r

g e r , t h i c k e r d e p o s i t s . T h i s t e r m i n o l o g y , a l t h o u g h c o n f u s

i n g and a m b ig u o u s , i s w e l l e s t a b l i s h e d i n t h e v e r n a c u l a r and

w i d e l y u sed on p r e s e n t m aps . T h e r e f o r e , t h e w r i t e r b e l i e v e s

an i n f l e x i b l e d e f i n i t i o n o f r i d g e , i s l a n d , and c h e n i e r , a s

used i n s o u t h w e s t L o u i s i a n a , w ou ld o n l y l e a d to g r e a t e r con

f u s i o n and m i s u n d e r s t a n d i n g .

A good p o l i c y would be th e a p p l i c a t i o n o f c h e n i e r t o

a l l s t r a n d e d b e a c h e s , r e g a r d l e s s o f s i z e , and t h e e l i m i n a t i o n

o f t h e terras r i d g e and i s l a n d , now o f t e n a p p l i e d t o su ch d e

p o s i t s . T h i s w o u ld , h o w ev e r , e n t a i l c o n s i d e r a b l e a l t e r a t i o n

o f e x i s t i n g maps a n d , a l t h o u g h a w o r th y s u g g e s t i o n , c a n n o t be

p u r s u e d t o o p e d a n t i c a l l y . In t h i s r e p o r t c h e n i e r i s u sed t o

mean an o l d beach now s t r a n d e d i n t h e m arsh . The word was

a l s o used i n t h i s s e n s e b y Howe and R u s s e l l ( 1 9 3 5 ) . T h i s i s

n o t t h e a c c e p t e d d e f i n i t i o n t h r o u g h o u t c o a s t a l L o u i s i a n a .

R u s s e l l ( 1 9 3 9 , p* 4 5 ) h a s p o i n t e d o u t t h a t c h e n i e r s i s used

46

in t h e s o u t h e r n p a r t o f the M i s s i s s i p p i D e l ta t o mean any

h ig h ground and o r d i n a r i l y r e f e r s t o n a t u r a l l e v e e s o f aban

doned c h a n n e l s .

Note sh ou ld be ta k e n o f t h e f a c t t h a t C h en ier au T ig r e

and C hen ier La C r o i x , a s i n d i c a t e d on r e c e n t maps, are in

p a r t , b e a c h e s n o t e n t i r e l y surrounded by marsh. However, the

i n f l u x o f se d im e n t from th e A t c h a f a l a y a r e g i o n , g i v i n g r i s e

t o t h e r a p i d l y growing m u d f l a t s , i s s w i f t l y making t h e a p

p e l l a t i o n s v a l i d .

The c h e n i e r s d e r i v e t h e i r name from the heavy growth

o f o a k s w h ic h o f t e n cov er them. As French i s the la n g u a g e o f

th e l o c a l i n h a b i t a n t s , t h e a p p e l l a t i o n i s a n a t u r a l o n e .

Hackberry and c a c t u s a l s o f l o u r i s h on t h e b e a c h e s and chen-

i e r s o f t h e r e g i o n (T a b le I ) .

R e g i o n a l su b s id e n c e and compaction o f the u n d e r l y i n g

s e d im e n t s a f f e c t l a r g e b e a c h e s and c h e n i e r s to an even g r e a t

e r d e g r ee than n a t u r a l l e v e e s . T h is i s due t o th e g r e a t e r

w e i g h t o f the s a n d - s h e l l a c c u m u l a t io n s , and p r i m a r i l y to t h e

p r o p e r t i e s o f t h e t y p e o f d e p o s i t w h ich u s u a l l y u n d e r l i e s

them (See G e o l o g i c H i s t o r y S e c t i o n and F i g . 3 ) . P r o j e c t b o r

i n g s show s l i g h t com pact ion o f s e d i m e n t s be low c h e n i e r s and

b e a c h e s w i t h t h i c k n e s s e s o f fo u r f e e t . On l a r g e r d e p o s i t s ,

i t sh o u ld be n o t e d t h a t the g r e a t e s t downward b u lg e i s n o t

a lw a y s d i r e c t l y b e lo w th e beach or c h e n i e r c r e s t , but i s

o f t e n found seaward o f the c r e s t . Thus, s u g g e s t i n g t h a t a

p r e v i o u s beach c r e s t e d seaward from t h e p r e s e n t o n e , and t h a t

t h e o l d e r beach has been c o m p l e t e ly d e s t r o y e d by wave a c t i o n ,

i t s d e t r i t u s now c o m p r i s in g a l a r g e p o r t i o n o f th e new beach

formed a s h o r t d i s t a n c e i n l a n d . F i s k ( 1 9 4 8 , p . 2 3 ) makes n o t e

o f t h i s t y p e o f s i t u a t i o n a t H o l l y beach in Cameron P a r i s h and

a l s o p o i n t s o u t t h a t H o l l y Beach has s e t t l e d i n t o t h e l o o s e l y

c o n s o l i d a t e d G u lf bottom d e p o s i t s o f c l a y s and s i l t y c l a y s by

o v e r two f e e t . Compaction and s u b s i d e n c e , o f c o u r s e , a l l o w

th e marsh t o e n c r o a c h o v e r s t r a n d e d b e a c h e s ( c h e n i e r s ) , and,

i n t i m e , most s u r f i c i a l e v id e n c e o f t h e i r p r e s e n c e i s o b l i t e r

a t e d . The s u b s id e n c e i s much l e s s r a p i d where t h e beach has

been d e p o s i t e d d i r e c t l y upon a l e s s com p a ctab le fo r m a t io n or

has a s i m i l a r f i i m f o u n d a t i o n n e a r t h e s u r f a c e — here s lo w

r e g i o n a l s u b s id e n c e d o m in a te s .

On a e r i a l p h o to g r a p h s , s i l t b e a c h e s appear a s l i g h t ,

narrow, e v en t e x t u r e d , bands p a r a l l e l i n g t h e bay s h o r e s .

O f t e n , i f t h e p h otog ra p h s were taken a t low t i d e , a s i m i l a r

i r r e g u l a r zone i s found e x t e n d i n g a few hundred f e e t o f f

s h o r e . S a n d - s h e l l b e a c h e s s t a n d o u t a s w h i t e l i n e s a lo n g

t h e w a t e r ' s edge . V/ashover a r e a s p r e s e n t a more 01* l e s s even

t e x t u r e d , l i g h t c o l o r e d o r m o t t l e d app earance and c o n t a i n few

marsh l a k e s or ponds . T h is m o t t l e d e f f e c t i s e s p e c i a l l y n o t

i c e a b l e where th e v/ashover d e p o s i t s v a r y c o n s i d e r a b l y i n

t h i c k n e s s a l o n g t h e c o a s t , t h u s a l l o w i n g t h e u n d e r l y i n g ,

darker marsh to f i n d s l i g h t e x p r e s s i o n i n some p l a c e s .

C h e n ie r s are d i s c e r n a b l e a s l i g h t c o l o r e d , l i n e s and bands

( i n some c a s e s s e p a r a t e d by narrow b r e a k s ) a r c h i n g a c r o s s t h e

marsh. I f the c h e n i e r s or b e a c h e s are oak c o v ered t h e y e x

h i b i t a d a rk er s t i p p l e d t e x t u r e 021 a e r i a l p h o to grap h s ( F i g .

10).

M u d f l a t s , w h i l e n o t r e v e a l e d u n l e s s photographed a t

extrem e low t i d e , o f t e n cun be o u t l i n e d by th e narrow l i n e o f

b r e a k e r s which i s u s u a l l y n o t i c e a b l e a t t h e i r g u l fw a r d edge

( F i g . 1 0 ) . In any e v e n t , th e w ater c o v e r i n g t h e f l u i d c l a y

o f th e s h a l l o w m u d f la t i s much ca lm er and, t h e r e f o r e , p r e

s e n t s a d i f f e r e n t t e x t u r e on a e r i a l ph oto gra p h s 'than w a t e r s

gu lfw a r d o f t h e i r l i m i t s . Hearshore o y s t e r r e e f s s ta n d o u t

a s s h o r t b la c k l i n e s . At mean t i d e t h e r e e f s are o f t e n d e

l i n e a t e d by narrow z o n e s o f b r e a k e r s . Older r e e f s , f a r t h e r

o f f s h o r e , a r e commonly swept c l e a n o f s e d im e n t and are th u s

r e v e a l e d a s w h i te i r r e g u l a r l i n e s . P h o to grap h s ta k e n a t h i g h

t i d e u s u a l l y show l i t t l e o r 210 e v i d e n c e o f e i t h e r t h e n e a r

sh o r e or o f f s h o r e r e e f s .

B u r ied or p a r t i a l l y b u r ie d beach a c c u m u la t io n s o f sand

and s h e l l ( c h e n i e r s ) a r e , o f c o u r s e , e a s i l y r e c o g n i z e d in

bore h o l e s . They comprise th e c o a r s e s t d e p o s i t s e n c o u n te r e d

in m arshland work. E x tr em ely compact, reworked, b r o w n is h -

b l a c k , p e a t - l i k e m a t e r i a l i s o f t e n found i n t h in wedges or

p o c k e t s o v e r l y i n g th e b u r ie d gu l fw a r d s l o p e o f c h e n i e r s .

T h is t h i n l a y e r r e p r e s e n t s th e compacted r e s i d u e o f reworked

i

i 1 ^ V *MARSH

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49

F ig u re 10 - Chenier au T ig re Region

F ig u re 10 Chenier au T ig re Region

49

50

o r g a n ic rem ains ( " c o f fe e -g r o u n d " m a t e r i a l ) found a l o n g many

o f th e p r e s e n t b e a c h e s . M udfla t c l a y s , l e s s o r g a n i c and c on

t a i n i n g more s h e l l fragm ents than t y p i c a l marsh c l a y s , d i r e c t

l y o v e r l i e the g u l fw ard m arg ins o f s t r a n d e d b e a c h e s . F i s k

( 1 9 4 8 , p . 2 0 ) n o t e s the absence o f the clam R an g ia , u s u a l l y

found i n marsh and la k e bottom d e p o s i t s , from t h e s e m ud f la t

s e d i m e n t s . M udflat c l a y s a r e , in t u r n , o v e r l a i n by marsh de

p o s i t s , w h ic h a l s o o v e r l a p the landward edge o f t h e c h e n i e r

{ F i g . 3 ) .

R e l a t i v e l y t h i c k (o v e r f i v e f e e t ) sand and s h e l l de

p o s i t s are d i f f i c u l t t o p e n e t r a t e w i t h t h e hand auger due to

h o l e c a v i n g . However, i f the c h e n i e r o r beach can be p i e r c e d ,

a t h i n ( t h r e e t o s i x in c h ) l a y e r o f b l u e - g r e e n i s h , s l i g h t l y

o r g a n ic s i l t i s u s u a l l y e n c o u n te r e d d i r e c t l y ov er t h e marsh

d e p o s i t s . T h is narrow band i s undoubted ly th e r e s u l t o f

l e a c h i n g o f the o v e r l y i n g sand and s h e l l by downward p e r c o l

a t i n g w a t e r s . The p r e s e n c e o f green carbonate n o d u le s in

t h i s c o n t a c t zone between the c h e n i e r and u n d e r ly in g marsh

su p p o r t s t h i s c o n t e n t i o n . The p r e s e n c e o f i r o n , in the r e

duced s t a t e , e x p l a i n s the g r e e n c o l o r a t i o n o f t h e n o d u l e s .

Marshlands

Marshes make up the g r e a t e s t p o r t i o n o f th e r e g i o n ' s

land a r e a , f o r m in g , in some p l a c e s , a monotonous, c o a s t a l

band f i f t e e n m i l e s i n w id t h . The e l e v a t i o n o f t h i s f l a t ,

51

f e a t u r e l e s s expanse o f marshland seldom e x c e e d s two or t h r e e

f e e t (Mean G ulf L e v e l ) . A lthough t h e i r e x a c t b o u n d a r ie s a re

n o t o f t e n d e t e r m in a b le , t h e m arshlands are u s u a l l y d i v i d e d

i n t o r e g i o n s o f f r e s h , b r a c k i s h , and s a l t water m a rshes .

The g e n t l y d i p p i n g P r a i r i e T errace s u r f a c e gr a d e s Gulfward

i n t o a r e a s o f f r e s h w ater marsh, w h ich range from zero to f i v e

m i l e s in w i d t h . S a w g ra ss , s o f t r u s h , g i a n t b u l l r u s h , and p a i l l e

f i n e (T ab le I ) are th e dominant p l a n t s o f the f r e s h w a ter

m arsh. The t r a n s i t i o n zone between h ig h la n d and marsh o r i g i n

a l l y su p p orted e x t e n s i v e gro w ths o f c y p r e s s . R u t h l e s s lumber

in g o p e r a t i o n s , however, have lo n g s i n c e d e s t r o y e d t h e s e

m a g n i f i c e n t s t a n d s .

B r a c k is h w a t e r marsh, the most e x t e n s i v e t y p e , e x t e n d s

in l a n d from the bay and g u l f b e a c h e s f o r d i s t a n c e s o f f i v e t o

t e n m i l e s . Bayonet r u s h , r eed ca n e , c a t t a i l , o y s t e r g r a s s ,

and l e a f y t h r e e - s q u a r e g r a s s (T a b le I ) are t h e dominant p l a n t s .

As p r e v i o u s l y m entioned the aem arkat ion between the major marsh

t y p e s i s f l e x i b l e and not a lw a y s a p p a r e n t . T h is f a c t i s

e a s i l y unders tood when t h e extreme s a l i n i t y v a r i a t i o n s , t o which

most i n l a n d w a ter b o d i e s and t h e i r b o r d e r s are s u b j e c t e d , are

c o n s i d e r e d . During t im es o f storm l a r g e p o r t i o n s o f the

marshland may be in u n d a ted w i t h s a l i n e water from t h e G u l f ,

w h i l e d u r in g f l o o d p e r io d s much o f the marsh may be covered

11 O 'N e i l (1949) g i v e s a more d e t a i l e d breakdown and p r e s e n t s a map showing t h e v e g e t a t i o n a l t y p e s o f t h e L o u is ia n am a r s h e s .

52

w i t h r e l a t i v e l y f r e s h w a t e r . F i g u r e 11 shows t h e f l u c t u a

t i o n s in s a l i n i t y o v e r a t e n y e a r p e r i o d i n V e r m i l i o n Bay and

W hite L a k e . I t w i l l b e i n t e r e s t i n g t o n o t i c e t h e e f f e c t o f

t h e i n c r e a s i n g i n f l u x o f f r e 3h w a te r from t h e A t c h a f a l a y a

r e g i o n on t h e marsh v e g e t a t i o n o f t h i s r e g i o n d u r i n g t h e n e x t

f e w y e a r s .

I n a r e a s e f f e c t i v e l y d r a i n e d by many t i d a l b a yo u s and

a l o n g t h e G u l f s h o r e , s t a n d s o f b i a c k r u s h , s a l t marsh g r a s s ,

and n e e d l e c o rd g r a s s (T ab le I ) a r e f o u n d . These p l a n t s a r e

t y p i c a l o f t h e s a l t w a t e r marsh.

The n a t u r a l l e v e e s , P r a i r i e T e r r a c e r e m n a n t s , c h e n i e r s ,

b e a c h e s , an d s p o i l b a n k s ( d r e d g e d m a t e r i a l th row n a l o n g t h e

s i d e s o f a r t i f i c i a l l y c o n s t r u c t e d c a n a l s ) found t h r o u g h o u t the

m a r s h la n d s s u p p o r t v e g e t a t i o n o f a woody n a t u r e . D ep en d in g

p r i m a r i l y upon d r a i n a g e c o n d i t i o n s and e l e v a t i o n , t h e s e

f e a t u r e s a r e crowned w i t h g r o w t h s o f l i v e o a k , b l a c k w i l l o w ,

t o o t h a c h e t r e e , h a c k b e r r y , h a w th o r n , marsh e l d e r , g r o u n d s e l

t r e e , and s a l t m atr im ony v i n e ( T a b l e I ) .

T r a f f i c a b i l i t y c h a r a c t e r i s t i c s , a s p l a n t f o r m s , a r e

n o t t h e same f o r d i f f e r e n t t y p e s o f m arsh. A l th o u g h c o n f i n e d

to v e r y l i m i t e d p o r t i o n s o f t h i s r e g i o n (and t h e r e f o r e not

i n c l u d e d i n the above c l a s s i f i c a t i o n o f m a r s h la n d s ) t h e

f r e s h w a t e r f l o a t i n g marsh ( f l o t a n t ) i s the m ost d i f f i c u l t

t o t r a v e r s e . F l o t a n t ( R u s s e l l , 1942) c o n s i s t s o f a v e g e t a -

t i o n a l mat o v e r l y i n g a l i q u i d , o r g a n i c o o z e , v\hich o f f e r s

53

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1 9 3 0 1931 1 9 3 2 1 9 3 3 1 9 3 4 1 9 3 5 1 9 3 6 1 9 3 7 1 9 3 6 1 9 3 9 1 9 4 0

VERMILION BAY WHITE L A K E

GRAPH SHOWING FLUCTUATIONS IN SALINITY OVER A TEN YEAR PERIOD IN TYPICAL BRACKISH AND FRESH MARSH AREAS. (FROM O'NEIL 1949)

Figure 11

54

l i t t l e s u p p o r t i f t h e o v e r l y i n g mat i s b r o k e n . E x t e n s i v e

a r e a s o f f l o t a n t a r e f o u n d in the c o a s t a l p a r i s h e s t o t h e

e a s t . I t i s f o u n d i n t h i s r e g i o n n o r th o f V/ax l a k e i n a

d i s c o n t i n u o u s , s o u t h e a s t t r e n d i n g band a b o u t t h r e e m i l e s i n

w id th , w h ic h e x t e n d s f o r a p p r o x i m a t e l y t w e l v e m i l e s b e tw e e n

Bayou S a l e ' a n d the Lov;er A t c h a f a l a y a R i v e r ( F i g . 2 ) .

As R u s s e l l ( 1 9 4 2 , p . 79) h a s p o i n t e d o u t , s a l i n e

w a t e r s t e n d t o f l o c c u l a t e c o l l o i d a l m a t e r i a l s t h u s g i v i n g

r i s e t o r e l a t i v e l y f i r m c l a y s . M arsh es i n s a l i n e a r e a s a r e

t h e r e f o r e o r d i n a r i l y u n d e r l a i n by f i r m c l a y s and a r e more

e a s i l y t r a v e r s e d t h u n f r e s h w a t e r m ursh . However , l o c a l s e d i

m e n t a t i o n and s u b s u r f a c e c o n d i t i o n s i n some c a s e s c r e a t e e x

c e p t i o n s t o t h i s p r i n c i p l e . For e x a m p l e , a r e a s o f f r e s h

w a t e r marsh f o r m i n g a t h i n ( f i v e - s i x f e e t ) c o v e r i n g o v e r

t h e f i r m P r a i r i e T e r r a c e s u r f a c e a re more t r a l T i c a b l e th an

many r e g i o n s o f b r a c k i s h w a te r m arsh. I n c i p i e n t n a t u r a l

l e v e e s ( e . g . a l o n g t h e Lower A t c h a f a l a y a R i v e r ) r e p r e s e n t e d

by a two o r t h r e e i n c h l a y e r o f s i l t y c l a y , w h i l e not c a u s i n g

any g r e a t v e g e t a t i o n a l change , a s y e t , w i l l n e v e r t h e l e s s , i n

c r e a s e t r a f f i c a b i l i t y i n a narrow 2o n e c u t t i n g a c r o s s v a r i o u s

marsh t y p e s . The l a t t e r example i s , o f o o u r s e , a v e r y s h o r t

l i v e d s i t u a t i o n , a s f u r t h e r s e d i m e n t a t i o n w i l l c o m p l e t e l y

bury t h e e x i s t i n g f l o r a anu g i v e r i s e t o p l a n t s t y p i c a l o f

h i g h e r ground . T h e r e f o r e , a l t h o u g h s a l t and b r a c k i s h w a t e r

marsh i s u s u a l l y more t r a f f i c a b l e th a n f r e s h w a t e r m a rsh ,

l o c a l c o n d i t i o n s s h o u l d be c o n s i d e r e d .

On a e r i a l p h o t o g r a p h s m arshes a p p e a r a s e v e n t e x t u r e d ,

f e a t u r e l e s s , e x p a n s e s o f v a r i o u s s h a d e s ( F i g s , 6 and 7 ) .

T h is d i f f e r e n c e i n s h a d i n g , r a n g in g from l i g h t g r a y to b l a c k ,

i s d e p e n d e n t p r i m a r i l y upon v e g e t a t i o n a l d i f f e r e n c e s and s u r -

f i c i a l w a t e r c o v e r . D uring d r y p e r i o d s t h e upper p e a t y o r

o r g a n i c h o r i z o n i s o f t e n n a t u r a l l y i g n i t e d , r e s u l t i n g in e x

t e n s i v e marsh burns . These b u r n s a p p e a r as f a n sh a p e d ,

d a r k e r s p l o t c h e s on a e r i a l p h o t o g r a p h s . The a c u t e s p i c e s o f

t h e s e t r i a n g l e s , o f c o u r s e , p o i n t in th e d i r e c t i o n o f t h e

th en p r e v a i l i n g w ind . In a d d i t i o n , d u r i n g t h e l a t e summer

many marsh a r e a s a r e d e l i b e r a t e l y burned b y t r a p p e r s i n an

a t t e m p t t o i n s u r e a c o n s t a n t a n n u a l f o o d s u p p l y f o r t h e

m uskrat p o p u l a t i o n o f t h e i r t r a p p i n g l a n d s .

A l l marsh s e d i m e n t s a r e u s u a l l y v e r y s o f t a n d have

t h e h i g h e s t w a te r c o n t e n t o f any o f the v a r i o u s t y p e s o f

d e l t a i c d e p o s i t s . They a r e c h a r a c t e r i s t i c a l l y brown, b l u e -

g r a y , and g r a y - b l a c k . The c o l o r b e i n g d e t e r m i n e d , p r i m a r i

l y ! by t h e v a r y i n g c o n c e n t r a t i o n s o f o r g a n i c m a t e r i a l .

F r e s h w a t e r marsh s e d i m e n t s a r e u s u a l l y s o f t a n d c o n t a i n a

h i g h p e r c e n t a g e o f humus, r e s u l t i n g i n a d a r k c o l o r a t i o n ;

h o w ev e r , a l m o s t pure o r g a n i c m a t e r i a l when f i r m l y com pacted

( p e a t ) e x h i b i t s a b r o w n is h t i n t . B r a c k i s h and s a l t marsh

s e d i m e n t s a r e f i r m e r , l e s s o r g a n i c in c o m p o s i t i o n , c o n t a i n a

h i g h e r p e r c e n t a g e of c l a y o r s i l t y - c l a y , and are u s u a l l y

56

b l u e - g r a y i n c o l o r . The o r g a n ic m a t e r i a l p r e s e n t i n b r a c k i s h

and s a l t marsh s e d i m e n t s i s u s u a l l y d i s s e m i n a t e d t h r o u g h o u t

a s t i n y f l a k e s or p a r t i c l e s .

Lake s an d Bays

In a r e g i o n , su ch a s c e n t r a l c o a s t a l L o u i s i a n a , where

t h e normal w a t e r t a b l e i s u s u a l l y l e s s than two f e e t be low

marsh l e v e l , a n y s m a l l d e p r e s s i o n w i l l n a t u r a l l y form a l a k e

or pond. A l th o u g h th e o r i g i n a l o u t l i n e o f s u c h a d e p r e s s i o n

may be e l o n g a t e in an y d i r e c t i o n t h e o u t l i n e , a s t h e l a k e e n

l a r g e s , t e n d s t o become c i r c u l a r . Loca l i n h a b i t a n t s c l a i m

t h a t t h e s e round l a k s s o r i g i n a t e a s g e e s e o r muskrat " e a t

o u t s " or have t h e i r o r i g i n i n marsh f i r e 3 t h a t e f f e c t i v e l y

lo w e r t h e ground s u r f a c e by b u r n i n g , n o t o n l y the s u r f i c i a l

v e g e t a t i o n , but the upper, h i g h l y o r g a n i c , p o r t i o n o f t h e

marsh a s w e l l . R u s s e l l ( 1 9 3 6 , p . 117) p o i n t s o u t t h a t b o th

t h e o r i e s p r o b a b ly have some m e r i t , b u t s t a t e s t h a t u n c e r t a i n

d r a i n a g e a p p ea r s t o be a more common r e a so n f o r t h e i r form a

t i o n . He a l s o o b s e r v e s t h a t t h e v u l n e r a b l e s i t e s o f o r i g i n

a r e a r e a s where o r g a n i c m a t e r i a l c o n s t i t u t e a l a r g e p e r c e n

t a g e o f marsh f i l l .

Lakes e n l a r g e t t o o u g h wave e r o s i o n a l o n g t h e i r s h o r e s ;

t h e r e f o r e , i t would be l o g i c a l t o assum e t h a t a w a t e r body

would t e n d t o e l o n g a t e p a r a l l e l to the p r e v a i l i n g wind d i r e c

t i o n . T h i s a s s u m p t io n seems a t t r a c t i v e i n t h i s r e g i o n where

57

th e p r e v a i l i n g w i n d s a r e f r o m t h e s o u t h e a s t and th e maximum

v e l o c i t y w in d s u s u a l l y app roach from th e n o r t h w e s t . Thus

e l o n g a t i o n i n n o r t h w e s t - s o u t h e a s t d i r e c t i o n se em s m an d a to ry .

H ow ever , a s p r e v i o u s l y p o i n t e d o u t , e n l a r g i n g l a k e s t e n d t o

assum e a c i r c u l a r o u t l i n e . A p o s s i b l e e x p l a n a t i o n o f t h i s

s i t u a t i o n i s o f f e r e d by R u s s e l l ( 1 9 3 6 , p. 1 2 0 ) who s t a t e s

t h a t "more e r o s i o n o c c u r s i n t h e marsh d u r i n g one h u r r i c a n e

than d u r i n g s e v e r a l d e c a d e s o f o r d i n a r y w e a t h e r . V/hen a

h u r r i c a n e i s i n p r o g r e s s , a p o i n t i n t h e m a rsh es n o t o n l y

may e x p e r i e n c e i t s m ost v i o l e n t w in d s from a n y q u a r t e r b u t

a l s o w i l l , i n a l l p r o b a b i l i t y , f e e l heavy w in d s from a l l . "

The e n la r g e m e n t and c o a l e s c e n c e o f l a k e s w ith e a c h

o t h e r and o t h e r w a t e r b o d i e s i s e x t r e m e l y i m p o r t a n t i n t h e

f o r m a t i o n o f t h e l a r g e r b a y s . The s y n c h r o n o u s e n la r g e m e n t

o f L i t t l e W hite Lake and the arm o f V e r m i l i o n Bay i n t o w h ic h

V e r m i l i o n R i v e r e m p t i e s , g r a p h i c a l l y i l l u s t r a t e s t h e e f f e c t

o f c o a l e s c e n c e o f • round l a k e s w i t h o t h e r w ater b o d i e s , th u s

g i v i n g r i s e to c o n c a v e l y a r c u a t e s h o r e l i n e s . U. S . C. and

G. S . c h a r t number 200 (1 8 9 3 ) shows L i t t l e White Lake s e p a r

a t e d from V e r m i l io n Bay by a narrow s t r i p o f m arsh , w h ic h

today h a s been c o m p l e t e l y e r o d e d aw ay . I t i s i n t e r e s t i n g

to n o t e t h a t a p p a r e n t l y the l a k e h s e n l a r g e d m a in ly a t t h e

e x p e n s e o f i t s more e a s t e r l y m a rg in s .

'White Lake ( w e s t o f L i t t l e White Lake - F i g . 2) i s

shown a s two s e p a r a t e c i r c u l a r l a k e s on t h e G e n e r a l Land O f f i c e

58

Map o f L o u i s i a n a (New O r l e a n s , 1 838} c o m p i le d by C a te sb y

Graham. A l t h o u g h the map i s u n r e l i a b l e a s to d i s t a n c e and

o u t l i n e , th e e x i s t e n c e o f tvo l a k e s i n 1838 may be c a u t i o u s l y

a c c e p t e d . I f Graham’ s map i s a c c u r a t e White Lake i s one o f

t h e f i n e s t e x a m p le s o f ro u n d l a k e e n la r g e m e n t and c o a l e s c e n c e

t o b e found i n t h e L o u i s i a n a m a r s h l a n d s .

I t s h o u l d be b o r n e in mind t h a t , e v e n t u a l l y , a s e n

la r g e m e n t p r o g r e s s e s , p h y s i o g r a p h i c f e a t u r e s such a s l e v e e s ,

beach r i d g e s , a n d P r a i r i e T e r r a c e o u t c r o p s w i l l d e l i n e a t e

p o r t i o n s , i f n o t a l l , o f l a k e m a r g i n s . Thus , in some c a s e s ,

a l a k e may ( 1 ) o r i g i n a l l y e x h i b i t a n i r r e g u l a r o r a n g u l a r

o u t l i n e ( p o s s i b l y , in p a r t , a l r e a d y c o n t r o l l e d by p h y s i o

g r a p h i c f e a t u r e s ) ; ( 2 ) e v o l v e to a more r o u n d ed or c i r c u l a r

form; and ( 3 ) become m o d i f i e d , a s p h y s i o g r a p h i c f e a t u r e s a re

i n t e r s e c t e d by e n l a r g e m e n t and c o a l e s c e n c e , to fo rm a l a r g e r

body o f a n g u l a r 3 hape . The w r i t e r d o e s not c o n t e n d t h a t a l l

w a t e r b o d i e s fo r m i n t h i s s e q u e n c e ; h o w ev e r , e x a m p l e s o f a l l

t h e a b o v e m e n t io n e d s t a g e s o f d eve lop m en t can be f o u n d i n

t h e m a r s h l a n d s .

Many s m a l l i r r e g u l a r l y sh a p ed l a k e s , r e p r e s e n t i n g th e

i n i t i a l s t a g e , a r e f o u n d a l o n g t h e n o r t h e r n d io r e o f V e r m i l i o n

Bay so u th o f t h e I n t r a c o a s t a l Canal and s c a t t e r e d t h r o u g h o u t

t h e n o r t h w e s t e r n p o r t i o n o f Marsh I s l a n d ( F i g . 2 ) . O y s t e r

Lake, on Marsh I s l a n d , i s a g o o d exa m p le o f a more ad v a n ce d

s t a g e i n an a r e a where n o p h y s i o g r a p h i c f e a t u r e s a re p r e s e n t

c a p a b l e o f m o d i f y i n g t h e c i r c u l a r e n l a r g e m e n t . H o w ever , i n

t h e c o u r s e o f t i m e , t h e c o n c o m ita n t r e t r e a t o f t h e G u l f beach

and e n l a r g e m e n t o f O y s t e r Lake w i l l b r i n g the b e a c h i n t o c o n

t a c t w i t h the s o u t h e r n m argin o f the l a k e and m o d i f i c a t i o n o f

t h e c i r c u l a r out l i n e wi 1 1 , o f c o u r s e , r e s u l t . Bay Marchand

and Bay Champagne, n e a r the mouth o f Bayou L a fo u r c h e i n La

f o u r c h e P a r i s h , have a l r e a d y e x p e r i e n c e d t h i s t y p e o f t r u n c a

t i o n .

V e r m i l io n Bay may be c o n s i d e r e d an exam p le o f a s t i l l

more a d va n ce d s t a g e . O r i g i n a l l y th e a r e a p r e s e n t l y o c c u p i e d

by t h e bay c o n s i s t e d o f marsh d o t t e d v / i th s m a l l round lake-s

and s e v e r a l e l o n g a t e l a k e s , formed i n th e l e v e e f l a n k d e

p r e s s i o n s o f t h e m ajor s t r e a m f l o w i n g t h r o u g h the r e g i o n

( d e s o r i b e d in G e o l o g i c H i s t o i y s e c t i o n ) . R e g i o n a l a n d l o c a l

s u b s i d e n c e a i d e d in t h e f o i m a t i o n o f more and more p o n d s ,

w h ic h were r a p i d l y e n l a r g e d a t t h e e x p e n s e o f t h e e a s i l y

e r o d e d m a r s h . I n t i m e , more s u b s i d e n c e e n a b l e d arms and e x

t e n s i o n s t o t h e g u l f t o in v a d e t h e r e g i o n , even a c r o s s p h y s i o

g r a p h i c b a r r i e r s , and u n i t e w i t h t h e now e x t e n s i v e w a t e r

b o d i e s fo rm e d by t h e c o a l e s c e n e o f th e p r e v i o u s l y e x i s t i n g

l a k e s and p o n d s . M ouths o f s t r e a m s l e . g . , V e r m i l i o n R i v e r )

e n t e r i n g t h e bay became drowned, th u s f o r m i n g e x p a n d in g e s t u

a r i e s w h ic h e n g u l f e d more and more l a n d . The u n c o n s o l i d a t e d ,

w a t e r l a d e n , m arsh m a t e r i a l , o f c o u r s e , i s more e a s i l y e r o d e d

than f i r m l e v e e o r P r a i r i e T e r r a c e d e p o s i t s . T h e r e f o r e , when

a p h y s i o g r a p h i c b a r r i e r i s e n c o u n t e r e d by an e n l a r g i n g w a t e r

body e n l a r g e m e n t p r o c e e d s more r a p i d l y p a r a l l e l to t h e f e a

t u r e , t h u s r e s u l t i n g i n on e l o n g a t e o u t l i n e . V e r m i l io n Bay

t o d a y i s more or l e s s o u t l i n e d by s u c h b a r r i e r s ; h o w e v e r ,

t h e s e f e a t u r e s c a n n o t w i t h s t a n d the combined e f f e c t s o f s u b

s i d e n c e and wave e r o s i o n a n d a r e g r a d u a l l y b e i n g e r o d e d a w a y .

The n a t u r a l l e v e e s o f Bayou Cypremort, f o r ex a m p le , a t one

t ime u n d o u b t e d l y form ed t h e s o u t h e r n m a rg in o f t h e bay but

have s i n c e b e e n d e s t r o y e d by wave e r o s i o n o f t h e e n c r o a c h i n g

w a t e r s .

Thus i n a l l p r o b a b i l i t y the e x t e n s i v e , e n l a r g i n g w a te r

b o d i e s o f t o d a y were a t one t i m e , le ns t h a n 1000 y e a r s a g o ,

s m a l l , o v a l p o n d s o f s h a l l o w , p l a c i d w a t e r . I n d e e d , t h e r e

can be l i t t l e d o u b t t h a t such p r o c e s s e s have b e e n consum ated

and a r e o p e r a t i v e a t the p r e s e n t t i m e . (F or e x a m p l e , Sand

Lake, Lake Tom, and a f e w s m a l l e r l a k e s o f the N o r t h e a s t p o r

t i o n o f Marsh I s l a n d , w i l l , p r o b a b l y i n the n e x t t w e n t y

y e a r s , be i n c o r p o r a t e d i n t o Cote B la n c h e B a y . ) F u r th e r m o r e ,

s h i f t s i n a r e a s o f a c t i v e s e d i m e n t a t i o n can b r i n g a b o u t r e

f i l l i n g o f e x t e n s i v e w a t e r b o d i e s and c o n c e i v a b l y , w i t h su b

s i d e n c e and t i m e , p r o d u ce a s u r f a c e r e m i n i s c e n t o f c o n d i t i o n s

p r e v a i l i n g i n a r e g i o n h u n d red s or t h o u s a n d s o f y e a r s a g o .

In g e o l o g y n e v e r c e a s i n g change i s a dom inant c o n c e p t and

h e r e i n s o u t h e r n L o u i s i a n a t h e r a p i d i t y o f t h i s change i s n o t

e x c e e d e d anyw here on e a r t h . T h i s i s we11 e x e m p l i f i e d i n t h e

6 1

A t c h a f a l a y a B a s i n . The b a s i n , w h i c h was formed when t h e lo w

c e n t r a l p o r t i o n o f t h e Lower M i s s i s s i p p i A l l u v i a l V a l l e y b e

came c o m p l e t e l y su rro u n d ed b y n a t u r a l l e v e e r i d g e s b u i l t by

v a r i o u s M i s s i s s i p p i R i v e r c o u r s e s ( F i s k , 1 9 5 2 , p . 5 9 ) , c o n

t a i n s many e x t e n s i v e l a k e s ( e . g . , Grand L a k e , S i x - M i l e l a k e ,

Lake F a u s s e P o i n t e ) t h a t a r e r em n a n ts o f a much l a r g e r body

o f w a t e r . The a r e a has b e e n , and i s a t th e p r e s e n t t i m e ,

b e i n g f i l l e d in by s e d i m e n t b r o u g h t down b y t h e A t c h a f a l a y a

R i v e r . A t r a c t o f l a n d c o n t a i n i n g more t h e n f i f t y s q u a r e

m i l e s h a s been fo rm ed i n Grand Lake d u r i n g t h e p a s t t w e n t y -

t h r e e y e a r s .

As n o t e d a b o v e , an i n f l u x o f s e d i m e n t q u i c k l y a l l u v i -

a t e s e x t e n s i v e t r a c t s o f w a t e r . These e x t r a o r d i n a r y c h a n g e s

i n t h e l a n d - w a t e r b o u n d a r i e s a r e p o s s i b l e b e c a u s e o f t h e

s h a l l o w d e p t h s f o u n d i n most m arsh land l a k e s and b a y s .

D e p th s g r e a t e r t h a n t e n f e e t a r e v e i y s e ld o m r e c o r d e d e x c e p t

i n c h a n n e l s . P r i c e (1 9 4 7 ) h a s made some i n t e r e s t i n g o b s e r v a

t i o n s on t h e " a v e ra g e " w id th ( h a l f t h e sum o f t h e maximum

l e n g t h o f open w a t e r and t h e g r e a t e s t open w a t e r d i a m e t e r

r o u g h l y a t 9 0 L t o t h i s ) t o d e p t h r e l a t i o n s h i p s i n s e v e r a l o f

t h e l a r g e r w a t e r b o d i e s fo u n d in t h i s r e g i o n . He c o n c l u d e s

t h a t t h e r e i s a r o u g h , b u t d e f i n i t e and c o n s t a n t r a t i o o f

w id th to d e p t h c a p a b l e o f b e i n g p l o t t e d a s a s t r a i g h t l i n e

f u n c t i o n . The e q u a t i o n o f t h e l i n e w a s foun d t o be y = . 41x

+ 3 ( y = d e p t h i n f e e t ; x = " a v e rag e" w id th i n m i l e s ) . Howe v e r , s i n c e s o u n d i n g s f o r b a s i n s w i t h an " a v e rag e" w id t h o f

l e s s th a n 2 . 2 5 m i l e s w e r e l a c k i n g a t t h e t i m e , P r i c e s t a t e s

i t i s n o t known t h a t t h e s m a l l l a k e s and t i d a l b a s i n s f o l l o w

the d e v e l o p e d a v e r a g e l i n e . During t h e l a s t t h r e e y e a r s

many o f t h e s m a l l e r w a t e r b o d i e s o f t h e r e g i o n , a l l h a v i n g

"average" w i d t h s o f l e s s t h a n 1 . 5 m i l e s , have been sounded .

A p l o t o f s e v e n t e e n w i d t h - d e p t h r e l a t i o n s shows t h a t P r i c e ’ s

s t r a i g h t l i n e r e l a t i o n ( F i g . 12a ) d o e s n o t a p p l y t o t h e s e

s m a l l e r l a k e s (S ee F i g . 1 2 b ) . In a d d i t i o n , the w r i t e r b e

l i e v e s t h a t , a l t h o u g h p l o t t e d a s a l i n e by P r i c e t h e graph

sh o u ld show a f a i r l y w id e band f o r d e p t h v a l u e r e a d i n g s . In

o t h e r w ords an e r r o r o f one f o o t o r p o s s i b l y tw o , a s th e

’’a v e r a g e ” width i n c r e a s e s , i s t o be e x p e c t e d . The g r a p h s

make i t o b v i o u s t h a t major d i f f e r e n c e s i n the s i z e o f w a t e r

b o d i e s do n o t r e f l e c t s i m i l a r d i f f e r e n c e s i n d e p t h s .

M en tion s h o u ld b e made o f a s m a l l g r o u p o f l a k e s t h a t

do n o t f a l l i n t o a n y o f t h e p r e v i o u s l y d i s c u s s e d c a t e g o r i e s .

These a re t h e s a l t dome l a k e s . On e a c h o f t h e F iv e I s l a n d s

t h e r e a r e s m a l l t o p o g r a p h i c d e p r e s s i o n s t h a t have been

n a t u r a l l y f i l l e d by f r e s h w a t e r d r a i n a g e , fo rm in g s m a l l ,

a l o n g a t e l a k e s , po n d s or swamps. However, i n some c a s e s

underground s o l u t i o n o f s a l t h a s c a u s e d e x t e n s i v e c o l l a p s e

and r e l a t i v e l y l a r g e l a k e s have b e e n form ed ( e . g . , Lake

P e i g n e u r on J e f f e r s o n I s l a n d and B e l l e I s l e Lake in S t . Mary

P a r i s h ) .

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WATER BODIES PLOTTED

ATCHAFALAYA BAY BASTROP BAY LAKE BORCNE CALCASIEU LAKC WEST COTE BLANCHE BAY GALVESTON - TRINITY BAY LAKE MAUREPAS OYSTER BAY LAKE PONTCHARTRAIN SABINE LAKE LAKE SALVADOR TURTLE BAY VERMILION BAY WHITE LAKE

AVERAGE WIDTH IN MILES

FIGUREliG A. MODIFIED FROM PRICE 09 4 7 ). PLOT OF AVERAGE WIDTH TO MAXIMUM DEPTH FOR WATER BASINS OF A HUMID COAST. LINE! Y -0 .4 X + 3 .0 IS LEAST SQUARE AVERAGE FOR POINT DISPERSION. CROSS — BASIN NOT RECEIVING ALLUVIUM DIRECTLY; CIRCLE— BASIN RECEIVING ALLUVIUM DIRECTLY.

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LAKES PLOTTEDNAME MAXIMUM DIAMETERS AVERAGE WIDTH MAXIMUM DEPTH

(IN MILES) (IN MILES) (IN FEET)LITTLE WHITE LAKC 1.00 X 1 .00 I.OS 4 .0LAKC LUCIEN .4 3 X .6 3 1.03 3 .3LAKE LONG .17 X .76 .4 6 3 .0OYSTER LAKE 1.00 X I.OS 1.00 3 .0LAKE FERME 1.00 X .3 0 .73 3 .3LAKE A .4 0 X .3 0 .3 3 2 .0LAKE B .4 0 X .2 3 .3 3 2 .0LAKE SAND 1,16 X .6 2 1,00 3 .0LAKC C .S3 X .4 0 .4 6 I.SLAKE BLANC .3 3 X .3 0 .3 0 1.3LAKE TOM 1.10 X .6 0 .0 6 4 .0ONION LAKE .63 X .70 .7 6 2 .5LAKE TRIPOD .13 X .33 ,2 3 1.0BOB LAKE .2 3 X .23 .25 2 .0NORTH LAKE .3 0 X .3 6 .3 3 2 .0SOUTH LAKC .3 3 X .3 5 .4 3 2 .0FEARMAN LAKE 1.60 X .70 1.30 3 .6

+ t« ■3

AVERAGE WIDTH IN MILES

FIGURE32 B. PLOT OF AVERAGE WIDTH TO MAXIMUM DEPTH OF SEVENTEEN LAKES HAVING AVERAGE WIDTHS OF LESS THAN TWO MILES. NOTE THE DIVERGENCE FROM THE Y«0.4X + 3.0 LINE. POINTS 19, 25 , 29 FROM PRICE 0 9 4 7 ). CSEE FIGURE12 A.)

p h o t o g r a p h s ; h o w e v e r , t h e r e a r e many i n t e r e s t i n g d i f f e r e n c e s

i n s h a d e . For e x a m p le , th e i n t e r i o r l a k e s o f Marsh I s l a n d

u s u a l l y a r e o f a d a r k e r c o l o r a t i o n t h a n t h e l a k e s b o r d e r i n g

t h e b a y s , a n d th e b a y s t h e m s e l v e s . T h i s c o l o r d i f f e r e n c e i s

d u e , p r i m a r i l y , t o the amount o f su sp e n d e d m a t e r i a l i n th e

w a t e r . S u sp en ded p a r t i c l e s p r e s e n t many r e f l e c t i n g s u r f a c e s

to s u n l i g h t and c o r i s e q u e n t l y l a k e s o r bays c o n t a i n i n g much

su sp en d e d m a t e r i a l a p p e a r l i g h t e r on a e r i a l p h o t o g r a p h s t h a n

b o d i e s o f c l e a r w a t e r w h ic h l i g h t p e n e t r a t e s w i t h l i t t l e r e

f l e c t i o n . In a d d i t i o n , d e p e n d in g on t h e a n g l e w i t h which

s u n l i g h t s t r i k e s th e s u r f a c e o f t h e v / a t e r , t r o u b l e s o m e g l a r e

and r e f l e c t i o n may be e n c o u n t e r e d . Thus, e s t i m a t i o n o f

d e p t h o f w a t e r fro m a e r i a l p h o to g r a p h s i s n o t p r a c t i c a l

from the s t a n d p o i n t o f co l o r a t i on a lone .

Lake and bay b o t t o m d e p o s i t s c o n s i s t i n g o f b l u e - g r a y

c l a y s , s i l t y c l a y s ( F i g . 5 c ) and s i l t s w i t h s h e l l s a n d minor

l e n t i c u l a r b o d i e s o f s i l t y sa n d s a r e f o u n d th r o u g h o u t t h e

m a r s h l a n d s . The v /a ter c o n t e n t o f t h e s e d e p o s i t s i s o f t e n

q u i t e h i g h , b u t c o n s i d e r a b l y l e s s th an t h a t o f the f i n e r

and more o r g a n i c marsh d e p o s i t s . The p r e s e n c e o f s h e l l

f r a g m e n t s , m odera te amounts o f o r g a n i c m a t e r i a l , l a c k o f

o x i d a t i o n , and h i g i e r w a t e r c o n t e n t d i s t i n g u i s h l a k e and bay

b o t to m d e p o s i t s f r o m n a t u r a l l e v e e m a t e r i a l .

DRAINAGE CHARACTERISTICS

P r a i r i e T e r r a c e D r a in a g e

The u n d u l a t i n g , g e n t l y g u l f w a r d s l o p i n g , P r a i r i e T e r

r a c e s u r f a c e i s n o t c h a r a c t e r i z e d b y g o o d d r a i n a g e . R a in

w a t e r r a p i d l y c o l l e c t s i n t h e t o p o g r a p h i c l o w s f o r m e d , f o r

t h e m o s t p a r t , b y a b a n d o n e d P l e i s t o c e n e r i v e r c h a n n e l s and

the lo w a r e a s b e t w e e n t h e i r l e v e e r i d g e s . The i m p e r v i o u s

n a t u r e o f t h e s o i l a l s o l e a d s t o t h e f o r m a t i o n o f t h e many

po n d s and swampy a r e a s .

Most o f the p r e c i p i t a t e d w a t e r , h o w e v e r , d o e s n o t c o l

l e c t and s t a g n a t e i n t h e t o p o g r a p h i c l o w s . Some d r a i n s

d i r e c t l y i n t o t h e m a r s h , and t h e n c e t o o p en w a t e r . O th er

r u n - o f f f o l l o w s t h e o l d P l e i s t o c e n e c h a n n e l s ( e . g . , L i t t l e

Bayou i n V e r m i l i o n P a r i s h , F i g . 13) and r e a c h e s open w a t e r

v i a such s t r e a m s a s the V e r m i l i o n R i v e r , Bayou Queue de

T o r t e a n d t h e Mermentau R i v e r . Many o f t h e s e s n a i l n a t u r a l

d r a i n a g e c h a n n e l s , l o c a l l y c a l l e d " c o u l e e s , " a r e fo u n d

t h r o u g h o u t the r e g i o n .

I t i s o b v i o u s t h a t t h e d r a i n a g e o f t h i s o l d d e l t a i c

p l a i n ( P r a i r i e T e r r a c e ) i s i n f l u e n c e d to a g r e a t e x t e n t by

p r e v i o u s l y e x i s t i n g d r a i n s g e p a t t e r n s . R u s s e l l ( 1 9 3 9 ,

p . 1 2 2 7 ) h a s p o i n t e d o u t t h a t , "On lo w e r t e r r a c e s b r a n c h -

w orks a r e b e i n g e v o l v e d o u t o f o l d n e t w o r k s , t e r r a c e s c a r p

65

LITTLElAYOU

P l e is t o c e n e

MEANDERSCARS

PRAIRIE TERRACEVERMILIONRIVER

6 6

F i g u r e 13 - P r e s e n t D r a in a g e F o l l o w i n g P l e i s t o c e n e Meander S c a r s - S o u th o f A b b e v i l l e

F i g u r e 13 - P r e s e n t D r a in a g e F o l l o w i n g P l e i s t o c e n e Meander S c a r s - Sou th o f A b b e v i l l e

s t r e a m s , and m e a n d e r in g f l o o d - p l a i n c h a n n e l s . T h e i r d e v e l o p

ment i s d e t e r m i n e d by u p l i f t and r e g i o n a l t i l t i n g to w a r d the

a c t i v e d e l t a o f th e M i s s i s s i p p i R i v e r . " O r i g i n a l l y t h e n t h e

d r a i n a g e p a t t e r n o f t h e P r a i r i e T e r r a c e c l o s e l y r e s e m b l e d

t h a t o f t h e R e c e n t f l o o d p l a i n and c o a s t a l marsh a r e a s ; how

e v e r , s u b s e q u e n t u p l i f t ( d e s c r i b e d i n th e G e o l o g i c H i s t o r y

s e c t i o n ) h a s t e n d e d t o c r e a t e a more or l e s s t r e e - l i k e ( d e n

d r i t i c ) p a t t e r n , c h a r a c t e r i z e d b y u n i t i n g o f t r i b u t a r y

s t r e a m s t o fo rm one m ajor c h a n n e l . This p a t t e r n , h o w e v e r ,

h a s n o t r e a l i z e d c o m p le t e d o m in a n c e , and a b a s t a r d s y s t e m

o f t h e o r i g i n a l f l o o d p l a i n - c o a s t a l marsh p a t t e r n and th e

s u p e r im p o s e d s e m i - d e n d r i t i c com p lex i s c h a r a c t e r i s t i c o f t h e

P r a i r i e T e r r a c e s u r f a c e t o d a y .

M arsh land D r a in a g e

The c o m p lex , i n t e r s e c t i n g n e tw o r k o f s t r e a m s fo u n d i n

th e c o a s t a l marsh betv/een Bayou S a l e ’ and th e Lower A t c h a f a

l a y a R i v e r ( F i g . 2 ) i s l a c k i n g i n any d e f i n i t e t r e n d o r

a l i g n m e n t . The c o m p lex and u n p r e d i c t a b l e manner in w h ich

t h e s t r e a m s branch and r e u n i t e i s c h a r a c t e r i s t i c o f a m arsh

l a n d d r a i n a g e n e t w o r k . The h a p hazard d i r e c t i o n o f f l o w and

t h e p r e s e n c e o f in n u m e ra b le s m a l l , t o r t u o u s bay ou s a l s o

makes i t a p p a r e n t t h a t t h e r e a r e f e w i m p o r t a n t n e a r s u r f a c e

a l l u v i a l o r s t r u c t u r a l f e a t u r e s i n t h e Bayou S a l e ’ — Lower

A t c h a f a l a y a R i v e r a r e a , f o r th e p r e s e n c e o f t h e s e fo r m s would

6 8

be r e f l e c t e d In t h e d r a i n a g e p a t t e r n . A c a r e f u l s tu d y o f

the d r a i n a g e , however, d o e s r e v e a l a f e w such b u r ie d f e a t

u r e s . For e x a m p le , a s tu d y o f the d r a i n a g e p a t t e r n e x h i b i t

ed on a e r i a l p h o to g r a p h s r e v e a l e d a r e l a t i v e "high" e x t e n d

i n g from Possum P o i n t ( F i g . 2 ) t o t h e v i c i n i t y o f Clausen

( a l o n g a l i n e b e a r i n g a p p r o x i m a t e l y N65°W). B o r in g s made by

W i l l i a m M c l n t i r e s u p p o r t t h i s o b s e r v a t i o n , a s l e v e e m a t e r i a l

was e n c o u n t e r e d a t d e p t h s o f f i v e to se v e n f e e t i n t h e P o s

sum P o i n t r e g i o n ( p e r s o n n e l com m u n ic a t io n ) .

P h y s i o g r a p h i c f e a t u r e s such a s c h e n i e r s , b e a c h e s , and

n a t u r a l l e v e e s e x p o s e d a t th e s u r f a c e , o f c o u r s e , g r e a t l y

e f f e c t n a r s h la n d d r a i n a g e . The f e a t u r e s o f t e n o b s t r u c t

d r a i n a g e i n s u c h a manner t h a t an e l o n g a t e la k e o r s t r e a m

f l o w p a r a l l e l t o t h e o b s t r u c t i o n i s e s t a b l i s h e d . The mouth

o f t h e Mermeutau R iv e r , i n Cameron P a r i s h , has b e e n r e p e a t

e d l y f o r c e d westward by such e n c o u n t e r s w i t h c h e n i e r and

beach b r i d g e s . Southward f l o w i n g Y e l lo w Bayou ( F i g . 2) t u r n s

westward upon r e a c h i n g the n a t u r a l l e v e e s o f Bayou S a l e ’ and

p a r a l l e l s them t o i t s o u t l e t i n E a s t Cote B lanche Bay.

One m ig h t w e l l ponder why nea r s u r f a c e a l l u v i a l r i d g e s

a r e a p p a r e n t l y a b s e n t in the c o a s t a l r e g i o n be tw een V/ax Lake

and t h e Lower A t c h a f a l a y a R iv e r . Two p o s s i b i l i t i e s immedi

a t e l y p r e s e n t t h e m s e l v e s : ( l ) no l e v e e s y s t e m s have c r o s s e d

t h i s r e g i o n , and ( 2 ) t h e s y s t e m s are p r e s e n t but t o o d e e p l y

b u r ie d by marsh t o a l l o w r e f l e c t i o n on t h e s u r f a c e . The

secon d p o s s i b i l i t y i s u n d o u b ted ly c o r r e c t . However , f a r t h e r

w e s t l e v e e s o f t h e same a pp rox im ate a g e are s t i l l d i s c e r n i b l e

on a e r i a l p h o t o g r a p h s . The e x p l a n a t i o n o f t h i s c o n d i t i o n

p r o b a b ly l i e s i n the f a c t t h a t more s u b s i d e n c e h a s t a k e n

p l a c e in t h i s r e g i o n t h a n t o the w estw ard , for t h e a r e a o v e r

l i e s a d e e p t r o u g h c u t by t h e M i s s i s s i p p i R iv e r d u r i n g t h e

P l e i s t o c e n e , t h u s a l l o w i n g f o r more c o m p a c t io n o f u n c o n s o l i d

a t e d m a t e r i a l s o v e r l y i n g t h e P l e i s t o c e n e s u r f a c e . The

P l e i s t o c e n e p lu n g e s from a d e p t h o f f i f t y f e e t t o 180 f e e t

below the marsh s u r f a c e w i t h i n a d i s t a n c e o f f i v e m i l e s e a s t

ward from Possum P o i n t ( F i s k , 1952 , P l a t e 1 4 a ) .

V/est o f Wax Lake, where the P l e i s t o c e n e i s u s u a l l y

l e s s t i a n f i f t y f e e t below marsh l e v e l , n e a r s u r f a c e f e a t u r e s ,

su ch a s b u r i e d n a t u r a l l e v e e s and c h e n i e r s , a r e o f t e n r e

f l e c t e d in t h e to p o grap h y and d r a i n a g e . The p a r t i a l l y

b u r i e d , NW t r e n d i n g r i d g e s n ea r the e a s t e r n end o f C h en ier au

T ig r e s t a n d o u t a s a d e f i n i t e t o n a l t r e n d or g r a i n on a e r i a l

p h o to g ra p h s ( F i g . 1 0 ) . The a n c i e n t l e v e e s o f Bayou Cypremort

are e a s i l y d i s c e r n i b l e where t h e y i n t e r s e c t the s o u t h w e s t e r n

sh o r e o f V e r m i l io n Bay. In a d d i t i o n , the N-S t r e n d o f

bayous i n t h e n o r t h e r n p o r t i o n o f Marsh I s l a n d i s s u g g e s t i v e

o f near s u r f a c e c o n t r o l . I t s h o u ld be borne i n mind t h a t

o n l y i n a r e a s where the P l e i s t o c e n e l i e s a t a r e l a t i v e l y c o n

s t a n t depth and e x h i b i t s a un i form s l o p e i s the amount o f

l e v e e s u b s id e n c e a good c r i t e r i o n f o r d e t e r m i n a t i o n o f r e l a

t i v e a g e .

Depths o f M arshland Streams

T r e a d w e l l ( 1 9 5 5 ) , a f t e r p l o t t i n g the d e p t h s o f o v e r

n i n e t y s t r e a m s , h a s r e l a t e d s t r e a m w id t h to d e p t h i n th e S t .

Bernard P a r i s h m a r s h la n d s . Old abandoned d i s t r i b u t a r i e s and

open marsh bayous a r e t h e two major s t r e a m t y p e s r e c o g n i z e d

by T r e a d w e l l . T h is d i f f e r e n t i a t i o n i s v e r y im p o r ta n t a s d e

t e r i o r a t e d , more or l e s s s t r a i g h t , c h a n n e l s o f a n c i e n t d i s

t r i b u t a r i e s a r e u s u a l l y c o n s i d e r a b l y more s h o a l than w in d in g

marsh s t r e a m s o f com parable w i d t h s . T r e a d w e l l ' s sy s tem

makes i t p o s s i b l e , a f t e r d e t e r m i n i n g s t r e a m t y p e and w i d t h ,

t o e s t i m a t e th e d e p th o f a m arshland s t r e a m w i t h i n a few

f e e t . U n f o r t u n a t e l y , p r i m a r i l y due t o d i f f e r e n c e s i n d r a i n

age between t h e two a r e a s , the p r e s e n t w r i t e r has n o t

a c h i e v e d a n y c o m p a ra b le d e g r e e o f s u c c e s s w i t h w i d t h - d e p t h

p l o t s o f s t r e a m s in c e n t r a l c o a s t a l L o u i s i a n a . In the

c o a s t a l r e g i o n b e tw een Wax Lake and the Laver A t c h a f a l a y a

R iv e r many s trea m s o f e q u a l w i d t h , w i t h no v a l i d b a s i s f o r

d i f f e r e n t i a t i o n i n t o s e p a r a t e t y p e s , have d e p th d i f f e r e n c e s

a s g r e a t a s t e n f e e t i n the r e a c h e s ( s t r a i g h t p o r t i o n s o f

t h e s t r e a m ) . F a r t h e r w e s t i n t h e V e n u i l i o n and Cote B lanche

Bay a r e a t h e w i d t h - d e p t h r a t i o i s f a i r l y g o o d , but not v o r t h y

o f i m p l i c i t f a i t h . In t h i s w e s t e r n s e c t o r , e s p e c i a l l y on

Marsh I s l a n d , many c h a n n e l s a r e o b s t r u c t e d w i t h o y s t e r r e e f s ,

u s u a l l y l y i n g a f o o t or so be low w a t e r l e v e l but o f t e n e x

p o s e d a t l o w t i d e . Such o b s t r u c t i o n s , o f c o u r s e , c o m p l e t e l y

i n v a l i d a t e t h e e s t i m a t e s o f d e p th from t h e w i d t h - d e p t h p l o t .

P i g s , li+a, b , and c show s e v e r a l p r o f i l e s ta k en a l o n g O y s t e r

Bayou., Bayou J o e A c o u in and Bayou Chene, on Marsh I s l a n d , i n

an a t t e m p t to p r e s e n t a v e r y g e n e r a l i d e a o f w i d t h - d e p t h r e

l a t i o n s i n t h r e e f a i r l y r e p r e s e n t a t i v e m arsh land s t r e a m s . In

t h e s e f i g u r e s d e p t h s g i v e n a l o n g t h e b a y o u s a r e maximum

d e p t h s and o y s t e r r e e f s h a ve , for the m o s t p a r t , b e e n a v o i d

e d . Of c o u r s e , i t s h o u l d be r e a l i z e d t h a t r e e f s w i l l g i v e

r i s e t o many l o c a l d e p t h v a r i a t i o n s due n o t o n l y t o t h e i r

s h o a l i n g e f f e c t , b u t a l s o t o d i f f e r e n c e s in s c o u r and f i l l

a c t i o n c a u s e d b y t h e i r p r e s e n c e .

Many narrow s t r e a m s , w h ich d r a i n s m a l l m arsh land

l a k e s e x h i b i t w a t e r d e p t h s c o m p l e t e l y o u t o f p r o p o r t i o n t o

t h e i r w i d t h s . T h i s i s a r e s u l t o f the s c o u r which t a k e s

p l a c e a s a c o n s e q u e n c e o f t i d a l v a r i a t i o n s w h ic h c a u s e a l t e r

n a t e f i l l i n g a n d e m p ty in g o f t h e l a k e . Bayous d r a i n i n g

l a r g e r a n d / o r d e e p e r l a k e s , t h e r e f o r e , have d e e p e r c h a n n e l s .

Two i n t e r e s t i n g p r o f i l e s have b e e n r u n on a t i d a l c h a n n e l

d r a i n i n g a s m a l l Marsh I s l a n d Lake ( F i g . 1 4 d ) . One o f the

p r o f i l e s ( F i g . 14d, p r o f i l e l b ) was com p le te d ; a t f a i r l y h i g h

w a t e r when a v e r y s l i g h t outward f l o w w as i n p r o g r e s s . I t

i n d i c a t e d a maximum d e p th o f a p p r o x i m a t e l y f i v e and o n e - h a l f

f e e t . The o t h e r p r o f i l e ( F i g . 14d , p r o f i l e l a ) was tak en

i m m e d i a t e l y a f t e r a s e v e r e r a i n and w ind storm had i n u n d a t e d

th e marsh s u r f a c e t o a d e p t h o f one a n d a h a l f f e e t . There

L E F T ( W E S T ) BANK 0

WEST COTE b la n c h e bay

( O '©

1 2 ' \ \ ACOVJN

LOCATION OF PROFILESBAYOU BLANC QUADRANGLE

________ MARSH ISLAND

BAYOU JOE ACOUN PROFILES AUGUST 31, 1952

so_i_ 73

_1_173—I

L E F T (W E S T ) BANK23 SO 100

L E F T (W E S T ) BANK23 30 73

L E F T (E A S T )B A N K23 30 73

TILL

;S O r t f ] L L

L E F T (N O R TH ) BANK GULFOF

MEXICO

/ LOCATION OF PROFILES

BAYOU BLA N C QUADRANGLE M A RSH ISLAND

so

LEFT (E A S T ) BANK30 100 123

r > / / / ' ' ' ' ' S ' / / / / / / / / ,OYSTER BAYOU PROFILES

APRIL 2 8 ,’ 1952 10 20

L E F T (SO U T H ) BANK25 SO 73

40

HORIZONTAL AND VERTICAL SCALE (IN FEET)

Figure

14

LEFT (NW) BANK .12575 tooSO25

LOCATION OF PROFILESBAYOU LUCIEN QUADRANGLE

MARSH ISLANDLEFT (SW) BANK25

VERMIUONBAT

MUD FUATS ANO OYSTER

REEFS ARE EXPOSED AT

LOW TIDE

LEFT (W ) BANK25 SO

AVERACEDEPTH 4

BAYOU CHENE PROFILESMARCH 5 , 1952 .5 ' DEEP AT

BENOLEFT CSE) BANK2 5 SO

20 30

HORIZONTAL AND VERTICAL SCALE (IN FEET)

LOCATION OF PROFILES BAYOU BLANC QUADRANGLE

MARSH ISLAND

LAKE A

25 50

25 50

FIGURE ILLUSTRATING EROSION AND DEPOSITION IN TIDAL STREAMS. SEE TEXT P. 71

PROFILE la WAS SURVEYED IMMEDIATELY FOLLOWING A STORM THAT PUSHED GREAT QUANTITIES OF WATER OVER THE MARSH. THE EROSIVE POWER OF THIS WATER RETURNING TO THE GULF IS MADE APPARENT BY COMPARING THIS SECTION WITH PROFILE lb WHICH WAS SURVEYED ALONG THE SAME LINE, ON A CALM DAY, AT HIGH TIDE. PROFILE la WAS SURVEYED APRIL 12, 1952; PROFILE lb, SEPT. 3,1952.

(0

w a s , t h e r e f o r e , a s t r o n g c u r r e n t i n th e l i t t l e bay o u , chan

n e l i n g t h i s e x c e s s w u te r g u l l ’ward, and g i v i n g r i s e t o a

maximum d e p t h o f ten f e e t ; o n e a n d a h a l f f e e t o f w h ich can

be a c c o u n t e d f o r by t h e r i s e o f w a te r l e v e l . Thus t h e s m a l l

s t r e a m had s c o u r e d out i t s c h a n n e l by a p p r o x i m a t e l y t h r e e

f e e t i n a v e r y s h o r t t i m e . The i n c r e a s e i n d e p t h r e p r e s e n t s

t h e r e m o v a l o f a c r o s s s e c t i o n a l a r e a o f , a t th e v e r y minimum,

f i f t e e n s q u a r e f e e t . C o n s i d e r i n g t h a t t h e bayou i s a p p r o x i

m a t e l y 3 , 0 0 0 f e e t in l e n g t h and t h a t th e p r o f i l e s w e r e run

c l o s e to i t s o u t l e t , a r e a s o n a b l e v a l u e f o r t h e amount o f t h e

r e l a t i v e l y s o f t bottom s e d i m e n t removed w o u ld be 1 5 , 0 0 0 c u b i c

f e e t . The s t r e a m h a s s u b s e q u e n t l y r e f i l l e d i t s c h a n n e l to

the e x t e n t shown i n t h e p r o f i l e ( F i g . 14d , p r o f i l e l a ) ; how

e v e r , t h e e r o s i o n a l e f f e c t o f a s i n g l e s to r m on a m a rsh la n d

s t r e a m and the s u b s e q u e n t r a p i d i t y o f r e f i l l i n g i s w e l l

i l l u s t r a t e d .

The d e p t h o f the approach c h a n n e l , l e a d i n g t o a bayou

m outh, a c r o s s s h o a l bay b o r d e r s d e p e n d s , i n p a r t , upon the

d e p th o f the s t r ea m i t s e l f . However , th e a p p roa ch c h a n n e l

d e p t h r a r e l y e x c e e d s s i x f e e t , e v e n f o r t h e l a r g e s t t i d a l

s t r e a m s . F i n d i n g t h i s e l u s i v e , na rro w , u s u a l l y unmarked,

p a s s o f t e n p r e s e n t s somewhat o f a problem and i n a r e a s w here

o y s t e r r e e f s a r e p r e v a l e n t , p r e s e n t s a d e f i n i t e h a z a r d .

In summary, any a t t e m p t t o e s t i m a t e th e d e p t h o f a

m a rsh la n d s t r e a m s h o u l d t a k e i n t o c o n s i d e r a t i o n , a t th e v e r y

74

l e a s t , t h e f o l l o w i n g f a c t o r s : ( 1 ) w id th o f t h e s t r e a m ; ( 2 )

t y p e o f s t r e a m — abandoned d i s t r i b u t a r y , t i d a l , e t c . ; ( 3 ) th e

p r e s e n c e o r a b s e n c e o f o y s t e r r e e f s — i f d i s c e r n i b l e ; ( 4 ) a r e a

and d e p th o f l a k e , i f a n y , d r a i n e d ; ( 5 ) t im e o f t h e l a s t

storm ; and ( 6 ) s i z e of the t o t a l a r e a d r a i n e d . The l a s t

m e n t io n e d f a c t o r , i n many c a s e s , i s d i f f i c u l t t o a s c e r t a i n ,

f o r t h e t a n g l e d rrasses o f i n t e r c o n n e c t e d l a k e s and s t r e a m s

found i n some a r e a s makes t h e d e t e r m i n a t i o n o f major l i n e s o f

d r a i i a g e i m p r a c t i c a l .

E f f e c t s o f Man-Made S t r u c t u r e s on D ra inage

The e f f e c t o f a r t i f i c i a l c a n a l s a n d l e v e e s on marsh

land d r a i n a g e i s in many c a s e s t re m en d o u s . For e x a m p le , on

t h e U. S . C. and G. S. c h a r t n o . 200 ( 1 8 9 3 ) t h e w a t e r body

now c a l l e d Fearman Lake i s shown a s two l a k e s s e p a r a t e d by a

s t r i p o f marsh t h r e e q u a r t e r s o f a m i l e in w i d t h . The 1921

U. S , C. and G. S . c h a r t n o . 1277 i n d i c a t e d t h a t a narrow

c u t or p i r o g u e t r a i l had been made j o i n i n g t h e two l a k e s .

Today t h i s c u t , through n a t u r a l e n l a r g e m e n t , i s a b o u t 1600

f e e t wide and t h r e e and a ha I f f e e t d e e p .

Many o i l company c a n a l s , w i t h t h e i r f l a n k i n g s p o i l

ba n k s , c r o s s the marsh g i v i n g r i s e t o ch a n g e s o f d r a i n a g e

and h e n c e , v e g e t a t i o n . A lth o u gh t h e t r a p p e r s of t h e r e g i o n

a r e p r o b a b l y p io n e t o e x a g g e r a t e t h e e f f e c t s o f such c a n a l s

on th e v e g e t a t i o n o f t h e i r t r a p p i n g l a n d s , t h e r e c a n be no doubt t h a t c h a n g es do o c c u r a s a r e s u l t o f t h e i r c o n s t r u c t i o n .

75

In a d d i t i o n , a r t i f i c i a l l e v e e s dam many s tr e a m s and c a u s e

m o d i f i c a t i o n o f d r a i n a g e .

The c o n s t r u c t i o n o f d r a i n a g e c a n a l s , su c h a s t h e V/ax

Lake O u t l e t , has r e s u l t e d i n many a l t e r a t i o n s . The s p o i l

banks throw n up f l a n k i n g the c h a n n e l h a v e e f f e c t i v e l y d i v i d e d

the l a k e i n h a l f ; c a u s i n g a s h o a l i n g o f the two p o r t i o n s .

P r i c e ( 1 9 4 7 ) f o r m u l a t e s t h a t s e g m e n t a t i o n o f t i d a l b a s i n s

r e s u l t s i n an u p s e t o f t h e e q u i l i b r i u m c o n d i t i o n s and s h o a l

i n g t a k e s p l a c e a s a n a d j u s t m e n t to t h e n e w ly e s t a b l i s h e d

" a v erage" width . The e f f e c t s o f the Wax Lake O u t l e t a r e more

W id esp read t h a n t h i s , h o w ev e r . P r e v i o u s l y f i n e muds were

debouched a t t h e mouth o f t h e Lower A t c h a f a l a y a R i v e r , some

n i n e m i l e s t o t h e e a s t . The Wax Lake O u t l e t t h e r e f o r e , i n

e f f e c t , moved a p e r c e n t a g e o f t h i s s e d i m e n t s u p p l y f a r t h e r

w e s t , a n d t h i s , a l o n g w i t h t h e i n c r e a s i n g f l o w o f t h e A t c h a

f a l a y a R i v e r h a s r e s u l t e d in t h e r a p i d a c c u m u l a t i o n , d u r i n g

t h e p a s t ten y e a r s , o f t h e mud f l a t s now fo u n d a l o n g t h e G u l f

s h o r e o f V e i m i l i o n P a r i s h .

Thus , r e l a t i v e l y m inor m o d i f i c a t i o n s in m a rsh la n d

d r a i n a g e may c r e a t e many u n f o r e s e e n p r o b l e m s . I t i s t r u e

t h a t i n m ost c a s e s c a n a l s cut t h r o u g h th e marsh an d a c r o s s

l a k e s t e n d t o f i l l i n r a p i d l y , i n w h ic h i n s t a n c e , t h e prob lem

i s t o keep them open r a t h e r th a n c o n c e r n o v e r t h e i r c o n t r o l .

However , t h e p i * e - e x i s t i n g d r a i n a g e s h o u l d a l w a y s be c a r e f u l l y

c o n s i d e r e d b e f o r e a n y m o d i f i c a t i o n i s made, w h eth er in

a v o i d i n g h igh m a in t e n a n c e c o s t s or s i t u a t i o n s t h a t c o u l d d e s

t r o y l a r g e p o r t i o n s o f t h e marsh or a d v e r s e l y a f f e c t t h e

t r a p p i n g and s h e l l f i s h i n d u s t r i e s .

GEOLOGIC HISTORY OF THE ARM

Ago o f S e d im e n t s E x p o sed

The s t r a t a e x p o s e d a t th e s u r f a c e w i t h i n t h i s a r e a

a r e d e l t a i c p l a i n d e p o s i t s o f Recent and Late P l e i s t o c e n e*1 p

a g e . T h ese s e d i m e n t s w ere l a i d down w i t h i n t h e p a s t131 0 0 ,0 0 0 y e a r s o r so , and c o n s t i t u t e o n l y a t h i n upper

v e n e e r l y i n g upon many t h o u s a n d s o f f e e t o f o l d e r s t r a t a .

Near t h e Q u l f s h o r e t h e maximum t h i c k n e s s o f t h e P l e i s t o

cen e and R e c e n t d e p o s i t s i s a p p r o x i m a t e l y 3 >000 f e e t ( F i s k ,

1 9 4 4 , F i g . 7 0 ) .

F i s k ( 1 9 3 8 ) h a s e s t a b l i s h e d a f o u r - f o l d d i v i s i o n o f

P l e i s t o c e n e d e p o s i t s , t h e y o u n g e s t o r P r a i r i e f o r m a t i o n

b e i n g the o n l y one e x p o s e d a t t h e s u r f a c e in t h i s r e g i o n . ^

The d i v i s i o n i s b a s e d on t h e m o d i f i c a t i o n o f s e d i m e n t a t i o n

P o s s i b l y T e r t i a r y e x p o s u r e s a r e f o u n d on some o f t h e F i v e I s l a n d s .

F i s k ’ s ( 1 9 4 4 , 1 9 4 7 , 1952) d a t i n g f o r t h e P l e i s t o cen e and h i s f o r m a t i o n a l breakdown w i l l be f o l l o w e d i n t h i s r e p o r t . I t s h o u l d be b o r n e i n m in d , h o w e v e r , t h a t t h e a c t u a l d a t e s a r e s t i l l v e r y much i n q u e s t i o n . T row br idge ( 1 9 5 4 ) h a s r e c e n t l y made a f a i r l y e x h a u s t i v e s e a r c h o f t h e l i t e r a t u r e and p r e s e n t s a v e r a g e f i g u r e s , w h ich d i f f e r from t h o s e o f F i s k . For e x a m p l e , t h e b e g i n n i n g o f t h e R e c e n t a s g i v e n by Trowbridge i s a p p r o x i m a t e l y 1 5 , 0 0 0 y e a r s a g o , which i s 1 0 , 0 0 0 y e a r s l a t e r t h a n t h e 2 5 , 0 0 0 y e a r e s t i m a t e o f F i s k ;

^ Woodward a n d Gueno ( 1 9 4 1 ) have p r e s e n t e d a g e o - c h r o n i c synonymy o f P l e i s t o c e n e f o r n a t i o n s and t e r r a c e s o f th e G u l f and A t l a n t i c c o a s t a l p l a i n s t h a t i s e x t r e m e l y h e l p f u l when d o i n g P l e i s t o c e n e r e s e a r c h i n t h i s r e g i o n .

77

78

c a u sed by P l e i s t o c e n e o s c i l l a t i o n s in s e a l e v e l . These

o s c i l l a t i o n s w e r e , i n t u r n , th e r e s u l t o f p e r i o d i c accum ula

t i o n and outward spread o f g l a c i a l i c e from p o l a r c e n t e r s .

Such amassment o f i c e c a u s e d a d r o p o f s e v e r a l hundred f e e t

i n s e a l e v e l , t h e r e f o r e , due t o t h e l o w e r i n g o f b a s e l e v e l ,

th e g r a d i e n t , v e l o c i t y , t u r b i d i t y , and t r a n s p o r t i n g power o f

th e G ulf C o a s t s t r e a m s i n c r e a s e d . Thus t h e s t r e a m s became

e n tr e n c h e d and g r e a t q u a n t i t i e s o f c o a r s e sand and g r a v e l s

were c a r r i e d t o th e G u l f . L a t e r , a s th e i c e s h e e t s r e t r e a t

e d , r e t u r n i n g t h e m e l t w a t e r t o t h e ocean and c a u s i n g the s e a

l e v e l t o r i s e t o a b o u t i t s fo r m e r p o s i t i o n , the e n t r e n c h e d

v a l l e y s were a l l u v i a t e d , in an e f f o r t t o a d j u s t t o t h e new

base l e v e l , by the same s t r e a m s t h a t c u t them . The lower

p o r t i o n o f t h i s a l lu v i u m c o n s i s t s o f c o a r s e sa n d s and g r a v e l s ,

but a s the s e a ( b a s e - l e v e l ) c o n t in u e d to r i s e b o th the quan

t i t y and t h e g r a i n s i z e o f d e t r i t u s s u p p l i e d to t h e r i v e r s

was d im in i s h e d ; th e a l l u v i u m d e p o s i t e d i n the v a l l e y s became

p r o g r e s s i v e l y f i n e r g r a i n e d , and t h e r a t e o f v a l l e y a l l u v i a -

t i o n d e c r e a s e d . T h is f i n e r m a t e r i a l i s c a l l e d t o p - s t r a t u m

^ B a u l i g ( 1 9 3 5 ) p o s t u l a t e d t h a t t h e r e h a s b e e n a g e n e r a l l o w e r i n g o f s e a l e v e l s i n c e l a t e C e n oz o ic t im e s (n o t c o n n e c te d w i t h g l a c i a t i o n ) , and t h a t t h e P l e i s t o c e n e v a r i a t i o n s in s e a l e v e l w ere mere f l u c t u a t i o n s i n t h i s downward t r e n d , which was p o s s i b l y c a u s e d b y d e f o r m a t io n and d e e p e n i n g o f t h e ocean b a s i n s . B a u l i g ' s i d e a s do n o t a g r e e w i t h F i s k ' s h y p o t h e s i s t h a t a f t e r e a c h g l a c i a t i o n s e a l e v e l r e t u r n e d t o t h e same a p p r o x im a te p o s i t i o n .

79

and the v a l l e y - f i l l i n g p o r t i o n o f the P r a i r i e T e r r a c e , t h e r e

f o r e , c o n s i s t s o f a c o a r s e b a s a l s u b s t r a t u m o v e r l a i n by a

f i n e r g r a i n e d top-3tratum.

The P r a i r i e Form ation was l a i d down d u r i n g t h a t p o r

t i o n o f the P e o r ia n I n t e r g l a c i a l S ta g e ( F i g . 15a) when t h e

s e a l e v e l was r i s i n g ( e x t e n d i n g from a b o u t 1 1 0 ,0 0 0 t o 7 0 ,0 0 0

y e a r s a g o ) . A p p r o x im a te ly 7 0 , 0 0 0 y e a r s ago the p o l a r i c e

ca p s began to expand , l o w e r in g s e a l e v e l and f o r c i n g t h e

c o a s t a l p l a i n s tream s to c u t t r e n c h e s i n t h e new ly formed

P r a i r i e s u r f a c e . T h is v a l l e y c u t t i n g c o n t i n u e d u n t i l ap

p r o x i m a t e l y 2 5 , 000- 1 5 ,0 0 0 y e a r s a g o when the i c e a g a i n began

t o r e t r e a t ; a d d in g i t 3 m e l tw a te r t o the o c e a n s and r a i s i n g

se a l e v e l t o a b o u t i t s form er p o s i t i o n . I t i s p r o b a b le t h a t

th e major p o r t i o n o f t h i s r i s e o c c u r r e d b e tw een 2 5 ,0 0 0 and

8 , 0 0 0 y e a r s a g o , and t h a t a s l c w e r , more i n c o n s i s t e n t r i s e

has b e e n t a k i n g p l a c e s i n c e t h i s t im e. A r i s e o f s e a l e v e l ,

d u r in g the l a s t f i f t y t o 100 y e a r s , has b e e n n o te d by Marmer

(1949 and 1952) and Umbgrove (19 5 0 )* These and o t h e r o b s e r

v a t i o n s seem t o i n d i c a t e t h a t we a r e n o t y e t throug h t h e

G l a c i a l A g e s . T h is l a s t ( 2 5 , 0 0 0 - 1 5 , 0 0 0 y e a r s ago t o the

p r e s e n t ) r i s e i n s e a l e v e l , marked b y minor f l u c t u a t i o n s , has

r e s u l t e d in the f o r m a t i o n o f t h e Recent s u r f a c e , w h ic h com

p r i s e s the g r e a t e r p a r t o f the a r e a under d i s c u s s i o n .

A c o n c i s e summary o f the more im p o r ta n t e v e n t s and

p r o c e s s e s o f t h e Quaternary P e r i o d i s p r e s e n t e d by F i s k

80

( 1 9 5 2 , pp . 3 4 - 5 ) :

E v id e n c e i s a v a i l a b l e i n t h e a l l u v i a l d e p o s i t s o f t h e Lower M i s s i s s i p p i A l l u v i a l V a l l e y and a d j a c e n t a r e a s t h a t s e a l e v e l was lo w e r e d and l a t e r r e s t o r e d t o n e a r i t s p r e s e n t s t a n d f i v e s e p a r a t e t i m e s . Each o s c i l l a t i o n o f s e a l e v e l can be c o r r e l a t e d w i t h an advance and r e t r e a t o f t h e g l a c i a l i c e , and t h e i n t e r v e n i n g p e r i o d o f s t a t i o n a r y s e a l e v e l c a n be c o r r e l a t e d w i t h an i n t e r g l a c i a l s t a g e . The r e l a t i o n s h i p betw een c h r o n o l o g y d e v e l o p e d i n g l a c i a t e d p a r t s o f t h e c o n t i n e n t and Lower M i s s i s s i p p i V a l l e y s t r a t i g r a p h i c u n i t s i s shown by F ig u r e 8a . A t y p i c a l g l a c i a l c y c l e i s shown by F ig u r e 8b. / F i g u r e s 8 a and 8 b o f F i s k a r e r e p r o d u c e d i n th e w r i t e r ’ s F i g . 15a and b / 7

The r e g u l a r i t y o f th e c y c l i c a l p a t t e r n o f v a l l e y entr e n c h m e n t , v a l l e y f i l l i n g , and a l l u v i a l p l a i n d ev e lo p m en t i s c o m p l i c a t e d by t h e s t r u c t u r a l a c t i v i t y w h ich accompan i e d r i v e r mouth d e p o s i t i o n and a f f e c t e d t h e L o u i s i a n a c o a s t thro u gh o u t t h e Q u a tern ary p e r i o d . Each a l l u v i a l p l a i n was downwarped in i t s d e l t a i c p o r t i o n and contem p o r a n e o u s l y u p l i f t e d i n l a n d . The u p l i f t e d p o r t i o n became an a l l u v i a l t e r r a c e and fo rm ed the w a l l s o f the n e x t l a t e r e n t r e n c h e d v a l l e y s y s t e m . A d j a c e n t t o the p r e s e n t M i s s i s s i p p i V a l l e y a r e f o u r t e r r a c e s , r e p r e s e n t i n g f o u r form er f l o o d p l a i n s , e a c h w i t h i t s c h a r a c t e r i s t i c se q u e n c e o f a l l u v i a l d e p o s i t s . The o l d e s t f l o o d p l a i n form s t h e h i g h e s t t e r r a c e .

The d i f f e r e n t i a l movement, m en t io n ed by F i s k , and a

v e r y f l e x i b l e d i f f e r e n t i a t i o n between f l o o d p l a i n o r a l l u v i a l

p l a i n , w h ich ^ r a l l e l s t h e s t r e a m i n i t s v a l l e y , and th e

d e l t a i c o r c o a s t w i s e p l a i n , which p a r a l l e l s t h e c o a s t and i s

u s u a l l y more or l e s s p e r p e n d i c u l a r t o t h e g e n e r a l d i r e c t i o n

o f s t r e a m f l o w , i s v e r y i m p o r t a n t . Each t e r r a c e s u r f a c e

o r i g i n a l l y c o n s i s t e d o f t h e s e two a r e a l d i v i s i o n s . I t sh o u ld

be n o t e d a t t h i s t im e t h a t t h e b i - p a r t a t e d i v i s i o n o f t h e s e

d e p o s i t s , c o a r s e b a s a l and f i n e r upper p o r t i o n s , u s u a l l y

pronounced i n t h e f l o o d p l a i n f o r n a t i o n s i s n o t a s e a s i l y

n o t e d i n t h e c o a s t w i s e d e p o s i t s .

81

In t h i s a r e a t h e P l e i s t o c e n e e x p o s u r e s c o n s i s t o f th e

P r a i r i e d e l t a i c p l a i n , whose i r r e g u l a r s u r f a c e i s o v e r l a p p e d ,

a l o n g i t s b o r d e r s , by R ecent d e p o s i t s ( s e e F i g s . 3 and 4 ) .

On F i g . 15c n o t e t h e a p p r o x im a t e l o c a t i o n o f t h i s r e g i o n

sou thw ard o f the h in g e zone . T h is l o c a t i o n , on t h e down-

warped s i d e o f t h e f l e x u r e , makes i t p o s s i b l e f o r t h e R ecent

s e d i m e n t s to o v e r l a p t h e P r a i r i e d e l t a i c p l a i n . North o f

t h i s h i n g e zone t h e e q u i v a l e n t d e p o s i t s ( P r a i r i e a l l u v i a l

p l a i n ) , f l a n k i n g t h e M i s s i s s i p p i V a l l e y , r i s e ab o v e t h e

R e c e n t f l o o d p l a i n , f o r m i n g , i n p a r t , the v a l l e y w a l l s .

T h e r e f o r e , t h e R ecen t d e p o s i t s a r e in r e a l i t y an i n c i p i e n t

t e r r a c e f o r m a t i o n and s h o u l d th e i c e s h e e t s a d v a n c e and r e

t r e a t o n ce a g a i n t h e p r e s e n t d e l t a i c p l a i n w o u ld be down-

warped and b u r i e d ; w h e r e a s , t o t h e n o r th t h e p r e s e n t f l o o d -

p l a i n w o u ld be u p l i f t e d and d i s s e c t e d .

I f t h e R e c e n t d e p o s i t s a r e c o n s i d e r e d t o be an embry

o n i c t e r r a c e f o r m a t i o n , t h e r e i s l i t t l e b a s i s f o r t h e b r e a k

down o f t h e s e d e p o s i t s i n t o t h e tw o members p r o p o s e d by

J o n e s (1954» p . 8 8 ) . In e f f e c t , J o n e s h a s t r i e d to s e p a r a t e

th e f l o o d p l a i n d e p o s i t s f r o m t h e d e l t a i c o r c o a s t w i s e s e d i

m e n t s by d r a w in g an a r b i t r a r y l i n e , t h u s c r e a t i n g two e s s e n

t i a l l y e q u i v a l e n t members i n h i s so c a l l e d Le Moyen form a

t i o n , w h ich i n c l u d e s a l l t h e R e c e n t d e p o s i t s . T h i s l i n e ,

drawn s o u t h e a s t w a r d from F r a n k l i n , a c t u a l l y l i e s w i t h i n the

d e l t a i c p l a i n o f t h e M i s s i s s i p p i R i v e r as d e f i n e d by R u s s e l l

MAXIMUM

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I GOMERY I FORMATION I SURFACE 'FORMATION MODIFIED FROM FISK (1952) I SURFACE I . I __________

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Figure 15

RECENT DEPOSITS

mm PRAIRIE DEPOSITS

EARLIER PLEISTOCENE DEPOSITS MODIFIED FROM FISK (1952)

GENERALIZED STRUCTURAL RELATIONSHIPS OF THE MISSISSIPPI ALLUVIAL VALLEY (NOT DRAWN TO SCALE)

V . W W t u n c , u rCONTINENTAL SHELF

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CONSTRUCTED FROM WELL DATA PRESENTED IN FISK (1952)

WELL A - ATLANTIC NO. 1WELL B - KEMPER A -lWELL C - MARYLAND SITE 4WELL D - WAX LAKE SITE AWELL E - WAX LAKE SITE 1WELL F - POSSUM POINTWELL G - L.A. 1

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83

( 1 9 3 6 , p . k l )• J o n e s ' b a s i s f o r the breakdown l i e s i n t h e

f a c t t h a t one member o f h i s Le Ivloyen f o r m a t i o n ( Le Beau-

f l o o d p l a i n ) c o n t a i n s a 2a rge amount o f sand or sand and

g r a v e l i n t h e lov/er p a r t ( s u b s tr a tu m o f F i s k ) and the o t h e r

member ( M e r m e n t a u - c o a s t w i s e ) c o n s i s t s p r i m a r i l y o f s i l t y

c l a y o r c l a y . However, t h e c o a r s e m a t e r i a l l i e s in t h e

P l e i s t o c e n e t r o u g h o f t h e M i s s i s s i p p i R iv e r , t h u s t h e upper

p o r t i o n o f t h e Le Beau member i s p r e d o m in a n t ly o f t h e same

l i t h o l o g y a s th e e n t i r e Mermentau member. In F i g . l ^ d , a c

c o r d i n g t o J o n e s ' breakdown, the R e c e n t d e p o s i t s w e s t o f the

g e n e r a l l o c a l i t y o f Maryland S i t e ilk would be i n c l u d e d in

t h e Mermen t a u member o f t h e Le Mo yen f o r m a t io n ; w h e r e a s , the

R e ce n t d e p o s i t s t o t h e e a s t , form the Le Beau member. In

t h e w r i t e r ' s o p i n i o n , i t w ou ld be b e t t e r , but h a r d l y n e c e s

s a r y , t o g i v e th e o v e r l y i n g f i n e m a t e r i a l ( t o p - s t r a t u m and

c o a s t w i s e d e p o s i t s ) member rank a n d t o do l i k e w i s e w ith t h e

bands o f b a s a l c o a r s e m a t e r i a l ( s u b s t r a t u m ) .

The w r i t e r can s e e no o b j e c t i o n to g i v i n g t h e R ecen t

d e p o s i t s f o r m a t i o n r a n k , b u t he d o e s n o t f e e l t h a t f u r t h e r

breakdown i s n e c e s s a r y . In t h e p r e s e n t r e p o r t th e Recent

d e p o s i t s w i l l be c o n s i d e r e d a s a u n i t , i n c l u d i n g a l l t h e

c o m p le x ly i n t e r c a l a t e d marsh, m u d f l a t , b e a c h , l e v e e , back

swamp, e s t u a r i n e , and l a c u s t r i n e s e d i m e n t s t h a t a r e s e p a r a t e d

from th e u n d e r l y i n g P l e i s t o c e n e d e p o s i t s by a pronounced

e ro s i o n a l u n c o n f o r m i t y .

8 4

O r ig in o f th e P r a i r i e S u r f a c e

The P r a i r i e s u r f a c e i n S o u th w es t L o u i s ia n a i s c r o s s e d

by numerous s c a r s o f a n c i e n t s t r e a m c o u r s e s . S e v e r a l s o u t h

w e s t t r e n d i n g s c a r s , o f o l d Red R i v e r c h a n n e l s , c u t t h e n o r t h

w e s t corn er o f V e r m i l io n P a r i s h s o u t h o f Crowley . S i m i l a r

s c a r s are found t o t h e n o r t h w e s t i n A cadia and J e f f e r s o n

D a v is P a r i s h e s (l?i g . 1 6 ) , a l l m a i n t a i n i n g , more or l e s s , t h e

s o u t h w e s t t r e n d . A tw e n ty m i le wide b e l t , e x t e n d i n g s o u t h -

so u t h w e s t from L a f a y e t t e , e x h i b i t s w o n d e r f u l l y p r e s e r v e d ,

a l th o u g h somewhat subdued, meanders o f a l a t e P l e i s t o c e n e

r i v e r o f t h e s i z e o f t h e p r e s e n t M i s s i s s i p p i ( F i g . 1 6 ) .

South o f a l i n e j o i n i n g Kaplan and A b b e v i l l e t h i s zone ap

p a r e n t l y s p l i t s in t o two d i s t i n c t b e l t s ; o n e , t r e n d i n g south

from the v i c i n i t y o f K aplan , t u r n s westward upon a p p r o a c h in g

the p r e s e n t marsh c o n t a c t ; t h e o t h e r , c o n t i n u e s d i r e c t l y

south from A b b e v i l l e . The V e r m i l io n R iv e r o c c u p i e s t h e l a t

t e r s c a r th r o u g h o u t most o f i t s c o u r s e . Headward e r o s i o n by

e n t r e n c h e d P l e i s t o c e n e (L a te Y / i soon s in ) s t r e a m s and l a t e r a l

c u t t i n g by R e ce n t M i s s i s s i p p i R i v e r s has erod ed away p o r

t i o n s o f t h e I - r a i r i e s u r f a c e , form in g the n o r th w e s t t r e n d i n g

sc a r p a l o n g i t s e a s t e r n margin and d e s t r o y i n g most o f t h e

P l e i s t o c e n e meander b e l t north o f L a f a y e t t e .

The band o f r e l i c t P l e i s t o c e n e meanders l o c a l l y forms

th e h i g h e s t p o r t i o n s o f t h e t e r r a c e s u r f a c e and t h e land

s l o p e s g e n t l y away from t h e s e e l e v a t i o n s . Thus, t h e d r a in a g e

M ILES

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PLEISTOCENE MISSISSIPPI AND RED RIVER MEANDER SCARS IN SOUTH

CENTRAL LOUISIANAMODIFIED FROM J O N E S , T U R C A N , AND S K IB IT Z K E ( 1 9 5 4 )

A b a n d o n e d R e d R i v e r C h a n n e l s

A b a n d o n e d M i s s i s s i p p i R i v e r C h a n n e l s

C h e n i e r s

P r a i r i e T e r r a c e * ^

|______ | R e c e n t F l o o d P l a i n a n d M a r s h D e p o s i t s

A - G W e l l L o c a t i o n s f o r C r o s s S e c t i o nP r e s e n t e d o n F i g u r e i s d

7 N

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Figure 16

8 6

p a t t e r n i s p r i m a r i l y d e p e n d e n t upon th e r e l i c t c h a n n e l s and

a l l u v i a l f e a t u r e s o f t h e a n c i e n t s t r e a m . T h is zo n e i s a l s o

r e f l e c t e d i n t h e s u b s u r f a c e by t h i n n i n g o f t h e c l a y t o p s t r a -

tum o f t h e P r a i r i e f o r n n t i o n . A lo n g the meander b e l t of the

a n c e s t r a l M i s s i s s i p p i R iv e r th e c l a y i s u s u a l l y l e s s than

f i f t y f e e t t h i c k ( i n many c a s e s l e s s t h a n t w e n t y f e e t ) ,

w h e r e a s , on t h e w e s t e r n and e a s t e r n m a rg in s the c l a y i s much

t h i c k e r r e a c h i n g a t h i c k n e s s o f 100 f e e t w i t h i n f i v e or so

m i l e s o f t h e b e l t ( J o n e s , 1 9 5 4 , H a t e 4 ) . S i m i l a r d i s t r i b u

t i o n and t h i c k n e s s o f meander b e l t and f l o o d p l a i n d e p o s i t s

i s e x h i b i t e d in t h e v a l l e y o f th e modern M i s s i s s i p p i R i v e r .

F i s k (1 9 4 8 ) has p r e s e n t e d a s e r i e s o f d iagram s i l l u s

t r a t i n g t h e Late P l e i s t o c e n e h i s t o r y o f t h i s r e g i o n . The

f o l l o w i n g d i s c u s s i o n w i l l , i n p a r t , m e r e l y e l a b o r a t e on h i s

c o n c l u s i o n s , a s i l l u s t r a t e d in F i g . 1 7 . The i n t e r p r e t a t i o n s

drawn from , and t h e c a u s a l f o r c e s r e s u l t i n g i n , d e p o s i t i o n

and e n tre n c h m e n t do n o t , h o w ever , i n a l l c a s e s , a g r e e w i t h

t h o s e s u g g e s t e d by F i s k . Dr. F i s k s h o u ld n o t be h e l d r e

s p o n s i b l e f o r any s t a t e m e n t s n o t q u o te d or not d i r e c t l y con

cerned w i t h th e c h r o n o l o g i c a l s e q u e n c e a s p r e s e n t e d i n F i g . 17.

P r e v i o u s t o t h e t i m e i l l u s t r a t e d in F i g . 17a ( i . e . ,

d u r in g th e E a r ly W isc o n s in G l a c i a l S t a g e ) , s e a l e v e l was

low er by s e v e r a l hundred f e e t . S tream s had formed e n t r e n c h e d

v a l l e y s , i n a d j u s t m e n t to t h e lo w e r base l e v e l and i n c r e a s e d

LATE P L E IS T O C E N E GEOLOGIC HIMODIFIED FROM F

m m m m\ v-. ; :Vj:

x r

A EARLY SHORELINE OF PRAIRIE OELTAIC PLAIN B RED RIVER ALLUVIAL CONE ANDMEANDER BELT ON PRAIRIE SUI

icALCASIEU

D TERREBONNE DELTA AND MEANDER BELT OF THE MISS. R. E ENTRENCHMENT VALLEY SYSTEK/ DURING LATEST PRAIRIE TIME. GLACIAL STAGE.

LATE STAGES OF THE PLEISTOCENE (GLACIAL) EPOCf-

^ 1 5 0 , 0 0 0 Y R S . 1 2 5 ,0 0 0 Y R S. 1 0 0 ,0 0 0 Y R S . 7 5 ,0 0 0 Y R S . 5 0 , (

~ -----------------------S 2 2 i H 0 N _ 0 F srA © ""

EARLY WISCONSIN GLACIAL STAGEA C C U M U LA TIO N O F ICC U PO N C O N T IN E N T S W ITH S U B S E Q U E N T LO W ER IN G O F S E A L E V E L R E S U L T E D IN E N T R E N C H M E N T O F S T R E A M S AND V A LLEY C U T T IN G . EN TR EN C H M E N T V A L LE Y S D E V EL O PED D U RING T H IS S T A G E W ER E F IL L E D D U RIN G P E O R IA N IN T E R G L A C IA L S T A G E .

( 3 ) IN D IC A T E S C O R R E L A T IO N O F STA G E SH O W N BY DIAGRAM B.

PEORIAN INTERGLACIAL STAGE

M E L TIN G O F IC E S H E E T S FR O M C O N T IN E N T S C A U SE D A R IS E IN SE A L E V E L AND A L LU V IA T IO N O F V A LLEY S C U T DURING P R E V IO U S G L A C IA L S T A G E . 5 E 0 I - M E N T S LAID DOWN OURING T H IS ST A G E FO RM W H A T IS NOW C A LLED T H E " P R A IR IE F O R M A T IO N ."

LATE WISCONSA C C U M U LA TIO N O F A PPR O O F IC E U P O N C O N T IN E N T ! L O W ER ED 4 5 0 F E E T BEL< VALLEY S Y S T E M S C U T D F IL L E D D U R IN G T H E RECE

HISTORY O FIOM FISK (1948)

SOU TH L O U IS IA N A

C A P T UR IVER

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M: AND EARLY FORMED M ISS. R. IE SURFACE.

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SCONSIN GLACIAL STAGE ^A PPR O X IM A TE LY 2 0 MILLION C U . M l.

D N E N T S C A U S E D T H E S E A T O BE IT BELO W I T S P R E S E N T L E V E L .C U T DURING T H I S ST A G E W ERE E R E C E N T E P O C H . (S T A G E E )

RECENT EPOCHA S T H E ICE S H E E T S M ELTED FROM T H E C O N T IN E N T S , S E A L E V E L R O SE AND VALLEYS W ERE A LLU V IA TED . R E C EN T D E P O S IT S C O N S IS T OF A S E Q U EN C E O F B A S A L S A N D S AND G R A V E L S W ITH OVERLYING S A N D S , S IL T S , AND CLAYS,

PRAIRIE TERRACE SURFACE

OLDER DEPOSITS

RECENT MARSHLAND AND ALLUVIAL PLAIN

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88

d i s c h a r g e , " ^ which e x t e n d e d f a r beyond the p r e s e n t s h o r e l i n e .

G r a d u a l l y , how ever , a s t h e p o k r i c e m e l t e d ( P e o r i a n I n t e r -

g l a c i a l ) , s e a l e v e l c o n s e q u e n t l y r o s e and arms o f w a t e r

s l o w l y c r e p t i n t o the e n t r e n c h e d v a l l e y s y s t e m s . In a l l

c a s e s t h e m agnitude o f r i s e e x c e e d e d t h e d e p o s i t i o n a l a b i l i

t y o f t h e s t r e a m a n d , a l t h o u g h trem en dou s q u a n t i t i e s o f

se d im e n t were debou ch ed , t h e r e l e n t l e s s f i n g e r s o f w a t e r

probed f u r t h e r i n l a n d , t h u s b r i n g i n g e s t u a r i n e and m arine

d e p o s i t s , u n d e r l a i n by f l u v i a t i l e s u n d s , headward a l o n g the

v a l l e y f l o o r . T h e r e f o r e , a l o n g w i t h the s u r f i c l a l to n g u e o f

e n c r o a c h i n g 'water a s i m i l a r , s u b - s e a wedge o f c o a r s e a l l u

vium was e x t e n d i n g u p - v a l l e y .

F i n a l l y a p o i n t o f e q u i l i b r i u m w as r ea c h e d a n d , due

p r i m a r i l y t o d e c e l e r a t i o n o f s e a - l e v e l r i s e , t h e s h o r e l i n e

no l o n g e r r e t r e a t e d . About t h i s t im e t h e M i s s i s s i p p i and Red

R i v e r s began t o b u i l d t h e i r d e l t a i c p l a i n s se a w a rd , a s i l l u s

t r a t e d in F i g . 1 7a . Far tit; r upstream f l o o d p l a i ’ns c o n s i s t i n g

o f n a t u r a l l e v e e and back swamp d e p o s i t s w e re f o r m in g . T h us ,

i n the main t r o u g h s c o a r s e r a l l u v i u m v\us b l a n k e t e d by f i n e r

m a t e r i a l . As t h e d e l t a i c p l a i n a d v a n c e d seaward an d expanded

l a t e r a l l y , w i t h many s h i f t s i n r i v e r c o u r s e , t h e e s t u a r i n e

and m arine d e p o s i t s , o v e r l y i n g th e b a s a l f l u v i a t i l e sa n d s

•L® An i n c r e a s e i n d i s c h a r g e seem s p r o b a b le a s numero u s d a ta s u p p o r t t h e c o n t e n t i o n t h a t r a i n f a l l i n c r e a s e d g r e a t l y i n t h e i n l a n d r e g i o n s d u r in g g l a c i a l p e r i o d s .

89

( i n t h e trough ) a*id o l d e r P l e i s t o c e n e d e p o s i t s (on the

d i v i d e s ) , were o v e r la p p e d . F i g . 17b shov/s the a p p ro x im a te

maximum e x t e n s i o n s o f t h e M i s s i s s i p p i and Red R iv e r d e l t a s ,

p r e v i o u s t o t h e w estw ard s h i f t o f t h e M i s s i s s i p p i R iv e r and

i t s c a p t u r e of the Red R i v e r . The s h i f t occu rr ed r e l a t i v e l y

l a t e i n the P e o r ia n t ime and the Red R i v e r n e v er a g a i n f lo w ed

in d e p e n d e n t l y t o the g u l f d u r in g t h e P l e i s t o c e n e . The com

b in ed s tream s now b u i l t , what F i s k has ter m ed , the V e r m i l io n

D e l t a gu l fw ard from t h e v i c i n i t y o f White Lake ( F i g . 1 7 c ) .

A nother g r e a t change o c c u r r e d i n the c o n s t r u c t i o n o f

t h e P r a i r i e d e l t a i c p l a i n when the M i s s i s s i p p i R iv e r a g a i n

s h i f t e d i t s c o u r s e to t h e e a s t and c o n s t r u c t e d a d e l t a s e a

ward o f th e a r e a w h ich i s now Terrebonne P a r i s h ( F i g . 1 7 d ) .

As F i s k ( 1 9 4 8 , p. 28) s t a t e s :

There a r e two r e a s o n s f o r a ssu m in g t h a t t h i s s h i f t o c c u r r e d and f o r e s t a b l i s h i n g i t s p o s i t i o n . The V erm il - i o n - M i s s i s s i p p i meander b e l t i s cut i n t o on i t s e a s t e r n s i d e i n t h e M a r k s v i l l e K i l l s a r e a by a younger s e r i e s o f meander s c a r s o f P r a i r i e a g e . T h i s r e l a t i o n s h i p shows t h a t t h e M i s s i s s i p p i R iv e r l t d a younger c o u r s e th a n the V e r m i l io n and t h a t i t f lo w e d to the e a s t o f the V erm il io n meander b e l t . The s e c o n d r e a s o n for i n t e r p r e t i n g an e a s tw a r d s h i f t o f the M i s s i s s i p p i R iv e r i s t h a t th e m a ste r s t r e a m had to have such a p o s i t i o n e a s t o f the V e r m i l io n meander b e l t in o r d e r to become e n tre n c h e d where i t d id d u r in g t h e Late W isc on s in g l a c i a l s t a g e .

F i g . 17d shows t h e c o u r se of the M i s s i s s i p p i R iv e r immedi

a t e l y p r e c e d i n g the l o w e r in g o f s e a l e v e l accom panying the

Late W isc o n s in g l a c i a l s t a g e . With the l o w e r i n g o f s e a

l e v e l ( b a s e l e v e l ) and i n c r e a s e d d i s c h a r g e , entrenchm ent o f

t h e s tr ea m s i n t h e new ly formed P r a i r i e s u r f a c e t o o k p l a c e

90

( F i g . 1 7 e ) .

The u n v e i l i n g o f t h e R ecent Epoch in narked by the

b e g i n n in g o f a n o t h e r rhythm ic r i c e in s e a l e v e l . The

e n t r e n c h e d v a l l e y s , c u t in t h e P r a i r i e s u r f a c e , were th u s

c o n v e r t e d i n t o e s t u a r i e s and enbayments bottomed w i th

c o a r s e f l u v i a t i l e d e p o s i t s and o v e r l y i n g e s t u a r i n e and mar

i n e s e d i m e n t s . G r a d u a l ly , in a r e a s where d e p o s i t i o n cou ld

keep puce w i t h t h e d e c e l e r a t i n g r i s e in sea l e v e l , ^ d e l t a i c

f i l l i n g o f t h e s e enbayments began , and i s s t i l l in p r o g r e s s

a t t h e p r e s e n t t im e . I t s h o u ld be no ted t h a t th e s e d im e n ts

o v e r l y i n g t h e d i v i d e s between e n t r e n c h e d s tr e a m s would

r a r e l y e x h i b i t t h e same sequ en ce a s tho.se found i n the

t r o u g h s ( F i g . 1 8 a ) . T h e r e f o r e , t h e b a s a l su bstra tu m i s no t

n e c e s s a r i l y c o n t i n u o u s , c o a s t w i s e , in any o f the d e l t a i c

t e r r a c e f o r m a t i o n s o r , o b v i o u s l y , in t h e R ecent d e p o s i t s .

Thus s u b s u r f a c e c o r r e l a t i o n o f th e t e r r a c e s , on t h e b a s i s

o f f i n d i n g a c o a r s e b a s a l z o n e , i s v e r y hazardous i n some

a r e a s .

A com parison o f F i g s . 17d and 17f shows t h a t o f th e

o r i g i n a l l y d e p o s i t e d F r a i r i e d e l t a i c - and f l o o d - p l a i n l e s s

than o n e - h a l f o f i t s o r i g i n a l area i s exposed a t the s u r f a c e

t o d a y . Headward e r o s i o n o f t h e e n tr e n c h e d s t r e a m s formed

d u r in g th e Late W isc o n s in G l a c i a l S t a g e , l a t e r a l e r o s i o n by

The p r e s e n c e o r a b sen ce o f f l u c t u a t i o n s i n t h i s l a s t g r e a t r i s e o f s e a l e v e l i s s t i l l a d e b a t a b l e problem.

9 1

R e c e n t M i s s i s s i p p i R i v e r s , and t h e o v e r l a p p i n g o f R e c e n t d e

p o s i t s , c a u s e d by s u b s i d e n c e and r i s e o f s e a l e v e l , have

com bined t o o b l i t e r a t e and c o n c e a l many f e a t u r e s o f t h e o l d

s u r f a c e . However , many o b s e r v a t i o n s can be made from i t s

e x p o s e d p o r t i o n s a nd , b e i n g t h e y o u n g e s t and l e a s t d i s s e c t e d

o f t h e t e r r a c e s u r f a c e s , m ost o f t h e i n t e r p r e t a t i o n o f P l e i s

t o c e n e d e p o s i t i o n i s b a s e d upon s t u d y o f t h e P r a i r i e form a

t i o n . The mode o f o r i g i n i s made r e l a t i v e l y c l e a r by t h e

p r e s e n c e o f l a r g e , w e l l p r e s e r v e d m e a n d e r s . R i s k ( 1 9 4 8 , p .

28) a l s o o b s e r v e s :

A t t h e peak o f i t s d e v e l o p m e n t , t h e V e im i i l io n d e l t a o f t h e M i s s i s s i p p i R i v e r p r o b a b l y e x t e n d e d beyond t h e p r e s e n t s h o r e l i n e to t h e e d g e o f t h e c o n t i n e n t a l s h e l f / F i g . 17c 7 . T h i s o p i n i o n i s b a s e d on th e f a c t t h a t t h e o n l y t r a c e s o f t h e M i s s i s s i p p i R i v e r l e f t in V e r m i l i o n P a r i s h a r e t h o s e o f a w i d e l y m e a n d e r in g s t r e a m . S i m i l a r t r a c e s a l o n g t h e modern M i s s i s s i p p i R i v e r a r e n o t fo u n d c l o s e r t h a n 150 m i l e s a b o v e t h e Head o f P a s s e s . I t i s c o n c l u d e d t h e r e f o r e t h a t t h e mouth o f t h e P r a i r i e M i s s i s s i p p i R i v e r l a y a g r e a t d i s t a n c e s o u t h o f t h e V e r m i l i o n P a r i s h t r a c e s o f i t s c h a n n e l .

F i s k ( 1 9 4 4 , 1 9 4 8 , 1 9 5 2 ) h a s o u t l i n e d t h e P l e i s t o c e n e

h i s t o r y o f t h e M i s s i s s i p p i A l l u v i a l V a l l e y . H owever , a d e

t a i l e d r e v i e w o f P l e i s t o c e n e g e o l o g y i s beyond t h e s c o p e o f

t h i s r e p o r t ; th e main o b j e c t i v e b e i n g the i n t e r p r e t a t i o n o f

th e d e p o s i t s f l a n k i n g t h e P r a i r i e s u r f a c e — R e c e n t s e d i m e n t s .

O r i g i n o f t h e R e c e n t S u r f a c e

As p r e v i o u s l y s t a t e d , t h e R e c e n t s e d i m e n t s a r e s e p a

r a t e d from t h e u n d e r l y i n g P l e i s t o c e n e d e p o s i t s by a pronounced

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Figure 18

e r o s i o n a l u n co n fo rm ity and c o n s i s t o f c o m p le x ly i n t e r c a l a t e d

marsh, m u d f la t , b e a c h , l a c u s t r i n e , e s t u a r i n e , l e v e e , and

backswamp s e d im e n t s . In C e n t r a l C o a s t a l L o u is ia n a t h e Recent

f l o o d p l a i n i s r e s t r i c t e d to the n o r t h e a s t e r n p o r t i o n o f the

a r e a , w h i l e t y p i c a l d e l t a i c d e p o s i t s compose a Gulfward

t h i c k e n i n g wedge of c o m p le x ly i n t e r f i n g e r i n g R e ce n t s e d i

m ents s o u t h o f the e x p o s e d l;r a i r i e s u r f a c e . Each t y p e o f

d e p o s i t , w i t h i t s v e r t i c a l and l a t e r a l c h a n g e s , p r o v i d e s a

c lu e to t he i n t e r p r e t a t i o n o f t h e sed im e n ta ry h i s t o r y o f the

immediate a r e a and o f c o a s t a l L o u i s ia n a . The h i s t o r y o f

c o a s t a l L o u i s i a n a i s pro b a b ly more e a s i l y read i n t h i s r e g i o n

tl ian in any o t t e r s i m i l a r a r e a . Here some o f the o l d e r Re

c e n t M i s s i s s i p p i d e l t a s foun d t h e i r f i r s t e x p r e s s i o n a nd , a s

su b seq u e n t s h i f t s o f t h e a c t i v e d e l t a have been to t h e e a s t

ward, t h e i r t r a c e s have not been c o m p l e t e l y o b l i t e r a t e d .

The l a t e r d e l t a i c s h i f t s have been r e c o r d e d in t h e c h e n i e r

s y s t e m s , w h ich mark s h o r e l i n e f l u c t u a t i o n s in th e a r e a .

T h e r e f o r e , t h e f o l l o w i n g pages w i l l d e a l p r i m a r i l y

w ith th e major R e ce n t p h y s i o g r a p h ic f e a t u r e s o f th e a r e a i n

an attem pt to ( 1 ) d e s c r i b e t h e i r manner o f o r i g i n , (2 ) i n

t e r p r e t t h e i r s i g n i f i c a n c e i n the h i s t o r y of c o a s t a l L o u i s i

a n a , and p r i m a r i l y , (3 ) e s t a b l i s h t h e i r r e l a t i v e a g e s . The.

n a t u r a l l e v e e s o f Bayou S a l e ’ , Cypremort, Teche and V e r m i l io n

p l u s the c h e n i e r s , a n d b e a c h e s , c o n s t i t u t e th e major R e ce n t

94ISp h y s i o g r a p h ic f e a t u r e s o f i n t e r e s t . They w i l l be examined

i n s e q u e n c e .

The p r e - h i s t o r i c c u l t u r a l c h r o n o lo g y e s t a b l i s h e d by

P h i l l i p s , Ford and G r i f f e n . (1 9 5 1 ) has been used e x t e n s i v e l y

i n t h e f o l l o w i n g s e c t i o n a s an i n d i c a t o r o f r e l a t i v e a g e .

T h is c h r o n o lo g y i s based on changes in p o t t e r y ty p e and

o r n a m e n ta t io n t h a t accom panied deve lo p m en t o f I n d ia n c u l

t u r e s . P o t s h e r d s b e a r in g a p a r t i c u l a r d e s i g n or p a t t e r n are

th u s c o n s i d e r e d i n d i c a t i v e o f a c e r t a i n t im e p e r io d ( F i g .

1 8 b ) , The p r e s e n c e o f su ch a r t i f a c t s on th e l e v e e s o f an

abandoned s t r e a m th u s s u g g e s t s t h a t th e f l o w , d u r in g t h i s

c u l t u r e p e r i o d , was s u f f i c i e n t t o s u s t a i n an In d ia n s e t t l e

m ent . P o t s h e r d s and o t h e r a r t i f a c t s a re u s u a l l y c o n c e n t r a t e d

i n m id d en s , composed p r i m a r i l y o f Rangia s h e l l , which r e p r e

s e n t t h e r e f u s e heaps o f t h e I n d ia n s e t t l e m e n t s . F i s k ’ s

( 1 9 4 4 ) r i v e r c h r o n o l o g y , based on p h y s i o g r a p h ic and bore

h o l e e v i d e n c e , i s a l s o f r e q u e n t l y m en t io n e d . F a m i l i a r i t y

w it h t h e r e l a t i v e a g e s o f the d i v i s i o n s in b o th c l a s s i f i c a

t i o n s and t h e i r t im e e q u i v a l e n c y ( F i g . 18b) i s e s s e n t i a l f o r

t h e com prehens ion o f t h e m a t e r i a l t o be p r e s e n t e d .

18 The F iv e I s l a n d s , p a r t i a l l y o f R ecen t o r i g i n , w i l l n o t be d i s c u s s e d s e p a r a t e l y , however, m en t io n o f t h e i r o r i g i n and i t s e f f e c t on the o t h e r p h y s i o g r a p h ic f e a t u r e s w i l l be made.

Bayou S a le * System

A lth o u g h l o c a t e d in an im p o rta n t r e g i o n o f e a r l y

s e t t l e m e n t , Bayou S a l e ’ i t s e l f i s v e r y se ldom m ent ioned in

th e l i t e r a t u r e . S c a t t e r e d s t a t e m e n t s , how ever , i n d i c a t e

t h a t t h e r e was no through f l o w in th e bayou when w h i t e men

s e t t l e d in t h e a r e a .

G ath ca rt ( 1 8 1 9 , p . 98) r e f e r s t o th e bayou a s .

n o t h i n g more th a n a w in d in g g u l l y f i f t e e n f e e t w i d e , and

from tw e lv e t o e i g h t e e n i n c h e s d eep f i l l e d w i th Cypress

k n e e s . . ." Rend ( 1 9 2 7 , p . 182) s t a t e s :

Bayou S a l e ’ i n t h e p a r i s h o f S t . Mary t a k e s i t s name from t h e French p a r t i c i p i a l a d j e c t i v e s a l e ’ , ’’s a l t e d , " " s a l t . " That s a l e 1 i s t h e o r i g i n o f the name, and n o t th e French s a l e . " f o u l , " " d i r t y , " i sc l e a r l y proved by th e e a r l i e s t r e c o r d s .

In o t h e r words t h e bayou has been e s t u a r i n e and r e c e i v i n g

o n l y r a i n w ater f l o w s i n c e e a r l i e s t r e c o r d e d t i m e .

The f o r e s t s f l a n k i n g t h e bayou r e c e i v e d s l i g h t l y

more a t t e n t i o n . Levin ' J a i l e s , R e g i s t e r o f t h e Land O f f i c e

a t O p e lo u sa s i n 1 8 1 4 , in a l e t t e r t o C a t h c a r t ( 1 8 1 9 , p .

175) d e s c r i b e s t h e oak f o r e s t s a l o n g th e bayou and a l s o

s t a t e s , "There i s l i k e w i s e a to n g u e o f Wood la n d , p r ob a b ly

l i v e Oak, e x t e n d i n g about a m i l e and a h a l f a l o n g th e

C o a s t ." The rem nants o f t h e s e f o r e s t s can be seen today

n e a r th e mouth o f th e p r e s e n t bayou and a l o n g t h e c o a s t

where i t s l e v e e s f l a n k th e s h o r e l i n e ( F i g . 7 ) .

An a r t i c l e a p p e a r i n g in th e November 1 1 , 1847 i s s u e

96

o f t h e P l a n t e r ’ s Banner d e s c r i b e s th e bayou r e g i o n a s f o l

lows:

The Bayou S a l e ' o f i t s e l f p o s s e s s e s no rem arkable i n t e r e s t a s a w a t e r c o u r s e ; in d e e d i t i s n o t c o n s i d e r e d a n a v i g a b l e s trea m ; s m a l l b o a t s , how ever, may a scen d i t f o r some d i s t a n c e from i t s mouth; . . . The Bayou S a l e ’ t a k e s i t s r i s e n ea r t h e w e s t margin o f the T ech e , ab o u t se v en m i l e s be low F r a n k l i n , . . . and a f t e r p u r s u in g a w e s t e r l y c o u r se o f about 30 m i l e s through a r i d g e o f land o f unr i v a l l e d f e r t i l i t y , b o th p r u i r i e and w ood la n d , , i t e m p t i e s i n t o v/hat i s c a l l e d Bayou S a l e ' Bay ( E a s t Cote B lanche B a y ) , . . .

T h is s t r i p o f c o u n t r y , which some 30 y e a r s back was c o n s i d e r e d o f l i t t l e v a l u e , i s now a cha in o f sugar p l a n t a t i o n s f o r t h e whole e x t e n t , . . .

D e n n e t t ( 1 8 7 6 , p . 9 8 ) , I l i l g a r d ( 1 8 8 4 , p. 157) and

P e r r i n ( 1 8 9 1 , p. 8 ) a l s o m ention the f o r e s t s and 3ugar p l a n

t a t i o n s o f Bayou S a l e ’ , but g i v e v e r y l i t t l e i n the way o f

p h y s i o g r a p h ic d e s c r i p t i o n s .

Today the bayou i s e s t u a r i n e , owes any w a ter f l o w

( e x c e p t t i d a l ) to l o c a l r a i n f a l l , and, w i th t h e e x c e p t i o n o f

t h e extrem e d i s t a l p o r t i o n where i t has been dredged to a

d ep th o f a p p r o x im a t e ly n i n e f e e t , i s a l m o s t c o m p l e t e l y

f i l l e d w i t h v e g e t a t i o n .

The s tream h a s r e c e i v e d l i t t l e a t t e n t i o n i n more r e

c e n t p u b l i c a t i o n s . F i s k ( 1 9 4 4 , P l a t e 1 5 ) , f o r e x a m p le , does

n o t d e f i n i t e l y i n c l u d e Bayou S a l e ’ in any o f h i s d e l t a s y s

t em s . However, on one f i g u r e ( F i s k , 1952 , F i g . 14) th e

stream i s shown a s p a r t o f t h e M aringouin d e l t a s y s t e m .

T h is c o n n e c t i o n i s n o t m ent ioned i n the t e x t .

F i e l d v/orlc, combined w i t h a e r i a l p h o to g r a p h ic s t u d y ,

97

in th e Bayou S a l e 1 r e g i o n has r e v e a l e d s e v e r a l i n t e r e s t i n g

f a c t s .

( 1 ) The e x i s t i n g n a t u r a l l e v e e s f l a n k i n g Bayou S a l e '

a re s t e e p , narrow and o f a s i z e n o t comparable w i t h t h e

l e v e e s o f former M i s s i s s i p p i R i v e r s .

( 2 ) A c c r e t i o n s c a r s , n ea r th e p r e s e n t T e c h e - S a l e ’

j u n c t i o n , i n d i c a t e t h a t Bayou S a l e ’ f u n c t i o n e d a s a d i s

t r i b u t a r y o f t h e T e c h e - M i s s i s s i p p i , but a p p a r e n t l y became

s e a l e d o f f p r i o r t o Red R iv e r occupancy o f the T ech e .

( 3 ) Two broad , m a rsh -c o v er ed n a t u r a l l e v e e r i d g e s

d i v e r g e southward from t h e Bayou S a l e 1 tren d between B&you

Teche and th e I n t r a c o a s t a l C an a l .

( 4 ) A r t i f a c t s s u g g e s t i n g In d ia n o c c u p a t io n d u r in g

p r e - T c h e f u n c t e t ime have been found n o r t h e a s t o f B e l l e I s l e ,

a t Negro Hammock, and on Rabbit I s l a n d ( F i g . 2 ) .

( 3 ) V a r io u s e v i d e n c e i n d i c a t e s t h a t a c o n t i n u a t i o n o f

Bayou S a l e 1 e x i s t s t o the n o r th s i d e o f the Teche r i d g e .

The f a c t th&t the e x i s t i n g l e v e e s o f Bayou Sale* were

formed by a r e l a t i v e l y minor s tr ea m i s o b v io u s from t h e i r

narrow, s t e e p l y s l o p i n g p r o f i l e s arid t h e i r s i z e r e l a t i o n s h i p

t o t h e T e c h e - I u i s s i s s i p p i l e v e e s ( F i g . 1 9 ) . T h is s t e e p n e s s

i s t h e r e s u l t o f t h e a t t e m p t by a d i s t r i b u t a r y t o b u i l d i t s

l e v e e s to a h e i g h t comparable t o t h o s e o f t h e main s tr ea m .

As th e volume o f w a t e r , and hence t h e amount o f suspended

s e d im e n t , a v a i l a b l e t o t h e d i s t r i b u t a r y i s c o n s i d e r a b l y l e s s

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100

than t h a t o f th e main c o u r s e , narrow s t e e p l e v e e s are

f o r m e d . ^ Many exam ples o f t h i s s i t u a t i o n can be found in

the a c t i v e d e l t a o f t h e M i s s i s s i p p i R i v e r .

A l th o u g h p a r t i a l l y o b l i t e r a t e d by s u b s e q u e n t c u l t i v a

t i o n , an i n t e r e s t i n g p a t t e r n o f a c c r e t i o n s c a r s i s e x h i b i t e d

i n the S a l e ’ -T eche j u n c t i o n a r e a ( F i g . 2 1 ) . The s c a r s su g

g e s t t h a t Bayou S a l e 1 l e f t th e T e c h e - M i s s i s s i p p i R iv e r ap

p r o x i m a t e l y 1 . 3 m i l e 3 above i t s l a s t o c c u p ie d c h a n n e l . This

a c c r e t i o n p a t t e r n , showing downstream m i g r a t i o n o f a d i s

t r i b u t a r y c h a n n e l i s t y p i c a l o f s trea m a c t i o n . Y/elder (1 95 5 )

has p r e s e n t e d an e x c e l l e n t d i s c u s s i o n o f t h i s ty p e o f chan

n e l c l o s i n g and r e s u l t i n g a c c r e t i o n s c a r s .

Thus e v i d e n c e i n d i c a t e s t h a t t h e e x i s t i n g , c u l t i v a t e d

l e v e e s o f Bayou S a l e ’ were formed when t h e s tr ea m f u n c t i o n e d

a s a d i s t r i b u t a r y o f th e T e c h e - M i s s i s s i p p i R i v e r . However,

o l d e r , b r o a d e r , m a rsh -c o v er ed l e v e e r i d g e s are p r e s e n t in

th’e Bayou S a l e ' r e g i o n .

The d r a in a g e p a t t e r n , a s d e l i n e a t e d on a e r i a l p h o t o

g r a p h s , r e v e a l s a r e l a t i v e "high" e x t e n d i n g from C la u sen to

19 n a t u r a l l y , a s i s o b v io u s from F i g . 19, l e v e e s f l a n k i n g an abandoned c o u r s e w i l l v a r y c o n s i d e r a b l y i n s t e e p n e s s owing t o t h e i r p o s i t i o n a l o n g t h e s tr ea m ( c u t bank, r e a c h , e t c . ) , d i f f e r e n t i a l com pact ion o f u n d e r l y i n g s e d i m e n t , n e arb y t e c t o n i c u p l i f t ( e . g . , r e c u r r i n g upward movement o f s a l t do m es) , and o t h e r f a c t o r s . In s p i t e o f t h e s e s l o p e v a r i a t i o n s c e r t a i n d i f f e r e n c e s i n t h e l e v e e s o f v a r i o u s s trea m s a re e v i d e n t . N e v e r t h e l e s s , the w r i t e r d o e s n o t f e e l t h a t a q u a n t i t a t i v e approach to l e v e e com parison i s j u s t i f i e d .

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102

Possum Poj .nt ( P l a t e I , F i g . d ) , where a l a r g e p a r t l y b u r i e d

s h e l l m idden , o v e r l i e s o x i d i z e d l e v e e m a t e r i a l . The w id th o f

t h i s b u r i e d l e v e e r i d g e , a s r e f l e c t e d i n t h e d r a i n a g e p a t

t e r n , i s e q u a l t o t h e 0 , 6 m i l e a v e r a g e c u l t i v a t e d w id t h o f

t h e Bayou S a l e ' l e v e e s . A r t i f i c i a l l e v e e s have been c o n

s t r u c t e d s k i r t i n g t h e n a t u r a l l e v e e s o f Bayou S a l e ’ , t h u s

k e e p i n g t h e marsh w a t e r from t h e n a t u r a l l e v e e f l a n k s and

p r o v i d i n g more a r a b l e l a n d . T h e r e f o r e , t h e w id t h o f c u l t i

v a t e d land i s f a i r l y c l o s e t o th e a c t u a l w id th o f t h e Bayou

S a l e ' ( T e c h e - M i s s i s s i p p i d i s t r i b u t a r y ) l e v e e s . C o n s e q u e n t l y ,

a m a r s h - c o v e r e d l e v e e r i d g e s u r f i c i a l l y r e f l e c t i n g , i n s p i t e

o f s u b s i d e n c e , a w id t h com, a r a b l e t o t h a t o f t h e Bayou Gale*

l e v e e s w o u ld , i n r e a l i t y , be b r o a d e r than the S a l e 1 l e v e e s .

The l e v e e s o f t h e C la u s e n -P o s su m P o i n t t r e n d may, t h e r e f o r e ,

be c o n s i d e r e d t o be o f g r e a t e r p r o p o r t i o n s than t h o s e now

f l a n k i n g Bayou S a l e ' . There i s no i n c r e a s e i n w id t h o f t h e

p r e s e n t Bayou S a l e ’ l e v e e s n o r t h o f C l a u s e n , t h u s i n d i c a t i n g

t h a t t h e submerged l e v e e r i d g e was n o t formed a s a d i s t r i b u

t a r y o f t h i s s t r e a m . In a d d i t i o n , i t i s o b v i o u s t h a t l e v e e s

f l a n k i n g a d i s t r i b u t a r y would n o t be b r o a d e r th a n t h o s e

p a r a l l e l i n g t h e t r u n k s t r e a m , u n l e s s some s u b s e q u e n t s u r f i -

c i a l m o d i f i c a t i o n lias taken p l a c e . Thus th e C la u sen -P o ssu m

P o i n t r i d g e must have been formed p r e v i o u s t o t h e d e v e l o p

ment o f t h e Bayou G a l e ’ branch o f t h e T e c h e - M i s s i s s i p p i , and

i s - a p r i o r i - p r o b a b l y pre T e c h e - M i s s i s s i p p i i n a g e .

103

From Possum P o i n t southw ard t h e t r a c e s o f t h e t r e n d

a r e l e s s d i s t i n c t . H owever , V eatch ( I 8 9 9 ) h a s d e s c r i b e d

o b j e c t s , w h ich would now be i d e n t i f i e d a s a r t i f a c t s o f p r e -

T c h e f u n c t e a g e , from a s i t e l o c a t e d s l i g h t l y n o r t h e a s t o f

B e l l e I s l e , t h u s s u g g e s t i n g t h a t a s t r e a m w i t h h a b i t a b l e

l e v e e s was f l o w i n g i n t h e B e l l e I s l e a r e a d u r i n g p r e -

T c h e f u n c t e ( pre T e c h e - M i s s i s s i p p i - F i g . 18b) t i m e . On t h e

b a s i s o f t h i s c u l t u r a l e v i d e n c e t h e c o u r s e h a s been t e n t a

t i v e l y c o n t i n u e d t o A t c h a f a l a y a Bay ( P l a t e I , F i g . a - s trea m

c o u r s e 1 ) . .

A n o th e r r i d g e o f m a r s h - c o v e r e d l e v e e a p p a r e n t l y

d i v e r g e s from t h e p r e s e n t 3ayou S a l e ’ t r e n d n e a r H orth Bend

( P l a t e I , F i g s . a and d ) . I t s c o n t i n u a t i o n so u th o f t h e

I n t r a c o a s t a l C an a l has n o t been d e f i n i t e l y e s t a b l i s h e d ; how

e v e r , p r e - T c h e f u n c t e a r t i f a c t s have been r e p o r t e d from Negro

Hammock ( p e r s o n a l com m unicat ion - V/m. M c l n t i r e ) . U n f o r t u n

a t e l y s h o r e l i n e e r o s i o n has d e s t r o y e d t h e N egro Hammock s i t e

and i t s submerged r e m a in s a r e p r e s e n t l y l o c a t e d a l m o s t 300

y a r d s o f f s h o r e . However, t h e p r e s e n c e o f a r t i f a c t s washed

o n t o t h e a d j a c e n t b e a c h s u g g e s t s t h a t an a n c i e n t l e v e e -

f l a n k e d s t r e a m e x i s t e d in t h e r e g i o n a n d , c o n s e q u e n t l y , t h e

North Bend c o u r s e h a s b e e n t e n t a t i v e l y e x t e n d e d i n t o the

N egro Hammock a r e a .

The f a c t t h u t t h e broad l e v e e r i d e s d i v e r g e from t h e

Bayou S a l e ’ t r e n d s u g g e s t s t h a t t h e p r e s e n t , c u l t i v a t e d

104

Bayou S a l e 1 l e v e e s o v e r l i e o l d e r s i m i l a r d e p o s i t s . A p l a u s i

b l e r e l a t i o n s h i p b e tw e e n th e p r e s e n t , s t e e p , n e r r o w , l e v o e s

and t h e o l d e r u n d e r l y i n g d e p o s i t s i s p r e s e n t e d i n F i g . 2 2 .

The m ain Bayou S a l e 1 t r e n d i s u n d o u b t e d l y c o n t i n u o u s

t o B a b b i t I s l a n d ( P l a t e I , F i g s . a and d ) . B o r i n g s on

B a b b i t I s l a n d e n c o u n t e r e d l e v e e m a t e r i a l a t d e p t h s v a r y i n g

from two t o s i x f e e t and i n d i c a t e t h a t the l e v e e c r e s t s a r e

l o c a t e d t o t h e n o r t h o f t h e i s l a n d . S e v e r a l I n d i a n p r o

j e c t i l e p o i n t s , s u g g e s t i v e o f p r e - T c h e f u n c t e ( p r e - T e c h e -

H i s s i s s i p p i - F i g . lCb) a g e , have been fo u n d a l o n g t h e s h e l l

beuch w h ic h f l a n k s th e n o r t h e r n s h o r e o f th e i s l a n d . The

p r o j e c t i l e p o i n t s w e re p r o b a b l y d e r i v e d from m id d en s l o c a t e d

n e a r t h e c r e s t o f t h e o r i g i n a l Bayou B a l e 1 l e v e e s ( F i g . 2 2 ) .

The s u b s i d e d l e v o e s on w h ic h t h e m id d en s w ere l o c a t e d were

p r o b a b l y p a r t i a l l y c o v e r e d by t h e s t e e p , narrow l e v e e d e

p o s i t s o f t h e Buyou S a l e 1 d i s t r i b u t a r y o f th e T e c h e -

i u i s s i s s i p p i , and s u b s e q u e n t l y e x p o s e d t o wave a t t a c k .

Thus i t i s p o s s i b l e t h a t t h r e e p r e - T e c h e - L ' i s s i s s i p p i

c o u r s e s e x i s t i n t h e Bayou S a l e 1 r e g i o n . The s i z e o f t h e i r

m a r s h - c o v e r e d l e v o e s i n d i c a t e s t h a t th e s t r e a m s were more

i m p o r t a n t than t h e Bayou S a l e 1 d i s t r i b u t a r y o f t h e T e c h o -

I d i s s i s s i p p i . Such s t r e a m s c e r t a i n l y w ou ld have form ed

f a i r l y e x t e n s i v e d e l t a s i n a r e a s now c o v e r e d by t h e G u l f o f

I . i e x ic o . S h o a l a r e a s fo u n d o f f t h e p r e s e n t s h o r e l i n e ( P l a t e

I , F i g . d) p o s s i b l y r e p r e s e n t t h e u e l t a i c rem n a n ts o f t h e

105

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Figure 22

106

o r i g i n a l Bayou S a l e ’ s y s t e m (Morgan, Van L o p ik , and N i c h o l s ,

1953* PP* 6 - 8 ) . The g e n e r a l o u t l i n e o f t h e s e s h o a l s and t h e

f a c t t h a t t h e y a r e composed o f c o a r s e r m a t e r i a l t h a n t h e

s u r r o u n d i n g b o t t o m s ( C a r s e y , 1 9 5 0 , F i g . 1 5 ) c e r t a i n l y s u g

g e s t s a d e l t a i c o r i g i n . F u r t h e r m o r e , P r i c e ( 1 9 5 4 , F i g . 1)

h a s mapped t h i s p o r t i o n o f t h e g u l f a s a r e g i o n o f "Sub

merged D e l t a s . " Thus t h e i d e n t i f i c a t i o n o f the s h o a l a r e a s

a s subm erged d e l t a m a s s e s se em s v a l i d .

There i s , a t the p r e s e n t t i m e , no d i r e c t c o n n e c t i o n

b e tw e e n t h e l e v e e d e p o s i t s o f t h e m a in la n d and th e o f f s h o r e

d e l t a i c c o m p le x , h o w e v e r , o l d maps and c h a r t s i n d i c a t e t h a t

t h e p r e s e n t Bayou S a l e 1 t r e n d p r e v i o u s l y e x t e n d e d a s f a r

w estw ard a s Marsh I s l a n d and s u g g e s t a c o n n e c t i o n w i t h t h e

S h e l l Keys a r e a ( P l a t e I , F i g s . a and d) t o t h e s o u t h . For

e x a m p l e , t h e A d m i r a l t y C h a rt o f th e C o a s t o f ’. / e s t F l o r i d a ,20and t h e C o a s t o f L o u i s i a n a , w s u r v e y e d by G eorge Gauld in

th e y e a r s 1 7 6 4 - 1 7 7 1 * shows an a l m o s t c o n t i n u o u s s t r i n g o f

i s l a n d e x t e n d i n g from t h e Bayou S u l e ’ r e g i o n t o the S o u t h

e a s t e r n t i p o f Marsh I s l a n d . P l a t e I ( F i g . a ) p r e s e n t s a

t e n t a t i v e c o r r e l a t i o n o f t h e Bayou S a l e ' c o u r s e s and t h e o f f

s h o r e d e l t a i c m a s s e s .

I f t h e c o n n e c t i o n b e tw een t h e o r i g i n a l Bayou S a l e '

s y s t e m and t h e o f f s h o r e d e l t a i c m a s s e s i s a c c e p t e d , t h e

20 T h i s c h a r t i s r e m a r k a b ly a c c u r a t e and much b e t t e r th a n m o st c o a s t a l maps p u b l i s h e d a s l a t e a s 1 8 5 0 .

107

p r e - T e c h e - M i s s i s s i p p i a g e d e t e r m i n a t i o n o f t h e sy s te m i s

s t r e n g t h e n e d , f o r i t i s im p r o b a b le t h a t a mere d i s t r i b u t a r y

o f t h e T e c h e - M i s s i s s i p p i c o u l d have spawned t h e d e l t a i c

a r e a s s t i l l d i s c e r n i b l e o f f th e j j r e s e n t s h o r e l i n e . A c c e p t

a n ce o f t h e p r e - T e c h e - M i s s i s s i p p i a g e , h o w ev e r , demands th e

p r e s e n c e o f an e x t e n s i o n o f t h e Bayou S a l e 1 s y s t e m t o t h e

n o r t h o f t h e Teche r i d g e .

The Teche r i d g e fo rm s t h e s o u t h e r n and w e s t e r n bound

a r y o f t h e g r e a t A t o h a f a l a y a B a s i n . T h i s b a s i n , w h ic h was

formed when t h e low c e n t r a l p o r t i o n o f t h e Lower M i s s i s s i p p i

A l l u v i a l V a l l e y became c o m p l e t e l y su r r o u n d e d by n a t u r a l

l e v e e r i d g e s b u i l t by v a r i o u s M i s s i s s i p p i R i v e r c o u r s e s

( F i s k , 1 9 5 2 ) , c o n t a i n s many l a k e s ( e . g . , Grand Lake, S i x

M i l e L ake, Lake F a u s s e F o i n t e ) t h a t are rem nan ts o f a much

l a r g e r body o f w a t e r . The e x i s t e n c e o f t h e s e e x t e n s i v e

l a k e s makes i t v e r y d i f f i c u l t t o t r a c e t h e a n c i e n t l e v e e

s y s t e m s , nor th w ard from t h e Teche a c r o s s t h e lo w , p r e s e n t l y

r a p i d l y a l l u v i a t i n g , b a s i n . N e v e r t h e l e s s , some e v i d e n c e

s u g g e s t i v e o f a c o n t i n u a t i o n o f t h e S a l e s y s t e m n o r t h o f the

T ech e l e v e e s d o e s e x i s t .

A p o s s i b l e i n d i c a t i o n o f t h e Bayou S a l e ’ s y s t e m n o r t h

o f t h e Teche r i d g e i s foun d i n C a t h c a r t ' s ( 1 8 1 9 ) w ork . H is

map, w h i l e n o t a c c u r a t e s o f a r a s d i s t a n c e i s c o n c e r n e d , can

c e r t a i n l y be r e l i e d upon a s t o r e l a t i v e p o s i t i o n s o f v a r i o u s

f e a t u r e s . C a t h c a r t shows a s m a l l bayou r u n n i n g a p p r o x i m a t e l y

108

n o r t h e a s t w a r d from t h e T eche r i d g e . T h i s f a c t i n i t s e l f i s

n o t i m p o r t a n t f o r t h e ba y ou i s p r o b a b ly known on modern quad

r a n g l e s a s t h e more e a s t e r l y f l o w i n g Y e l l o w Bayou; how ev er ,

C a t h c a r t ( p . 37) m e n t i o n s t h a t a s h e l l midden i s l o c a t e d a t

t h e mouth o f t h i s b a y o u . T h i s s h e l l a c c u m u l a t i o n w o u ld ,

t h e r e f o r e , be l o c a t e d w e l l o f f t h e Teche l e v e e s and t o t h e

e a s t o f t h e l a r g o bend i n t h e Teche ( F i g . 2 ) , i n o t h e r

w ords , p r a c t i c a l l y o p p o s i t e t h e S a l e ’ -T e ch e j u n c t i o n . The

p r e s e n c e o f t h i s midden i s s u g g e s t i v e o f a more im p o r t a n t

s tr ea m than t h e i n s i g n i f i c a n t modern Y e l l o w Bayou.

A n o r th w ard c o n t i n u a t i o n o f t h e Bayou S a l e ’ s y s t e m

i s a l s o s u g g e s t e d by t h e c o n v e x -n o r th w a r d bend i n Y e l l o w

Bayou, which p o s s i b l y i n d i c a t e s a b u r i e d l e v e e r i d g e . The

broad n or thw ard b u l g e i n th e c u l t i v a t e d a r e a a l o n g t h e Teche

i n t h i s r e g i o n i s a l s o i n d i c a t i v e . U n f o r t u n a t e l y , more r e

c e n t a l l u v i a t i o n by t h e T e c h e - M i s s i s s i p ] ; ! h a s masked m ost

o f t h e o l d e r d e p o s i t s n ear t h e Teche r i d g e , h o w ev er , a e r i a l

p h o t o g r a p h s r e v e a l a northw ard t r e n d i n g t o n a l band t h a t

c o u l d e a s i l y r e f l e c t b u r ie d n a t u r a l l e v e e s ( F i g . 2 1 ) . The

1841 meander l i n e ( o l d s h o r e l i n e ) shown on modern quadran

g l e s i s a l s o i n d i c a t i v e a s i t shows t h a t t h e sh o r e o f S i x

M il e Lake h a s r e t r e a t e d on both s i d e s o f t h i s t o n a l band;

w h e r e a s , a s l i g h t p r o m i t o r y has d e v e l o p e d where t h e band

i n t e r s e c t s t h e l a k e s h o r e . In a d d i t i o n , t h e f a c t t h a t t h e

Bayou S a l e ’ d i s t r i b u t a r y branched from t h e T e c h e - M i s s i s s i p p i

109

on t h e i n s i d e o f a bend i s p o s s i b l y i n d i c a t i v e o f a n e a r s u r

f a c e n o r t h - n o r t h e a s t t o s o u t h - s o u t h w e s t t r e n d i n t h e j u n c t i o n

a r e a . Normal c r e v a s s e ch a n x ie ls , w h ic h g i v e r i s e t o d i s t r i b u

t a r i e s o f any im p o r t a n c e , are i n v a r i a b l y formed on t h e o u t

s i d e o f b e n d s .

I t s h o u l d be p o i n t e d o u t t h a t d u r i n g t h e t i m e t h e

Bayou S a le * d i s t r i b u t a r y o f t h e T e c h e - M i s s i s s i p p i was o p e r a

t i v e t h e r e was l i t t l e c h an ce f o r a s e c o n d im p o r t a n t d i s

c h a r g e c h a n n e l t o d e v e l o p i n t h e o t h e r l e v e e o p p o s i t e t h e

f i r s t . Thus t h e p o s s i b i l i t y t h a t a nor thw ard t r e n d i n g l e v e e

r i d g e o f any l e n g t h , n o r t h o f t h e Teche r i d g e n e a r t h e S a l e T-

Teche j u n c t i o n , would r e f l e c t a d i s t r i b u t a r y o f t h e T e c h e -

M i s s i s s i p p i i s v e r y r e m o t e . T y p i c a l s h o r t - l i v e d , b i f u r c a t

i n g , c r e v a s s e c h a n n e l s and t h e i r f a n - s h a p e d d e p o s i t s were

u n d o u b t e d ly formed a l o n g t h e n o r t h e r n T e c h e - M i s s i s s i p p i

l e v e e ; hovxever, s t r e a m s o f t h i s t y p e u s u a l l y do n o t form

l e v e e r i d g e s w h ic h e x t e n d f o r any d i s t a n c e away from t h e

main c o u r s e .

Thus e v i d e n c e seem s t o i n d i c a t e an e x t e n s i o n o f t h e

Bayou S a l e ’ s y s t e m n o r t h o f th e Teche r i d g e . I t s p o s s i b l e

c o n t i n u a t i o n t o t h e n o r t h e a s t o f Grand Lake ( P l a t e I , F i g . d)

i s more d i f f i c u l t t o a s c e r t a i n . A p r o l o n g a t i o n o f t h e Bayou

S a le * s y s t e m i n t e r s e c t s t h e e a s t e r n sh o r e o f Grand Lake

s l i g h t l y b e lo w t h e mouth o f B i g Bayou P i g e o n ( P l a t e I , F i g .

a) . C o n s i d e r i n g B i g Bayou P ig e o n t o be t h e n o r t h e r n

110

e x t e n s i o n o f t h e s y s t e m , th ou g h s p e c u l a t i v e , i s c e r t a i n l y

a t t r a c t i v e . The bayou h a s broad n a t u r a l l e v e e s t h a t , b e f o r e

man and s u b s i d e n c e t o o k t h e i r t o l l , s u p p o r t e d a f i n e growth

o f o a k . Thus i t p o s s e s s e s many a t t r i b u t e s o f a more im por

t a n t s t r e a m t h a n i t s p r e s e n t d e g e n e r a t e c o n d i t i o n i n d i c a t e s .

The p r e s e n c e o f p r e - T c h e f u n c t e a r t i f a c t s i n m idd en s a l o n g i t s

l e v e e s (V/m. M c l n t i r e - - p e r s o n a l c o m m u n ic a t io n ) i s an i n d i c a

t i o n o f g r e a t a n t i q u i t y . A l l i n a l l , B ig Bayou P i g e o n m e e ts

th e r e q u i r e m e n t s f o r t h e e x t e n s i o n o f t h e Bayou S a l e ’ s y s t e m

and w i l l be t e n t a t i v e l y c o n s i d e r e d a s s u c h i n t h i s r e p o r t

( P l a t e I , F i g . a ) . 21

F i s k ( 1 9 5 2 , F i g . 1 4 ), a s p r e v i o u s l y p o i n t e d o u t , shows

Bayou S a l e ’ a s a d i s t r i b u t a r y o f h i s M a r in g o u in s y s t e m . The

M a r in g o u in c o u r s e , a s shown on F i s k ' s ( 1 9 5 2 ) F i g u r e 1 4 , i s

n o t t h e same M a r in g o u in c o u r s e p r e s e n t e d i n h i s 1944 ( P l a t e

2 , S h e e t 2) r e p o r t . In a d d i t i o n , F ig u r e 14 o f t h e 1952 r e

p o r t makes no i n d i c a t i o n o f t h e C o c o d r ie c o u r s e , w h ich was

i l l u s t r a t e d as s u b s e q u e n t t o t h a t o f the M a r in g o u in i n t h e

e a r l i e r w ork . See F i g . 18b f o r F i s k ' s 1944 c h r o n o l o g y .

C o n s e q u e n t l y , th e o n l y c o r r e l a t i o n t h a t can be made i s t o

21 Bore h o l e s put down on C y p r e s s I s l a n d ( F i g . 2) and a l o n g t h e w e s t e r n s h o r e o f T i g e r I s l a n d , p l u s t h e a l i g n m e n t o f a f e w , s c a t t e r e d , oak t r e e s seem t o i n d i c a t e t h a t t h e t r e n d o f t h e o l d s t r e a m c o u r s e s i n t h e a r e a was i n a N-S t o hMi-SSE d i r e c t i o n . In o t h e r w o r d s , no e a s t w a r d t u r n i n g o f t h e Bayou S a le * t r e n d n o r t h o f t h e Teche R id g e was f o u n d .

I l l

c o n c lu d e t h a t t h e Bayou S a l e ' s y s t e m i s a p a r t o f F i s k ’ s

M a r i n g o u in - C o c o d r ie c o m p lex .

P l a t e I ( F i g . a ) i n d i c a t e s t h e c o u r s e s and d e l t a i c

a r e a s o f t h e Bayou S a l e 1 s y s t e m . The e a r l i e s t c o u r s e s , 1

and 2 , were p r o b a b l y , i n p a r t , c o e v a l and u n d o u b t e d ly r e

c e i v e d some f l o w w h i l e c o u r s e 3 was o p e r a t i n g a s t h e main

c h a n n e l . ( I t s h o u l d be borne in mind t h a t f l o w down o l d

r i v e r c o u r s e s i s n o t a b r u p t l y c u t o f f , and t h a t many o l d

c h a n n e l s c o n t i n u e t o r e c e i v e w a t e r , p a r t i c u l a r l y f l o o d w a t e r ,

l o n g a f t e r t h e y c e a s e t o f u n c t i o n a s main r i v e r c h a n n e l s . )

S h o r e l i n e s a r e t e n t a t i v e l y shown. S e v e r a l bore h o l e s on

w e s t e r n Marsh I s l a n d e n c o u n t e r e d buy bo t to m sa n d s a t a

d e p th o f a p p r o x i m a t e l y t w e n t y - t w o f e e t . The f e a t h e r ed g e

o f t h i s sa n d l a y e r , w h ic h r i s e s and p i n c h e s o u t t o t h e e a s t ,

p o s s i b l y a p p r o x i m a t e s t h e o l d s h o r e l i n e o f t h e c o u r s e 3

d e l t a , and was assum ed t o do so i n th e f i g u r e . The e a r l i e r

s h o r e l i n e i s p u r e l y h y p o t h e t i c a l .

From t h e p r e c e d i n g p a g e s , i t i s a p p a r e n t t h a t t h e

Bayou S a l e ’ s y s t e m p o s s e s s e s a r e l a t i v e l y com p lex h i s t o r j ' ,

c e r t a i n p o r t i o n s o f which a re s t i l l i n d o u b t . Bayou S a le *

and Bayou Cyprem ort , w h ic h w i l l be d i s c u s s e d in the f o l l o w

i n g s e c t i o n , have p r e v i o u s l y r e c e i v e d v e r y l i t t l e g e o l o g i c

a t t e n t i o n and i t s h o u l d be em p h a s iz e d t h a t t h e m a t e r i a l

p r e s e n t e d i n t h i s r e p o r t i s b u t a s t a r t in t h e i n t e r p r e t a

t i o n o f t h e i r r e s p e c t i v e h i s t o r i e s .

Bayou Cypremort

A l t h o u g h t h e e a r l y l i t e r a t u r e d o e s n o t abound w i t h

d e s c r i p t i o n s o f Bayou C yprem ort , a f e w r e f e r e n c e s have been

f o u n d . I l i l g a r d ( 1 8 7 3 , p . 7 ) m e n t i o n s t h e n a t u r e and f e r t i l i

t y o f t h e s o i l a l o n g t h e b a y o u . D e n n e t t ( 1 8 7 6 , p . 101) i n

d e s c r i b i n g t h e r e g i o n s t a t e s ;

The r o a d l e a d i n g th r o u g h t h e s e e n c h a n t e d f o r e s t s (Cypremort W oods) , a l o n g t h e banks o f t h e ba yo u , i s f i r m , smooth and s a n d y . The bayou i t s e l f i s by no means b e a u t i f u l , s i n c e i t i s u s u a l l y f i l l e d w i th r a n k w e e d s , r u s h e s , w i l l o w s and numerous o t h e r t r e e s and b u s h e s p e c u l i a r t o t h e s e s h a l l o w and narrow b a y o u s . I t can in no p l a c e be n a v i g a t e d w i t h a s k i f f .

P e r r i n ( 1 8 9 1 , p . 214) o b s e r v e s ;

The Bayou Cypremort i s l i n e d w i t h b e a u t i f u l f o r e s t s , o f w h ic h t h e s t a t e l y m a g n o l ia p r e d o m i n a t e s . Many o f them o v e r f i f t y f e e t h ig h . . . But m i n g l e d w i t h t h e m a g n o l ia a l o n g Cypremort a r e o ak , a s h , b l a c k w a l n u t , h i c k o r y , s w e e t gum, p e c a n , e lm , e t c . , w i t h a ra n k grow th o f underbru sh and g r a p e v i n e s . There i s n o t h i n g v e r y b e a u t i f u l and e n c h a n t i n g i n the bayou a s a s t r e a m , i t b e i n g f i l l e d w i t h w e e d s , r u s h e s , and w i l l o w s , a s e e m in g hau nt f o r s n a k e s and o t h e r w a te r r e p t i l e s .

The same d e s c r i p t i o n s f i t t h e bayou t o d a y , f o r i t h a s

been d e e p e n e d o n l y n e a r i t s mouth where ei d o c k i n g a r e a f o r

p l e a s u r e b o a t s has been c o n s t r u c t e d . A narrow band o f w ood s ,

a b o u t f o u r m i l e s i n l e n g t h , f l a n k i n g t h e bayou n e a r i t s

mouth i s a l l t h a t r e m a i n s o f t h e m a g n i f i c e n t f o r e s t s d e s

c r i b e d by t h e e a r l y w r i t e r s .

R e f e r e n c e s t o Bayou S a l e ' h a v e been fou n d a s f a r back

a s 1802 ( S t . Mary P a r i s h P l a n n i n g B oard , 1 9 4 9 , p . 7 ) w h i l e

C yprem ort , due t o i t s l a t e r s e t t l e m e n t , r e c e i v e d no m e n t io n

113

u n t i l 1813 ( S u r v e y o f F e d e r a l A r c h i v e s i n L o u i s i a n a , Book I ,

P a r t 2 , A ta k a p a s R e g io n , 19 39)* The e a r l i e s t p h y s i o g r a p h i c

d e s c r i p t i o n s o f Cypremort a r e foun d i n t h e 1 8 7 0 ’ s , w h ereas

S a l e 1 was d e s c r i b e d us e a r l y a s 1819 ( C a t h c e r t , p . 9 8 )* How

e v e r , t h e a s s u m p t io n t h a t Cyprem ort , l i k e S a l e ’ , r e c e i v e d no

through f l o w d u r i n g h i s t o r i c t i m e s i s v a l i d .

The r e c e n t g e o l o g i c l i t e r a t u r e i s a l m o s t c o m p l e t e l y

l a c k i n g in r e f e r e n c e s to. Bayou Cyprem ort . F i s k ( 1 9 4 4 , P l a t e

15) p l a c e s t h e bayou i n s t a g e 2 o f h i s c h r o n o l o g y , but d o e s

n o t m en t io n i t i n th e t e x t . T h i s s t a g e 2 c l a s s i f i c a t i o n

i n d i c a t e s t h a t he c o n s i d e r s t h e s t r e a m t o be a d i s t r i b u t a r y

o f t h e T e c h e - I v l i s s i s s i p p i .

That Bayou Cypremort was n e v e r a v e r y im p o r ta n t

stream i s a t t e s t e d t o by ( 1 ) the r e l a t i v e l y s m a l l d e l t a i c

a r e a t h a t can be a s c r i b e d to i t , ( 2 ) t h e p r e s e n c e o f o n l y

s m a l l b u r i e d d i s t r i b u t a r i e s in no way com parable w i t h t h o s e

o f the Bayou S a l e 1 s y s t e m , and (3 ) t h e s i z e o f i t s l e v e e s

( F i g . 1 9 b ) . The f a c t t h a t t h e l e v e e s o f Cypremort, j u s t

s o u t h o f t h e Teche r i d g e , a r e 2’e s t r i c t e d t o a narrow c u t

through t h e P l e i s t o c e n e P r a i r i e T e rr a ce ( F i g . 4 ) i n d i c a t e s

t h a t t h e p r e s e n t l e v e e s do n o t mask a more im p o r ta n t s t r e a m

u s in t h e c a s e o f Bayou S a l e ’ .

Bore h o l e s and a e r i a l p h o to g ra p h s show c l e a r l y t h a t

Bayou Cypremort branched r e p e a t e d l y i n t h e V e r m i l io n Bay

a r e a . The e x t e n s i o n o f t h e bayou westw ard from Cypremort

' 114

P o i n t i s e a s i l y p l o t t e d by f o l l o w i n g t h e s h o a l a r e a known a s

T e r r a p in R e e f (USC&GS Chart 1 2 7 7 ) . T h i s t r e n d i n t e r s e c t s

t h e n o r t h e r n sh o r e o f Marsh I s l a n d a b o u t a m i l e w e s t o f th e

mouth o f Bayou Chene. Bore h o l e s put down a t t h e p o i n t

where t h i s t r e n d i n t e r s e c t s t h e bayou e n c o u n t e r e d l e v e e

m a t e r i a l a t a d e p th o f t h r e e f e e t . Numerous o t h e r s m a l l

d i s t r i b u t a r i e s o f Bayou Cypremort u n d o u b t e d ly c r o s s Marsh

I s l a n d ; h ow ever , t h e e x a c t p o s i t i o n s c a n n o t be p l o t t e d a t

t h e p r e s e n t t i m e . C u rren t work by Kdwerd Orton i n t h i s a r e a

may p r o v i d e a d d i t i o n a l d a t a . O x id i z e d s i l t y c l a y , i n t e r

p r e t e d a s l e v e e m a t e r i a l , fo u n d a l o n g t h e s o u t h w e s t e r n c o a s t

o f Marsh I s l a n d , o r i g i n a l l y c o n s i d e r e d t o be p o s s i b l e e x t e n

s i o n s o f t h e Bayou B u ie ' s y s t e m (Morgan, Van L o p ik , and

N i c h o l s , 1 9 5 3 , pp . 6 - 8 ) p r o b a b l y b e l o n g s , i n t h e l i g h t o f

l a t e r f i e l d work, to t h e Cypremort s y s t e m . However, t h e

e v i d e n c e i s s t i l l i n c o n c l u s i v e .

The NE-SVJ t r e n d i n g l e v e e s t h a t i n t e r s e c t t h e s o u t h

sh o r e o f V e r m i l io n Bay a p p r o x i m a t e l y two m i l e s e a s t o f H e l l

H o le u n d o u b t e d ly r e p r e s e n t a n o t h e r d i s t r i b u t a r y o f th e

Cypremort s y s t e m . P i g . 23a shows a b ore h o l e p r o f i l e o f

t h e s e o x i d i z e d l e v e e s . The s h e l l - s a n d bay bo t to m l a y e r ,

a c r o s s which th e s t r e a m p r o g r a d e d , l i e s fit un a v e r a g e d e p th

o f t w e n t y - f i v e f e e t . T h i s zone may c o r r e s p o n d t o t h e bay

b o ttom s a n d s found u n d e r l y i n g t h e w e s t e r n p o r t i o n o f Marsh

I s l a n d a t a d e p th o f t w e n t y - t w o f e e t . N ote a l s o t h a t t h e

115

t o t a l w id t h o f th e o x i d i z e d zone f o r b o t h l e v e e 3 s h o u ld e x

c e e d 3 , 0 0 0 f e e t . In s p i t e o f t h i s f a c t , numerous h o l e s a l o n g

th e e a s t e r n s h o r e o f H e l l H o le , where t h e s c a r can a p p a r e n t l y

be t r a c e d on a e r i a l p h o t o g r a p h s , r e v e a l o n l y r e l a t i v e l y n a r

row d i s c o n t i n u o u s bands o f o x i d a t i o n i n d i c a t i v e o f l e v e e d e

p o s i t s ( F i g . 2 3 b ) . The c o n c l u s i o n t h a t t h e bayou h a s b i f u r

c a t e d b e f o r e r e a c h i n g H e l l H o le i s i n e s c a p a b l e . S e v e r a l

p o s s i b l e c o u r s e s s u g g e s t t h e m s e l v e s from an e x a m i n a t i o n o f

a e r i a l p h o t o g r a p h s , how ever d e f i n i t e f i e l d e v i d e n c e o f t h e s e

c o u r s e s i s l a c k i n g .

A s m a l l e r branch o f Cypremort a p p a r e n t l y c o n t i n u e s to

t h e w e s t o f H e l l H o l e . However, a w e l l d e f i n e d t o n a l band,

s o d i s t i n c t on a e r i a l p h o t o g r a p h s , t r e n d i n g from H e l l H ole

to t h e C h en ie r au T i g r e r e g i o n d o e s n o t r e f l e c t an o l d chan

n e l . Two bore h o l e p r o f i l e s ( F i g . 23c and d) prov e c o n c l u

s i v e l y t h a t , a l t h o u g h the r e g i o n was p r o b a b ly t h e s i t e o f

d e l t a i c s e d i m e n t a t i o n , t h i s t o n a l band d o e s n o t o v e r l i e

l e v e e o r c h a n n e l f i l l d e p o s i t s . T r a c e s o f s e v e r a l o l d ,

n o r t h w e s t t r e n d i n g , s h o r e l i n e s c r o s s th e a r e a t o the e a s t o f

C h e n ie r au T i g r e , t h e r e f o r e , i t i s p o s s i b l e t h a t th e l e v e e s

a t one t i m e d i d e x te n d i n t o t h i s r e g i o n , and were s u b s e

q u e n t l y t r u n c a t e d by s h o r e l i n e r e t r e a t . A s t u d y o f a e r i a l

p h o t o g r a p h s and bore h o l e i n f o r m a t i o n ( F i g . 2 3 ) i n d i c a t e s

t h a t o n l y t h e v e r y d i s t a l p o r t i o n o f t h e s t r e a m s o r s t r e a m

r e a c h e d th e C h e n ie r au T ig r e r e g i o n a n d , t h e r e f o r e , t h e r e

t r e a t i n g s h o r e l i n e d id n o t t r u n c a t e a l e v e e s y s t e m o f any

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m a g n i t u d e . On t h e o t h e r h a n d , t h e r e i s a p o s s i b i l i t y t h a t

t h e m a i n s t r e a m t u r n e d s o u t h e a s t w a r d e a s t o f H e l l H o l e . Thus

i t s d i s t a l p o r t i o n would h a v e b e e n t r u n c a t e d b y t h e p r e s e n t

s h o r e l i n e a t t h e G u l f o f M e x i c o ( P l a t e I , F i g . b ) . S c a t t e r e d

b o r i n g s w e r e made a l o n g t h e p r e s e n t s h o r e i n a n e f f o r t t o

l o c a t e t h e p o i n t a t w h i c h ( i f t h e a b o v e h y p o t h e s i s i s c o r r e c t )

t h e l e v e e s w o u l d ha v e b e e n t r u n c a t e d by t h e p r e s e n t g u l f

s h o r e ; h o w e v e r , no e v i d e i ; c e o f t h i s p o s s i b l e s o u t h e r n e x

t e n s i o n was f o u n d .

T h e r e a r e some d a t a s u g g e s t i n g t h a t C y p r e m o r t i s

y o u n g e r t h a n t h e Bayou Sa l e * s y s t e m . A b o r i n g made n e a r

Mound F o i n t , M a r s h I s l a n d , e n c o u n t e r e d v / e l l p r e s e r v e d wood

f r a g m e n t s a n d l o g s a t t w e n t y - f i v e t o t w e n t y - n i n e f e e t , a f t e r

p a s s i n g t h r o u g h a p p r o x i m a t e l y f o u r f e e t o f c o m ; a c t p e s t .

T h i s s e q u e n c e s u g g e s t s a r e l a t i v e s u b s i d e n c e o f t h e l a n d

w i t h t h e woody zone p o s s i b l y r e p r e s e n t i n g t h e b a c k swamp

r e g i o n o f t h e Eayou S a l e * s y s t e m , f o r m a l a s B u i e ' ( C o u r s e

3 , P l a t e I , F i g . a ) p r o g r a d e d w e s t w a r d a c r o s s t h e embayment

w h i c h f o r m e r l y e x i s t e d i n t h e m a r s h I s l a n d a r e a . S e v e r a l

b o r i n g s on t h e e a s t e r n h a l f o f *-arsh I s l a n d r e v e a l o r a t h e r

I r r e g u l a r l y o c c u r r i n g s a n u l a y e r a t a p p r o x i m a t e l y t w e n t y - s i x

f e e t , w h i c h p o s s i b l y r e p r e s e n t s t h e b o t t o m o f t h e embaymen t .

A d d i t i o n a l b o r i n g s i n d i c a t e t h a t t h i s l a y e r i s n o t c o n t i n u

o u s w i t h t h e t w e n t y - t w o f o o t s a n d w h i c h u n d e r l i e s t h e w e s t

e r n h a l f o f t i i e i s l a n d . As p r e v i o u s l y p o i n t e d c u t , Bayou

C y p r e m o r t p r o b a b l y p r o g r a d e d a c r o s s a c o n t i n u a t i o n o f t h e

118

t w e n t y - t w o f o o t s a n d , t h u s , i t i s s u g g e s t e d t h a t C y p r e m o r t ,

by i t s s t r a t i g r a p h i c p o s i t i o n , i s y o u n g e r t h a n S a l e ! A s u f

f i c i e n t number o f b o r i n g s i s n o t a v a i l a b l e t o a l l o w d e f i n i t e

c o r r e l a t i o n b e t w e e n t h e H e l l H o l e , H a r s h I s l a n d , a n d Bayou

S a l e ’ a r e a s a n d , t h u s u n r e s e r v e d a c c e p t a n c e o f t h e a b o v e

h y p o t h e s i s i s i m p o s s i b l e . F u r t h e r f i e l d work w i t h t h i s

s t r a t i g r a p h i c r e l a t i o n i n m in d , h o w e v e r , may p r o v e e d i f y i n g .

I t i s a l s o i n t e r e s t i n g t o n o t e t h a t a t o n l y two

l o c a l i t i e s i n c e n t r a l c o a s t a l L o u i s i a n a hav e I n d i a n p r o j e c t i v e

p o i n t s b e e n f o u n d , thio Qf t h e s e s i t e s l i e s a b o u t two m i l e s

e a s t o f H e l l Ho l e on l e v e e d e p o s i t s o f C y p r e m o r t o r i g i n ; t h e

o t h e r i s u b e a c h a c c u m u l a t i o n , l o c a t e d on R a b b i t I s l a n d ,

o v e r l y i n g l e v e e s o f t h e Bayou H a l e ’ s y s t e m . The p r o j e c t i l e

p o i n t s a r e s u g g e s t i v e o f p r e - T c h e f u n c t o a g e . The f a c t s t h a t

p r e - f c h e f u n c t e a r t i f a c t s h a v e been f o u n d on c o u r s e s 1 and 2

( P l a t e I , F i g . a ) o f t h e Bayou B a l e ' s y s t e m ; p r o j e c t i l e

p o i n t s h a v e be en f o u n d on c o u r s e 3 o f t h e Bayou S a l e ’ s y s

t em; and p r o j e c t i l e p o i n t s an d T c l ^ e f u n c t e p o t s h e r d s h a v e

be en f o u n d a l o n g Bayou CyJ.-i*emort s u g g e s t a g r a d u a l w e s t w a r d

movement o f d e l t a i c s e d i m e n t a t i o n . I t i s a l s o a : p a r e n t

t h a t a f t e r t h e f o r m a t i o n o f t h e d e l t a i c a r e a t o t h e s o u t h

w e s t o f M a r s h I s l a n d t h e mos t l o g i c a l r e g i o n f o r f u r t h e r

s e d i m e n t a t i o n w o u l d be i n t h e d e l t a - f l a n k d e p r e s s i o n n o r t h

o f t h e Bayou S a l e ’ d e l t a , a n d s o u t h o f t h e P l e i s t o c e n e o u t

c r o p — a p o s i t i o n o c c u p i e d by Bayou C y p r e m o r t . The p r e c e d i n g

119

d i s c u s s i o n , o f c o u r s e , s t i l l l e a v e s t h e r e l a t i v e a g e s o f

Cypremort and Sa le* somewhat in d o u b t . H ow ever , a v a i l a b l e

d a t a seem t o i n d i c a t e t h a t Cypremort i s d e f i n i t e l y y o u n g er

t h a n th e 1 and 2 c o u r s e s o f t h e Bayou S a le * s y s t e m and

p r o b a b l y y o u n g er th an c o u r s e 3 (I’l a t e I , B i g . a ) . The c o n

c e p t t h a t Cypremort and c o u r s e 3 o f t h e S a l e ’ s y s t e m w e r e ,

i n p a r t , c o e v a l , a l t h o u g h d o u b t f u l , c a n n o t be d i s c a r d e d .

The w r i t e r l i a s i g n o r e d t h i s p o s s i b i l i t y o n l y b e c a u s e t h e r e

a r e no f a c t s a v a i l a b l e , a t t h e p r e s e n t t i m e , t o s u p p o r t t h i s

c o n t e n t i o n . T h i s l a c k o f e v i d e n c e , o f c o u r s e , i n no w a y d i s

p r o v e s t h e t h e o r y . The f i n d i n g o f p r o j e c t i l e p o i n t s on t h e

e x t e n s i o n o f C y p r e m o r t n e a r H e l l H o l e s u g g e s t s t h a t by p r e -

o r e a r l y - T c h e f u n c t c t i m e t h e s t r e a m was w e l l e s t a b l i s h e d an d

f l a n k e d by h a b i t a b l e l e v e e s . I f t h e c h r o n o l o g i e s e s t a b l i s h e d

by F i s k an d P h i l l i p s , F o r d , and C r i f f e n ( F i g . 18b) a r e a c

c e p t e d t h e Tec he c o u r s e was n o t e s t a b l i s h e d u n t i l T c h e f u n c t e

t i m e , t h u s s u g g e s t i n g t h a t C y p r e m o r t i s o l d e r t h a n t h e T e c h e -

M i s s i s s i p p i . F u r t h e r m o r e , t h e r e i s a p p a r e n t l y an e x t e n s i o n

o f Bayou C y p r e m o r t t o t h e n o r t h o f t h e Teche r i d g e . F i g . 24

shows t h e a l m o s t p e r f e c t a l i g n m e n t o f Bayou C y p r e m o r t w i t h

t h i s n o r t h w a r d p r o j e c t i n g f i n g e r o f high, g r o u n d w h i c h c a n be

t r a c e d to t h e s o u t h e r n s h o r e o f Lake F a u s s e B o i n t e . I f

Bayou C y p r e m o r t hud o r i g i n a t e d a s a d i s t r i b u t a r y o f t h e

T e c h e - I d i s s i s s i p p i l i i v e r i t i s h i g h l y i m p r o b a b l e t h a t a s i m i

l a r d i s t r i b u t a r y wou ld f o r m on t h e o p p o s i t e s i d e o f t h e

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i ' V - O - o ' , * ■ i * • ' V 7 V ; ^ ' V T , v . , ' v * *. » V , ^ ' v \

• ?•••• •'*'•' v1 ■■.*

F ig u r e 24 - C y p rem o rt -T ech e J u n c t i o n Area

I| 120 ♦* F i g u r e 2 4 - C y p r e m o r t - T e c h e J u n c t i o n A r e a

121

r i v e r . P r o f i l e s o f t h e n or thw ard t r e n d i n g o x i d i z e d l e v e e

r i d g e ( P r o f i l e s 1 and 2 , F i g s . 19 and 20) i n d i c a t e t h a t i t

has been p a r t i a l l y d e s t r o y e d by e r o s i o n . T h is m o d i f i c a t i o n

i s p r o b a b l y t h e r e s u l t o f wave a c t i o n a t a t i m e , p r e v i o u s

t o t h e b r e a c h i n g o f t h e T e c h e - H i s s i s s i p p i r i d -e by w a t e r s o f

the A t c h a f a l a y a B a s i n , when Lake F au sae P o i n t e was more e x

t e n s i v e th a n a t t h e p r e s e n t t i m e .

I t s h o u l d be p o i n t e d o u t , t h u t a c c e p t i n g t h e p r e -

Teche a g e o f Cypremort d o e s n o t im p ly t h a t t h e r e was no

T e c h e - m i s s i s s i p p i f l o w down t h e b a y o u , i n f a c t , w e l l p r e

s e r v e d c r e v a s s e p a t t e r n s a r e d i s c e r n i b l e on th e Cypremort

l e v e e s t h u s s u g g e s t i n g th r o u g h f l o w d u r i n g T e c h e - M i s s i s s i p p i

t im e (S e e T ech e-Iv i iss i s s i p p i s e c t i o n f o r f u r t h e r d i s c u s s i o n ) .

C o n n e c t i n g Cypremort w i t h i t s t r u n k s t r e a m n o r t h o f

Lake F a u s s e P o i n t e p r e s e n t s somewhat o f a problem a s more

r e c e n t s e d i m e n t a t i o n i n t h i s a r e a has masked t h e e a r l i e r«

s t r e a m c o u r s e s . The o n l y s u g g e s t i o n t h a t can be made a t t h e

p r e s e n t t im e i s t h a t Bayou S o r r e l l forms t h e n o r t h e r n con

t i n u a t i o n o f Cypremort. T h i s s u p p o s i t i o n i s b a s e d e n t i r e l y

on c u l t u r u l e v i d e n c e which s u g g e s t s t h a t Bayou S o r r e l l i s

t h e same a p p r o x im a t e a ge a s Bayou Cypremort. (Wm. lv lc ln t i r e

h a s foun d P o v e r t y P o i n t a r t i f a c t s a l o n g Bayou S o r r e l l -

p e r s o n a l c o m m u n ic a t io n ) .

P l a t e I ( F i g . b) a t t e m p t s t o summarize t h e a v a i l a b l e

i n f o r m a t i o n on Bayou Cyprem ort, sh o w in g i t s o r i g i n a l c o u r s e ,

122

b r a n c h e s , d e l t a i c a r e a , and t h e r e l a t i v e p o s i t i o n o f t h e

s h o r e l i n e a t t h a t t i m e . Bayou S o r r e l l i s t e n t a t i v e l y c o n

s i d e r e d t o be t h e p r o l o n g a t i o n a t Cypremort n o r t h o f l a k e

F a u s s e P o i n t e .

B e f o r e c o n c l u d i n g t h i s s e c t i o n m e n t io n s h o u l d be made

o f t h e m o d i f i c a t i o n s a f f e c t e d i n t h e l e v e e s o f Bayous Cypre

mort and S a l e ' by movement a l o n g t h e F i v e I s l a n d f a u l t z o n e .

As .'’o r g a n , Van Lopilc, and N i c h o l s ( 1 9 5 3 , p . U) have p o i n t e d

o u t , "The p r e s e n c e o f t h i s f a u l t h a s n o t b e e n d e f i n i t e l y

e s t a b l i s h e d , b u t i s s u g g e s t e d by s e v e r a l l i n e s o f e v i d e n c e :

( 1 ) th e s p e c i f i c o r i e n t a t i o n o f a l l f i v e o f t h e s a l t domes,

( 2 ) narrovJing o f t h e n a t u r a l l e v e e s o f Bayou S a l e ’ s o u t h o f

Gordy, L o u i s i a n a , and ( 3 ) n a r r o w in g o f t h e n a t u r a l l e v e e s

o f Buyou Cypremort a t t h e town o f Cyprem ort , L o u i s i a n a . "

P r o f i l e s 8 , 9 , and 10 ( F i g . 19) g r a p h i c a l l y i l l u s t r a t e th e

e f f e c t on Cypremort l e v e e s o f th e r e l a t i v e downdropping o f

th e la n d s o u t h w e s t o f t h e f u u l t . These f a c t s a t t e s t t o th e

r e c e n c y o f movement a l o n g t h i s f a u l t z o n e , i n a d d i t i o n ,

o t h e r d a ta i n d i c a t e t h a t th e s u i t m a s s e s f o r m in g t h e c o re o f

th e F i v e I s l a n d s a r e s t i l l r i s i n g . V / e i g e l t ( 1 9 2 7 , p . k l )

makes t h e f o l l o w i n g o b s e r v a t i o n ( t r a n s l a t e d from th e German),

. . t h e i r ( t h e F i v e I s l a n d s ) yo u n g u p l i f t becomes d o c u

mented by t h e f a c t t h a t t h e r o c k s a l t , i n s p i t e o f t h e m o i s t

c l i m a t e , comes up n i n e m e t e r s a b o v e t h e p r e s e n t s u r f a c e . "

V /e ig e l t* s o b s e r v a t i o n in r e g a r d t o t h e e f f e c t o f c l i m a t e on

123

t h e s a l t i s w e l l f o u n d e d f o r t h e r e cun be l i t t l e do u bt t h a t

under a r i d c o n d i t i o n s t h e F i v e I s l a n d would g i v e r i s e t o

phenom enal s a l t m o u n t a in s and g l a c i e r s su c h a s a r e found i n

I r a n t o d a y . T h us , t h e t r u n c a t i o n o f t h e l e v e e s o f B a yo u s

Cypremort and S a l e * , and t h e e l e v a t i o n o f pure s a l t a b o u t

t w e l v e f e e t ( V / e i g e l t * s n i n e m e t e r f i g u r e i s s l i g h t l y h i g h )

ab ov e t h e p r e s e n t s u r f a c e , i n t h e m o i s t c l i m a t o o f L o u i s i a n a ,

c e r t a i n l y a t t e s t s t o t h e r e c e n c y o f a c t i v i t y a l o n g t h i s

t r e n d .

Bayou Teche and V e r m i l i o n

The r e g io n ' s m ost i m p o r t a n t a r t e r y o f t r a v e l d u r i n g

t h e e a r l y d a y s was t h e w e l l - k n o w n Bayou T e c h e . T hus , t h e

lo g ic a l early habitation s i t e s were on the levees o f th is

bayou, and consequently, by 1800 m ost o f thG land f l a n k i n g22Bayou Teche had b e e n s u r v e y e d .

I n d e e d , t h e i m p o r t a n c e o f w a t e r n a v i g a t i o n i n t h e

s e t t l e m e n t o f t h e r e g i o n c a n n o t b e o v e r e m p h a s i z e d , and i t i s

n o t s u r p r i s i n g t h a t t h e e a r l y d e s c r i p t i o n s o f t h e a r e a

f o c u s e d a l o n g B ay o u s Teche and V e r m i l i o n . The f a c t t h a t

e a r l y n a v i g a t i o n a l o n g t h e s e s t r e a m s vvus n o t i d e a l i s p o i n t e d

22 S u r v e y o r ' s p l a t e s , s u r v e y e d a b o u t 1800 and now on f i l e a t t h e l o u i s i a n a S t a t e U n i v e r s i t y D epartm en t o f A r c h i v e s and M a n u s c r i p t s , o f t h e p r e s e n t A r n a u d v i l l e r e g i o n show th e w i d t h o f Bayou Teche a s 175 f e e t . A maximum e s t i m a t e o f i t s w i d t h t o d a y i s a p p r o x i m a t e l y 125 f e e t . Bayou F u s i l i e r i s shown a s a p p r o x i m a t e l y 130 f e e t i n w i d t h , i n d i c a t e d i t was f u n c t i o n i n g a s a d i s t r i b u t a r y o f t h e T e c h e , a p o s i t i o n i t f u l f i l l s t o d a y o n l y d u r i n g e x t r e m e f l o o d s .

124

o u t by S i b l e y ( 1 8 0 3 , p . 50 ) who s t a t e s :

There i s l i k e w i s e a s m a l l c o a s t i n g t r a d e b e tw e e n t h e A t a c a p a s and O p e l o u s a s , and New O r l e a n s , by way o f t h e B a l i z e , w h ic h w ould i n c r e a s e , i f t h e r e was any e n c o u r a g e m ent g i v e n by th e g o v e r n m e n t , t o c l e a r away a f e w o b s t r u c t i o n s , c h i e f l y c a u s e d by f a l l e n t i m b e r , i n t h e s m a l l r i v e r s and c r e e k s l e a d i n g t o them .

L a t e r works by Robin ( 1 8 0 7 ) , Darby ( 1 8 1 8 ) , C a t h c a r t

( 1 8 1 9 ) , F l i n t ( 1 8 3 2 ) , Duncan ( 1 8 5 0 ) , B r e n t and H e b e r t ( 1 8 5 6 ) ,

H i l g a r d (1 8 7 3 and 1 8 8 4 ) , Hoffman ( 1 8 8 1 ) , C o l l i n s ( 1 8 8 1 ) ,

P e r r i n ( 1 8 9 1 ) , Quinn ( 1 8 9 6 ) , L i p s e y ( 1 9 1 8 ) , C l i n e ( 1 9 2 7 ) ,

combined w i t h t h e r e c e n t R e p o r t s o f t h e C h i e f o f e n g i n e e r s ,

U. S . Army, a l l o w s a f a i r l y c o m p le t e p i c t u r e t o be drawn o f

t h e Bayou Teche and V e r m i l i o n h i s t o r y , d u r i n g t h e l a s t 150

y e a r s . Such a r e v i e w o f t h e l i t e r a t u r e g i v e s r i s e t o t h e

f o l l o w i n g o b s e r v a t i o n s : ( 1 ) Bayou Teche i s b u t t h e s p e c t r e

o f a f o r m e r , g r e a t e r s t r e a m ; ( 2 ) were i t n o t f o r man’ s i n

t e r v e n t i o n , t h e p r e s e n t c h a n n e l o f Bayou Teche w ou ld be i n

an ad v a n ce d s t a t e o f d e t e r i o r a t i o n ; ( 3 ) two d i s t i n c t s e t s o f

n a t u r a l l e v e e s f l a n k Bayou T ech e; and ( 4 ) th e V e r m i l io n

R i v e r f u n c t i o n e d a s a d i s t r i b u t a r y o f Bayou Teche u n t i l

f a i r l y r e c e n t t i m e , and s t i l l s e r v e s i n t h i s c a p a c i t y a t e x

treme f l o o d s t a g e .

R e c e n t g e o l o g i c i n v e s t i g a t i o n s have t e n d e d t o c o n f ir m

the a b o v e m e n t io n e d o b s e r v a t i o n s , ilowe and M o r e s i (1 9 3 1 and

1 9 3 3 , P* 31) s t a t e :

At t h e p r e s e n t t i m e Bayou Teche i s a c o m p a r a t i v e l y s m a l l s t r e a m im p r i s o n e d b e tw e e n g i g a n t i c n a t u r a l l e v e e s .

125

We have a l r e a d y n o t e d t h a t t h e s e l e v e e s a r e com parab le i n s i z e t o t h o s e o f t h e p r e s e n t day M i s s i s s i p p i R i v e r . I t a p p e a r s e v i d e n t t h a t a s tr ea m t h e s i z e o f t h e p r e s e n t Bayou Teche c o u l d n o t have formed su ch l e v e e s . Kor d o e s i t appear p o s s i b l e t h a t t h e y c o u ld have been formed by t h e Red R i v e r f o r t h e y a r e composed o f m a t e r i a l q u i t e d i s t i n c t from t h a t c a r r i e d by t h e Red R i v e r . I t i s now r e a s o n a b l y w e l l known t h a t t h e c o u r s e o f Bayou Teche was o c c u p i e d by Red R i v e r w i t h i n t h e p a s t th ou sa n d y e a r s .The r e c o r d o f t h i s o c c u p a t i o n a p p e a r s i n t h e narrow s t r i p o f t y p i c a l Red R i v e r s e d i m e n t w h ich f l a n k s Bayou Teche w i t h i n t h e l e v e e s t h e m s e l v e s . That Red R iv e r was a much s m a l l e r s tr ea m th a n t h e one w hich formed t h e g r e a t l e v e e s f l a n k i n g Bayou Teche i s c l e a r l y shown by t h e f a c t t h a t t h e Red R i v e r s e d i m e n t d o e s n o t r e a c h t o t h e t o p o f th e l e v e e s and i s n o t foun d on th e o u t s i d e o f th e l e v e e s e x c e p t where d i s t r i b u t a r i e s su ch a s C a ta h o u la C o u lee o r Bayou F u s e l i e r o c c u r . The sudden a p p ea r a n c e o f th e g r e a t l e v e e s o f Bayou Teche r i s i n g o u t o f t h e swamps o f th e d e l t a in S t . Landry P a r i s h show t h a t t h e y a re but rem nan ts o f a much more e x t e n s i v e n a t u r a l l e v e e s y s t e m .The p r e s e n t Bayou Teche may bo c o n s i d e r e d a s o r t o f r e l i c t s t r e a m . . .

R u s s e l l ( 1 9 3 9 , P» 1208) c o n c l u d e s :

. . . Prom meander p a t t e r n s i t i s e a s y t o i d e n t i f y t h e c o u r s e f o l l o w e d by Eayous Wauksha, O o u r t a b le a u , and Teche a s an abandoned M i s s i s s i p p i R i v e r c h a n n e l . I t i s a l s o a p p a r e n t t h a t t h e c o u r s e f o l l o w e d by Bayous B o u e f , C o u r t a b lo a u , Carron, and M a r ie c r o q u a n t b e l o n g s t o a n o t h e r s t r e a m . That t h i s s t r e a m i s Red R i v e r may be d e m o n s t r a t e d r e a d i l y by t r a c i n g Bayou B oeuf c o n t i n u o u s l y upstream t o the v i c i n i t y o f A l e x a n d r i a , where i t j o i n s t h e e x i s t i n g Red R i v e r c h a n n e l . In t h e f i e l d , t h e cont r a s t i s s t r i k i n g b e tw e en th e g r a y s e d i m e n t s o f t h e o l d M i s s i s s i p p i l e v e e s and t h e b r i g h t r e d l e v e e s o f t h e Red. The l i n e o f Red R i v e r l e v e e s e x t e n d i n g down Bayou Boeuf may be t r a c e d w i t h o u t i n t e r r u p t i o n t o a p o s i t i o n be tw een M i s s i s s i p p i l e v e e s a l o n g Bayou T e ch e . . .

F i s k (1 9 4 4 ) o p i n e s t h a t t h e Teche segm ent was f i r s t

o c c u p i e d by t h e M i s s i s s i p p i R i v e r f o l l o w i n g 0 t im e ( s e e F i g .

18b) and t h a t t h e p i l o t c h a n n e l o f t h i s new ly d i v e r t e d

M i s s i s s i p p i was p r o b a b ly t h e c h a n n e l o f the combined Red and

A rka n sas r i v e r , w h ic h were f l o w i n g t o t h e G u l f i n i n d e p e n d e n t

126

c o u r s e s a l o n g t h e w e s t e r n v a l l e y w a l l . F i s k ( 1 9 4 4 ) a l s o

" b e l i e v e s t h a t d u r i n g s t a g e 4 th e M i s s i s s i p p i abandoned th e

Teche c h a n n e l l e a v i n g t h e combined Red and A r k a n sa s i n o c

c u p a n c y . The A r k a n sa s soo n l e f t t h e T eche and r e j o i n e d the

M i s s i s s i p p i , and by s t a g e s e v e n t h e Red no l o n g e r f l o w e d

w i t h i n th e T e c h e - M i s s i s s i p p i c o u r s e .

F i e l d e v i d e n c e s u p p o r t s t h e ab ov e m e n t io n e d h y p o t h e

s i s . F ig u r e 19a shows t h e r e l a t i o n s h i p o f th e T e c h e -

l v i i s s i s s i p p i and Red l e v e e s t o t h e P r a i r i e s u r f a c e . R ote

t h a t t h e two s e t s o f l e v e e s a r e r e a d i l y d i s c e r n i b l e . Fur

t h e r m o r e , a t some l o c a t i o n s a t h i r d s e t o f narrow l e v e e s ,

t h o s e o f t h e p r e s e n t Bayou T e c h e , can be foun d i n s i d e t h e

Red R i v e r l e v e e s f l a n k i n g t h e p r e s e n t s t r e a m . The c u l t u r a l

e v i d e n c e p r e s e n t e d by L l c l n t l r e ( 1 9 5 4 , p . 7 7 ) i n d i c a t e s t i ia t

t h e T e c h e - M i s s i s s i p p i c o u r s e was abandoned by t h e r i v e r

p r i o r to M a r k s v i l l e t im e and t h a t t h e Red o c c u p i e d t h e Teche

c o u r s e d u r in g t h e M a r k s v i l l e p e r i o d . These d a t a a g r e e w i t h

F i s k ’ s i n t e r p r e t a t i o n ( F i g . 1 8 b ) .

B o r i n g s i n t h e a r e a b e tw een t h e T e c h e - M i s s i s s i p p i and

Red l e v e e s f l a n k i n g Bayou Teche s u g g e s t t h a t t h e abandonment

o f t h e Teche c o u r s e by t h e r i v e r was a r e l a t i v e l y s l o w p r o

c e s s a s t h e r e i s no a b r u p t change i n s e d im e n t c o l o r , but

r a t h e r a g r a d u a l t r a n s i t i o n t o t h e a l m o s t pure r e d c o l o r a

t i o n o f t h e Red l e v e e s .

F i e l d e v i d e n c e a l s o s u p p o r t s t h e p r e m is e t h a t t h e

V e r m i l io n R i v e r f u n c t i o n e d a s a d i s t r i b u t a r y o f t h e T e ch e -

Red, i n f a c t , o f t h e T e c h e - M i s s i s s i j . p i . From L a f a y e t t e a l

m ost to V e r m i l io n Bay t h e V e r m i l io n R i v e r f o l l o w s th e aban

doned c h a n n e l o f a P l e i s t o c e n e M i s s i s s i p p i R iv e r ( F i g . 1 6 ) .

The p r e s e n c e o f t h i s c o n f i n i n g t r o u g h made i t p o s s i b l e f o r

the V e r m i l io n t o t r a v e r s e a band o f P r a i r i e up land a p p r o x i

m a t e l y t h i r t y m i l e s i n w i d t h and e x p l a i n s t h e a b s e n c e o f

w e l l d e v e lo p e d n a t u r a l l e v e e s a l o n g p o r t i o n s o f i t s c h a n n e l

so u t h o f L a f a y e t t e . From i t s j u n c t i o n w i t h Bayou Teche

( F i g . 25) th e s t r e a m t r a c e s a s e r p e n t i n e p a t h , c o n t r o l l e d

p r i m a r i l y by r e l i c t meander s c a r s o f e a r l y , T e c h e - M i s s i s s i p p i

c o u r s e s , u n t i l i t e n t e r s t h e l r a i r i e T e r r a c e a t L a f a y e t t e .

P o r t i o n s o f t h e s e e a r l y T e c h e - M i s s i s s i p p i c o u r s e s e r e e a s i l y

d i s c e r n i b l e on a e r i a l p h o t o g r a p h s . A few t r a c e s o f t h e Red-

A rka n sa s meander b e l t a r e a l s o d i s t i n g u i s h a b l e on a e r i a l

p h o to g ra p h s a s meander s c a r s , and c u s p a t e i n d e n t a t i o n s in

the P r a i r i e e s c a r p m e n t . These f e a t u r e s a r e o f a s i z e n o t

comparable w i t h s i m i l a r form s a s s o c i a t e d w i t h t h e T ech e-

M i s s i s s i p p i .

F i s k ( 1 9 4 4 , P l a t e 15) i n d i c u t e s t h a t Bayou V e r m i l io n

f u n c t i o n e d as a s t a g e 3 d i s t r i b u t a r y o f t h e T e c h e - M i s s i s

s i p p i . F u r th erm o re , i n t h e t e x t F i s k ( 1 9 4 4 , p . 42) ob

s e r v e s , "The V e r m i l io n R iv e r a t L a f a y e t t e , L a . , p r o b a b ly

s e r v e d a s a d i s t r i b u t a r y o f t h e M i s s i s s i p p i f o r t h e f i r s t

t im e d u r i n g t h i s s t a g e ( S t a g e 1 ) . " R e c o n n a i s s a n c e f i e l d

128

work, p l u s c a r e f u l e x a m i n a t io n o f a e r i a l p h o t o g r a p h s , o f th e

complex r e g i o n be tw een L a f a y e t t e and A r n a u d v i l l e e n a b l e s th e

p r e s e n t w r i t e r t o c o r r o b o r a t e , t o some e x t e n t , F i s k ' s v i e w s

and p r e s e n t a more d e t a i l e d p i c t u r e o f t h e e v o l u t i o n o f th e

Upper V e r m i l io n R i v e r .

In a l l p r o b a b i l i t j r l o c a l r a i n f a l l d r a i n a g e m a i n t a i n e d

a s t r e a m w i t h i n t h e g u l fw a r d p o r t i o n o f t h e P l e i s t o c e n e

meander s c a r s , s o u t h w e s t o f L a f a y e t t e ( F i g s . 2 and 1 6 ) , l o n g

b e f o r e t h e T e c h e - M i s s i s s i p p i f lo w e d i n t o t h e L a f a y e t t e -

A r n a u d v i l l e r e g i o n . S l i g h t headward e r o s i o n by t h i s s tr ea m

p r o b a b ly to o k p l a c e ; how ever , i t d id n o t , s u b s e q u e n t l y , t a p

th e T e c h e - M i 3 s i s s i p p i d r a i n a g e s y s t e m t h r o u g h t h i s p r o c e s s

a l o n e . C r e v a s s i n g o f t h e T e c h e - M i s s i s s i p p i l e v e e s was a l s o

n e c e s s a r y . T h is c r e v a s s i n g p o s s i b l y o c c u r r e d d u r in g S t a g e 23A ( F i g . 2 5 ) , b u t more p r o b a b ly d u r in g S t a g e B, t h u s g i v i n g

r i s e t o th e a n c e s t r a l V e r m i l io n R i v e r whose c o u r se i s i n d i

c a t e d by t h e d a sh e d l i n e . The upper c o u r s e o f t h e p r e s e n t

Bayou V e r m i l i o n , between Bayou F u s i l i e r and L a f a y e t t e ,

e x i s t e d a s a backswamp t r i b u t a r y s trea m d u r i n g S t a g e B. The

upper p o r t i o n o f Bayou V e r m i l io n f i r s t r e c e i v e d f l o w from

s t a g e s A and C d e p i c t e d i n F ig u r e 25 do n o t c o r r e sp o n d e x a c t l y t o F i s k ' s S t a g e s 1 and 2 a s shown on P l a t e 1 5 , S h e e t 4 ( F i s k , 1 9 4 4 ) , t h e r e f o r e , F i s k ' s t e r m i n o l o g y was n o t u s e d . L e v e r t h e l e s s , i n a g e n e r a l s e n s e S t a g e s A, B, and C may be c o n s i d e r e d t o a p p r o x im a te S t a g e s 1 , 2 , and 3 o f F i s k ' s c h r o n o l o g y .

BAYOU VERMILION

BAYOU TECHEBAYOU

T O R T U E r BAYOU C A PU C IN

\L A K E N >■ L A

P O IN T E

EVOLUTION OF THE UPPER VERMILIONRIVER (SEE TE X T PAGE 128 )

_ S 'V

E a r l y C o u r s e o f T e c h e - M i s s i s s i p p i

L a t e r C o u r s e o f T e c h e - M i s s i s s i p p i

Di s t r i b u t a r y & b a c k s w a m p d r a i n a g e D u r i n g t h i s s t a g e

C L a s t C o u r s e O c c u p i e d b y t h e T e c h e - M i s s i s s i p p i>»"•# . • • • d i s t r i b u t a r y & b a c k s w a m p d r a i n a g e

* • * d u r in g t h i s s t a g e

DRAINAGE OF THIS STAGE STILL IN EXISTENCE AT THE PRESEN T TIME

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129

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S C A L E IN MILES 5 O S 10 IS 2 0L O C A TIO N MAP

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130

th e T e c h e - M i s s i s s i p p i d u r i n g S tu g e C. D u r in g t h i s s t a g e a

c r e v a s s e o c c u r r e d i n th e T e o h e - M i s s i s s i p p i l e v e e s n e a r t h e

p r e s e n t T e c h e - F u s i l i e r j u n c t i o n , p o u r i n g w a t e r i n t o an

e a r l i e r ( S t a g e A) T e c h e - M i s s i s s i p p i meander s c a r ( F i g . 2 5 ) .

However , th e w a t e r s b r e a c h e d t h e c o n f i n e s o f t h e o l d s c a r

and merged w i t h t h e backswamp d r a i n a g e s y s t e m , t h u s e n a b l i n g

a t y p i c a l s h o r t - l i v e d c r e v a s s e c h a n n e l t o d e v e l o p i n t o a

more permanent d i s t r i b u t a r y s t r e a m .

I t i s i n t e r e s t i n g t o n o t e t h a t t h e l e v e e s a l o n g Bayou

F u s i l i e r , n e a r i t s j u n c t i o n v / i th t h e T e ch e , a r e o f t h e same

h e i g h t a s t h o s e o f t h e T e c h e - J . I i s s i s s i p p i , th u s making i t

o b v i o u s t h u t , e v e n though m ost o f th e l e v e e m a t e r i a l found

a l o n g t h e V e r m i l i o n i s r e d d i s h i n c o l o r , t h e V e r m i l io n was

formed p r e v i o u s t o t h e abandonment o f t h e Teche c o u r s e by

t h e M i s s i s s i p p i . Thus , t h e V e r m i l io n has f u n c t i o n e d a s a

d i s t r i b u t a r y o f th e T e c l i e - M i s s i s s i p p i , T e ch e -R e d , a nd , u n t i l

l e s s th a n 200 y e a r s a g o , Bayou T e c h e . C o n s e q u e n t l y , t h e

s e d im e n t l o a d c a r r i e d by t h i s s t r e a m h a s been s u b j e c t t o

g r e a t v a r i a t i o n s d u r i n g i t s v e r y e a r l y h i s t o r y , a p o i n t t h a t

s h o u ld be born e i n mind when d i s c u s s i n g s e d i m e n t a t i o n n e a r

i t s form er mouth (S ee s e c t i o n on s h o r e l i n e c h a n g e s and

c h e n i e r s ) .

T r a c i n g t h e fo rm e r c h a n n e l s o u t h o f th e p r e s e n t mouth

i s n o t an e a s y t a s k . As p r e v i o u s l y m e n t i o n e d , t h r o u g h o u t i t s

c e n t r a l s e c t i o n t h e r i v e r i s c o n t r o l l e d by a P l e i s t o c e n e

131

M i s s i s s i p p i meander p a t t e r n ( F i g . 1 6 ) . An e f f o r t , t h e r e f o r e ,

was made t o t r a c e t h i s meander p a t t e r n southw ard from th e

p o i n t where i t d i s a p p e r a s b e n e a t h t h e R e c e n t s e d i m e n t s .

A c c u r a t e c o n t o u r i n g o f t h e h i g h l y i r r e g u l a r , b u r i e d P l e i s t o

c en e s u r f a c e w i t h a U n i t e d number o f b o r i n g s i s a l m o s t im-.

p o s s i b l e . N e v e r t h e l e s s , a f t e r p l o t t i n g o v e r 10U b o r e h o l e s ,

from v a r i o u s s o u r c e s , and c a r e f u l l y s t u d y i n g a e r i a l p h o t o

g r a p h s o f t h e r e g i o n , an a t t e m p t was made t o c o n t o u r t h e

m a r s h - v e n e e r e d P l e i s t o c e n e s u r f a c e and t o e s t a b l i s h th e

s o u t h e r n e x t e n t i o n o f t h e V e r m i l io n c h a n n e l ( F i g . 2 6 ) . ^ 4

The d a t a i n d i c a t e t h u t th e V e r m i l io n R i v e r l e a v e s t h e

P l e i s t o c e n e meander b e l t i n t h e v i c i n i t y o f t h e I n t r a c o a s t a l

Canal and f o l l o w s a more s o u t h w e s t e r l y c o u r s e ( F i g . 1 6 ) ,

The t r o u g h i n th e P l e i s t o c e n e s u r f a c e ( F i g . 2 6 ) , a l o n g t h i s

form er c o u r s e , was u n d o u b te d ly formed i n p a r t by V e r m i l io n

R i v e r s c o u r . However , a d e p r e s s i o n o f some s o r t , which

c o n t r o l l e d t h e c o u r s e o f th e s t r e a m , was probabljr i n e x i s

t e n c e p r e v i o u s l y .

The s o u t h e r n c o n t i n u a t i o n o f t h e V e r m i l io n R iv e r

( P l a t e I , F i g . c and F i g . 26) h a s been e s t a b l i s h e d on t h e

24 The c o n t o u r s shown in t h i s f i g u r e a r e , i n many c a s e s , open t o q u e s t i o n ; how ever , t h e f i g u r e i s b a s e d on more i n f o r m a t i o n than any o t h e r p r e v i o u s l y p u b l i s h e d c o n t o u r map o f the a r e a . The e x i s t e n c e o f t h e NE-Sl/ t r e n d i n g t r o u g h , b e tween V e r m i l i o n Bay and B e l l e I s l e , seem s d e f i n i t e l y e s t a b l i s h e d . The p r o l o n g a t i o n o f t h i s t r o u g h t o t h e s o u t h w e s t i s v e r y c o n j e c t u r a l . Bore h o l e s put down by Edward Orton n e a r t h e .m o u t h o f R o l l o v e r Bayou, i n Cameron P a r i s h , i n d i c a t e a F l e i s t o c e n e v a l l e y w h ic h c o u l d p o s s i b l y be t h e c o n t i n u a t i o n o f t h i s t r o u g h .

SUBSURFACE CONTOUR MAPTOP OF PLEISTOCENE

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Figure 2 6

b a s i s o f s e v e r a l f a c t o r s . B ir d I s l a n d , w h ic h was c o m p l e t e l y

removed by d r e d g i n g a b o u t t e n y e a r s a g o , f o r m e r l y was

l o c a t e d a b o u t o n e - h a l f m i l e o f f t h e p r e s e n t mouth o f t h e

r i v e r in V e r m i l i o n B ay . T h i s i s l a n d , w h ich was o r i g i n a l l y a

h ig h a r e a s i t u a t e d on the l e f t bank o f t h e r i v e r , c o n s i s t e d

o f midden m a t e r i a l ( p r i m a r i l y s h e l l ) i n w h ich much I n d i a n

p o t t e r y w as f o u n d . C l o s e l y sp a c e d b o r e h o l e s a l o n g t h e e x

t e n s i o n o f l a n d , l e a d i n g t o Mud P o i n t ( F i g . 2 6 ) , o p p o s i t e

th e mouth o f t h e r i v e r r e v e a l t h a t th e c h a n n e l d id n o t e x

t en d s o u t h e a s t w a r d In to t h i s r e g i o n . To t h e s o u t h i t i s

n o t e d t h a t t h e B e l l e I s l e B a y o u - B e l l e I s l e Lake-One M i l e

Bayou p a t t e r n i s c e r t a i n l y n o t t y p i c a l o f m arsh lun d d r a i n a g e

( F i g . 2 ) , b u t r a t h e r i s more c l o s e l y a l l i e d t o t h a t o f t h e

V e r m i l i o n R i v e r . In a d d i t i o n , bore h o l e s i n d i c a t e t h e p r e

s e n c e o f a t r o u g h c u t i n t h e P l e i s t o c e n e s u r f a c e . t r e n d i n g

S’.7 from t h e n o r t h e r n e n t r a n c e t o Fearman Lake. H e n c e , i t

seem s r e a s o n a b l e t o assume t h a t th e V e r m i l i o n f o l l o w e d t h i s

t r e n d t o t h e IdV/ c o r n e r o f B e l l e I s l e .

At t h e t im e o f t h e f i r s t T e c h e - I a i s s i s s i p p i f l o w down

t h e V e r m i l io n t h e s h o r e l i n e p r o b a b ly p a r a l l e l e d t h e Back

R i d g e - B e l l e I s l e - C l i e n i e r au T ig r e t r e n d t o t h e n o r t h and

n o r t h e a s t ( P l a t e I , F i g . c ) . The s t r e a m e r r a t i c a l l y p r o

graded a c r o s s th e s h a l l o w embayment, bounded by t h e above

m e n t io n e d s h o r e l i n e , and p o s s i b l e t r a c e s o f i t s c h a n n e l can

be foun d on a e r i a l p h o t o g r a p h s r u n n in g t o t h e w e s t o f B e l l e

134

I s l e . S ed im e n t d i s c h a r g e i n t h i s a r e a p r o b a b l y p r o v i d e d th e

m a t e r i a l t h a t s u b s e q u e n t l y , th r o u g h s h o r e l i n e r e t r e a t , formed

B e l l e I s l e . ( S h o r e l i n e c h a n g e s a r e d i s c u s s e d i n t h e f o l l o w

i n g s e c t i o n . )

However, t h e V e r m i l i o n 3 { i v e r , s o u t h o f A b b e v i l l e ,

n e v e r c a r r i e d a l a r g e p e r c e n t a g e o f T e c h e - l d i s s i s s i p p i f l o w .

E v i d e n c e o f t h i s f a c t i s o b v i o u s from t h e a b s e n c e o f v / e l l

d e v e l o p e d l e v e e s n ea r t h e p r e s e n t mouth o f t h e s t r e a m , and

th e l a c k o f any e x t e n s i v e d e l t a nea r i t s o r i g i n a l d i s t a l

end ( B e l l e I s l e r o g i o n - - P l n t e I , F i g s . c and d ) . There i s a

d e f i n i t e p o s s i b i l i t y t h a t t h e g r e a t e s t p o r t i o n o f t h e V er

m i l i o n f l o w f o l l o w e d t h e o t h e r s e t o f P l e i s t o c e n e M i s s i s

s i p p i meander s c a r s (1 - lu te I , F i g . c and F i g . 1 6 ) , s o u t h -

w estw ard from A b b e v i l l e . The m eanders a r e t r u n c a t e d by t h e

n o r t h e a s t e r n s h o r e l i n e o f 'white Lake; h o w e v e r , th e t r e n d ,

now marsh c o v e r e d , p r o b a b l y c o n t i n u e s t o t h e s o u t h w e s t o f

th e l a k e . The a l i g n m e n t o f t h e c h o n i e r s , s o u t h e a s t and w e s t

o f V'hite Lake ( F i g . 1 6 ) , i n d i c a t e s t h a t d u r in g t h e t im e o f

t h e i r f o r m a t i o n a "V" shaped e x t e n s i o n o f l a n d p r o t r u d e d

i n t o t h e O-ulf from t h e s o u t h w e s t c o r n e r o f t h e p r e s e n t l a k e .

T h is e x t e n s i o n was d e s t r o y e d d u r i n g t h e p e r io d o f s h o r e l i n e

r e t r e a t w h ich r e s u l t e d in t h e f o r m a t i o n o f i-ecan I s l a n d

( F r o n t R i d g e ) ( F i g . 2 ) . A l th o u g h th e w r i t e r h a s c o m p le te d

v e r y l i t t l e f i e l d -work i n t h i s a r e a , he f e e l s t h a t p h y s i o

g r a p h i c e v i d e n c e s u g g e s t s t h e e x i s t e n c e o f a f a i r l y im p o r t a n t

s t r e a m , f l o w i n g southwestwarcl from t h e g e n e r a l v i c i n i t y o f

A b b e v i l l e t o th e C u l f , d u r in g a p o r t i o n o f t h e e a r l y Ver

m i l i o n h i s t o r y ( P i u t e I , F i g . c ) .

As p r e v i o u s l y m en t ioned Bayous Cypremort and Sale*

a l s o f u n c t i o n e d a s d i s t r i b u t a r i e s o f the T e c h e - A i i s s i s s i p p i .

’.7hen th e combined Red-Arkansas R iv e r f i r s t f lo w e d i n t o the

a r e a , p a r a l l e l i n g thu w e s t e r n w a l l o f the e x i s t i n g l i i s s i s -25s i p p i A l l u v i a l V a l l e y , i t s pa th was barred by the p r e v i

o u s l y formed l o v e e r i d g e s o f Cyi.rex.iort and S a l e ' . A lthough

Bayou Cypremort was a r e l a t i v e l y minor s t r e a m , i t s l e v e e s ,

formed su b seq u e n t t o t h o s e o f B a le ' and th u s l e s s a f f e c t e d

by s u b s i d e n c e , p r o b a b ly formed th e main o b s t a c l e t o Red-

Arkansas f l o w . V/ator v;ns inpounued t o the n o r t h w e s t o f t h i s

r i d g e and s u b s e q u e n t l y breached i t w i t h i n a s h o r t p e r io d o f

t i m e . The e x i s t i n g w e s t e r n v a l l e y w a l l had a f u n n e l i n g e f

f e c t on t h e d r a in a g e o f th e r e g i o n and t h u s a i d e d , by con

c e n t r a t i n g water near tlie' i n t e r s e c t i o n o f i t s t r e n d w i t h th e

Cypremort l e v e e s , the b r e a c h in g p r o c e s s . The s l i g h t l y d e

t e r i o r a t e d c h a n n e l o f Bayou Cypremort was un dou bted ly o c c u

p ie d by a d i s t r i b u t a r y s tream a t t h i s t i m e , V/hon the

The v a l l e y "w all" a t t h i s t ime ( H a t e X, F i g s . a and b) c o n s i s t e d o f a s e r i e s o f P r a i r i e T errace promont o r i e s p r o j e c t i n g i n t o t h e "sea" o f R ecent a l lu v i u m . The embayments, f l a n k i n g t h e p r o m o n t o r i e s , r e p r e s e n t e d the headv/ard p o r t i o n s o f t h e t r o u g h s w hich were c r e a t e d d u r in g t h e l a t e , / i s c o n s i n g l a c i a t i o n ( F i g . 1 5 a ) , when s e a l e v e l was low ered by a p p r o x im a t e ly 400 f e e t .

136

r u p tu r e was com pleted t h e s tr ea m c o n t in u e d so u th e a s tw a r d

s t i l l f l a n k i n g th e w e s te rn v a l l e y ’.v a i l , w h ich , i n t h i s s e c

t i o n , had v e r y l i t t l e s u r f i c i a l e x p r e s s i o n . The o l d e r , more

s u b s id e d n a t u r a l l e v e e r i d g e o f t h e Bayou S a l e ' sy s tem p r e

s e n t e d a l e s s e r o b s t a c l e than t h a t o f Bayou Cypremort.

B r ea c h in g r a p i d l y o c c u r r e d and th e y o u n g e s t ( l e a s t d e t e r i o r

a t e d ) c h a n n e l o f t h e Bayou S a l e 1 sy s te m ( P l a t e I , F i g . a ,

c o u rse 3) was o c c u p i e d , i n p a r t , by a d i s t r i b u t a r y s t r e a m .

S u b s e q u e n t ly t h e M i s s i s s i p p i d i v e r t e d i n t o the a r e a ;

o c c u p y in g t h e Red-Arkansas c o u r se and, through l a t e r a l

p l a n a t i o n , fo rm in g th e p r e s e n t w e s te r n w a l l o f t h e M i s s i s

s i p p i A l l u v i a l V a l l e y . Bayou Cypremort s e r v e d a s a d i s

t r i b u t a r y f o r a s h o r t t i m e , however, a s t h e a n g l e o f d i v e r

g e n c e from the main s tr ea m was a lm o s t 9 0 ° , i t was r a p i d l y

s e a l e d o f f . The S a l e ’ d i s t r i b u t a r y d i v e r g e d a t a more

f a v o r a b l e a n g l e and i t i s o b v io u s from t h e a c c r e t i o n p a t t e r n

found in t h e r e g i o n ( F i g . 21) t h a t t h e s t r e a m , a l t h o u g h

s e a l e d o f f b e f o r e t h e Red R iv e r o c c u p ie d th e Teche c o u r s e , ^

R u s s e l l ( 1 9 3 o , pp. 95-V7 and 103) has shown th e v a l i d i t y o f t h e c o n c e p t t h a t l a r g e a n g l e s o f d i v e r s i o n r e s u l t in r a p id s e a l i n g o f f o f a d i s t r i b u t a r y ; w h er ea s , low a n g l e d i v e r s i o n c h a n n e l s t e n d to be m a in t a in e d .

S e v e r a l bore h o l e s put down a t v a r io u s p l a c e s a lo n g Bayou S a l e ' and Cypremort f a i l e d t o r e v e a l any red s e d im e n t , t h u s s u g g e s t i n g t h a t by th e t im e t h e Teche c hann el was o c c u p ie d by t h e Red t h e s e s tr e a m s were n o t r e c e i v i n g u n i n t e r r u p t e d f l o w . Y.'ith t h e e x c e p t i o n o f th e V e r m i l io n R i v e r , t h i s s t a t e m e n t can be a p p l i e d to a l l t h e T e c h e - M i s s i s s i p p i shown on P l a t e I ( F i g . c ) .

137

r e c e i v e d f l o w f o r a c o n s i d e r a b l e l e n g t h o f t i m e .

Otlier d i s t r i b u t a r i e s ( P l a t e I , F i g . c ) o f t h e T e c h e -

M i s 3 i s s i p p i a r e foun d i n t h e r e g i o n . The c o u r s e r u n n i n g due

s o u t h from New I b e r i a was r e c o g n i z e d , on t h e b a s i s o f s o i l

t y p e s , by Mann and K olbe ( 1 9 12) and l a t e r m e n t io n e d by Howe

and M o r e s i ( 1 9 3 1 ) . B o r i n g s a l o n g t h e I n t r a c o a s t a l C an a l a t

p o i n t s s e e m i n g l y on t h e t r e n d o f th e d i s t r i b u t a r y , a s d e t e r

mined by an e x a m i n a t io n o f a e r i a l p h o t o g r a p h s , f a i l e d t o

e n c o u n t e r l e v e e m a t e r i a l . However , t h e b o r i n g s a r e r e l a

t i v e l y w i d e l y sp a c e d and t h e v / r i t e r c a n n o t i r r e v o c a b l y s t a t e

t h a t a s t r e a m o f some m a g n i tu d e d i d n o t f l o w th r o u g h t h i s

r e g i o n . The c o u r s e t r e n d i n g s o u t h from F r a n k l i n ( P l a t e I ,

F i g . c ) i s t h e remnant o f a f a i r l y l a r g e d i s t r i b u t a r y a s

i n d i c a t e d by t h e s i z e o f the l e v e e r i d g e .

In c o n c l u s i o n , th e d a t a p r e s e n t e d on t h e p r e c e d i n g

p a g e s s u g g e s t t h e f o l l o w i n g p o s t S a l e ' -C yprem ort s e q u e n c e o f

e v e n t s . S u b s e q u e n t t o r e d u c t i o n in f l o w , c a u se d by a r e

d i r e c t i n g o f M i s s i s s i p p i f l o w t o t h e e a s t w a r d , and p a r t i a l

d e t e r i o r a t i o n o f t h e S a l e ' , and, t o a l e s s e r e x t e n t , C y p re -

raort c h a n n e l s , t h e combined A r k a n sa s and Hed K i v e r s d i v e r t e d

i n t o t h i s a r e a a l o n g t h e e x i s t i n g w e s t e r n w a l l o f t h e M is

s i s s i p p i A l l u v i a l V a l l e y . At t h i s p o i n t Sa le* and Cypremort

p r o b a b l y f u n c t i o n e d a s t i d a l s t r e a m s . The f u n n e l i n g e f f e c t

o f t h e v a l l e y w a l l a i d e d i n b r e a c h i n g th e l e v e e r i d g e s o f

Cypremort and S a l e ’ . The c h a n n e l s o f Cypremort and S a l e ’

were p r o b a b ly b o th o c c u p ie d by d i s t r i b u t a r y s t r e a m s a t t h i s

t i m e . L a te r th e M i s s i s s i p p i d i v e r t e d i n t o t h e r e g i o n and

o c c u p ie d t h e c h a n n e l p r e v i o u s l y e s t a b l i s h e d by t h e Red-

A r k a n sa s . The V e r m i l io n d i s t r i b u t a r y was c r e a t e d and Bayous

Cypremort and S a l e 1 s e r v e d in a s i m i l a r c a p a c i t y . Over

to p p in g o f t h e banks l e d t o t h e fo r m a t io n o f t h e s i z e a b l e

n a t u r a l l e v e e s which ure so a p p arent t o d a y . G r a d u a l ly , how

e v e r , the r i v e r wus d i v e r t e d from the Teche c o u r s e , l e a v i n g

th e Red, tra p p e d between o v e r s i z e d l e v e e s , i n p o s s e s s i o n o f

th e c h a n n e l c r e a t e d by t h e M i s s i s s i p p i . The Red R i v e r , in

t u r n , f l a n k e d i t s e l f w i th l e v e e s and s e n t a red f i n g e r o f

s i m i l a r m a t e r i a l gu l fw a r d a l o n g t h e V e r m i l io n . S u b s e q u e n t l y ,

the Red t o o r e l i n q u i s h e d t h e c h a n n e l and today t h e humble

Bayou Teche f l o w s between t h e d ou b le s e t o f n a t u r a l l e v e e s ,

to t h e Lower A t o h a f a la y a R i v e r .

SHORELINE FLUCTUATIONS AND THEIR SIGNIFICANCE AS

INDICATED BY THE CHEKIEKS OF VERMILION PARISH

The a r c u a t e s e r i e s o f s t r a n d e d beach r i d g e s and

c h e n i e r s foun d in th e c o a s t a l m a rsh la n d s o f V e r m i l io n P a r i s h

r e c e i v e d l i t t l e m en t io n i n t h e e a r l y l i t e r a t u r e . However,

an a r t i c l e a p p e a r i n g i n De Bow's Review ( V o l . 8 , 1 8 5 0 , p .

9 5 ) d e s c r i b e s C h en ier au T ig r e a s ", . . a s t r i p o f h ig h

l a n d , between t h r e e o r f o u r m i l e s l o n g , and from one and a

h a l f a c r e t o t h r e e - q u a r t e r s o f a m i l e w id e , thrown up on th e

margin o f t h e G u l f o f M ex ic o ."

H i l g a r d ( 1 8 8 4 , p . 162) o b s e r v e s :

. . . C u l t i v a t e d t r a c t s a r e on Pecan I s l a n d , a s i n u o us r i d g e i n t h e m arsh, ab o u t s e v e n m i l e s from th e b e a c h . T h is i s d e n s e l y t im b e r e d w i th pecan t r e e s , and, b e s i d e s th e n u t s o f t h i s t r e e , h a s produced s e a - i s l a n d c o t t o n , a l s o c a n e , and t r o p i c a l f r u i t s in abundance , t h e s o i l b e i n g a r i c h b l a c k loam o f g r e a t d e p t h . . . P e t i t e C h en ie r e I s l a n d (C h e n ie r au T i g r e ) , on the c o a s t e a s t o f P ecan I s l a n d , i s s i m i l a r in i t s c h a r a c t e r and p r o d u c t i o n .

P e r r i n ( 1 8 9 1 , P« 247) makes t h i s comment on the c u l

t u r a l l e v e l a t t a i n e d by t h e r e s i d e n t s o f Pecan I s l a n d , " I t

i s i n h a b i t e d by h o g s , c a t t l e and p e o p l e , and i t i s s a i d t h a t

t h e l a t t e r know l i t t l e more than the a n im a ls w i th which t h e y

l i v e ."

The im portance o f th e f i r m , w e l l d r a i n e d , c h e n i e r s a s

h a b i t a t i o n s i t e s in th e marsh i s o b v i o u s . G e o l o g i c a l l y

s p e a k in g t h e c h e n i e r s a re equa Lly i m p o r t a n t . Their signif icance

139

140

i s a p t l y su m m a r ize d by R u s s e l l ( 1 9 3 5 , p . 54) who s t a t e s :

The c o a s t a l m a rsh e s o r i g i n a t e d d u r in g p e r i o d s when t h e M i s s i s s i p p i R i v e r d i s c h a r g e d w e s t o f i t s e x i s t i n g m outh. P e r i o d s o f e a s t w a r d d i s c h a r g e o c c u r r e d a t t i m e s and a l l o w e d t h e s h o r e t o r e t r e a t . B e a c h e s were formed under su c h c o n d i t i o n s . When westward d i s c h a r g e a g a i n o c c u r r e d t h e c o a s t a d v a n c e d i n t o t h e G u l f l e a v i n g t h e m ost r e c e n t beach s t r a n d e d i n l a n d , becom ing a c h e n i e r . S u b s i d e n c e , due to t h e i n c r e a s i n g w e i g h t o f t h e M i s s i s s i p p i D e l t a , o c c u r r e d t h r o u g h o u t t h e w h o le h i s t o r y o f marsh gro w th and i s s t i l l i n p r o g r e s s . The h i g h e s t c h e n i e r s and l e a s t f l o o d e d marsh a r e n e a r e s t t h e e x i s t i n g c o a s t f o r t h e r e a s o n t h a t t h e marsh t h e r e i s you n g e s t and h e r e s u f f e r e d l e a s t s u b m e r g e n c e .

C o n s e q u e n t l y , e a c h c h e n i e r marks a pe i’i o d o f c o a s t a l

r e t r e a t , b e tw e e n two p e r i o d s o f a d v a n c e . T h i s p r o c e s s i s

o p e r a t i v e to d a y a l o n g t h e c o a s t o f V e r m i l io n P a r i s ) : . Due t o

i n c r e a s i n g d i s c h a r g e and s e d i m e n t c a r r y i n g c a p a c i t y o f t h e

A t c h a f a l a y a R i v e r a g r o w in g a r e a o f a c t i v e s e d i m e n t a t i o n h a s

been e s t a b l i s h e d a p p r o x i m a t e l y 125 m i l e s w estw ard o f t h e p r e

s e n t M i s s i s s i p p i mouth . T h i s i n f l u x o f s e d im e n t has a c c e l e

r a t e d t h e f o r m a t i o n o f m u d f l a t s a l o n g t h e V e r m i l io n P a r i s h

c o a s t , s t r a n d i n g t h e p r e s e n t b e a c h e s , and t h u s c r e a t i n g new

c h e n i e r s .

A l t h o u g h t h e a b o v e m en t io n e d p r o c e s s a d e q u a t e l y e x

p l a i n s t h e m ajor c h e n i e r s y s t e m s , o t h e r more l o c a l c h a n g e s

in s e d i m e n t a t i o n u n d o u b te d ly were i m p o r t a n t i n fo r m in g t h e

s m a l l e r c h e n i e r g r o u p s . Ror e x a m p le , s t r a n d e d r i d g e s o c c u r

n e a r t h e mouths o f f o r m e r l y e s t u a r i n e s t r e a m s such a s t h e

C a l c a s i e u and S a b in e R i v e r s in Cameron P a r i s h . The a r r a n g e

ment o f t h e s e r i v e r mouth c h e n i e r s , d i v e r g e n t to w a r d t h e

r i v e r and c o n v e r g e n t a l o n g t h e c o u s t av/ay from t h e m outh ,

i n d i c a t e s t h a t t h e i r f o r m a t i o n was d e p e n d e n t upon f l u c t u a

t i o n s in l o c a l c o n d i t i o n s and n o t c o n t r o l l e d by s h i f t s o f

t h e M i s s i s s i p p i m outh . I t i s i n t e r e s t i n g t o n o t e t h a t s i m i

l a r r i v e r mouth c h e n i e r s found i n Surinam a p p a r e n t l y d i v e r g e

av/ay from t h e r i v e r mouth (B rouw er , 1 9 5 3 ) , t h u s r e s e m b l i n g

e x t r e m e l y l a r g e r i v e r mouth s p i t s . The d i f f e r e n c e con p r o b a

b l y be e x p l a i n e d by a more p o w e r f u l l o n g s h o r e c u r r e n t a l o n g

t h e Surinam c o a s t ; i n any e v e n t , f u r t h e r s t u d y w i l l r e s u l t

i n many i n t e r e s t i n g c o m p a r i s o n s b e t w e e n t h e c h e n i e r s o f

S o u t h w e s t L o u i s i a n a and Surinam .

L o c a l c o n d i t i o n s m o d i f y t h e shape o f t h e b e a c h e s and

h e n c e , t h e r e s u l t i n g c h e n i e r s . U s u a l l y t h e t y p i c a l c h e n i e r

e x h i b i t s a r e l a t i v e l y s t e e p g u l f w a r d s l o p e ana a g e n t l e

landward i n c l i n a t i o n ( F i g . 2 7 a , I - r o f i l e A ); l i k e w i s e , modern

b e a c h e s , open t o d i r e c t a t t a c k o f th e G u l f w a v e s , d i s p l a y

t h e same s l o p e r e l a t i o n s h i p s ( F i g . 2 7 a , P r o f i l e B ) . How

e v e r , s m a l l e r p r e s e n t - d a y b e a c h e s f l a n k i n g s h a l l o w embay-

m en ts p r o t e c t e d from d i r e c t wave a t t a c k by c o a s t a l c o n f i g u r a

t i o n or a f a v o r a b l e a r ra n g em en t o f o f f s h o r e r e e f s e x h i b i t

g e n t l e g u l f w a r d s l o p e s and r e l a t i v e l y s t e e p landward s l o p e s

( F i g . 2 ? a , P r o f i l e C ) . The c o n c e n t r i c a r ra n g em en t o f a

s e r i e s o f c h e n i e r s ( lJe c a n I s l a n d - B e l l e I s l e - C h e n i e r au

T i g r e ) fo u n d i n V e r m i l i o n P a r i s h ( F i g . 2) s u g g e s t s t h a t t h e y

were form ed f l a n k i n g a p r o t e c t e d embayment. I f t h i s i s

BEACH AND CHE

BORE HOLE PR O FILE O F F R O N T RIDGE SURVEYED AUGUST 16, 1951 BEA RIN G N

PR O F IL E O F BEACH RID G E S E A S T O F G R O S S E IS L E P O IN T SURV EY ED A P R IL 2 9 , 1 9 5 2 BEARING N 2 0 * E

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142

CHENIER PROFILES SEE FIG . 28 FOR LOCATiONS

PROFILE OF PRESENT BEACH SURVEYED MARCH 8 , 1952

AT CHENIER AU TIGRE BEARING N 2 6 * W

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i -Tv t a r s r i - i - i -:;;BORE HOLE PROFILE OF LONG ISLAND

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1 4 3

CHENIER AU TIGRE c1

A B C D - LOCATIONS OF PROFILES SHOWN ON FIG. 27 a

S C A L E IN MILES 5 0 5

Figure 28

144

t r u e , m ost o f th e c h e n i e r s o f t h i s s e r i e s s h o u l d e x h i b i t a

g e n t l y s l o p i n g g u l f w a r d s u r f a c e . ( T h i s g e n e r a l i z a t i o n a p

p l i e s o n l y t o t h e c o n c e n t r i c a l l y a r r a n g e d c h e n i e r s and e x

c l u d e s s u c h fo rm s a s F r o n t R id g e o f P ecan I s l a n d and t h e

E-W t r e n d i n g p o r t i o n o f C h en ie r au T i g r e . ) The e a s t e r n m o s t

r i d g e s o f b o t h C h en ie r a u T i g r e and F r o n t R id g e ( F i g . 2 7 a ,

P r o f i l e D) d i s p l a y g e n t l y s l o p i n g g u l f w a r d f a c e s and r e l a

t i v e l y s t e e p landward s l o p e s . B e l l e I s l e p r e s e n t s an a l m o s t

s y m m e t r i c a l c r o s s s e c t i o n , h a v i n g g e n t l e g u l f w a r d and l a n d

ward s l o p e s ( F i g . 2 7 b ) .

C h e n i e r s o f t h i s t y p e p r o b a b l y r e p r e s e n t m i n o r s h o r e

l i n e f l u c t u a t i o n s i n p r o t e c t e d o m bay in en t s ; w h e r e a s , t h e

s t e e p l y - g u l f w a r d - s l o p i n g v a r i e t y d e n o t e a m a j o r r e t r e a t o f

t he g u l f s h o r e l i n e . The a b o v e s t a t e m e n t i s , o f c o u r s e , a

g e n e r a l i z a t i o n ; h o w e v e r , i t s e em s t o be v a l i d i n t h i s p a r

t i c u l a r c o a s t a l a r e a and l e a d s t h e v / r i t e r t o b e l i e v e t h a t

o n l y two c h e n i e r t r e n d s ( F r o n t R id g e a nd t h e 4-1/ r i d g e o f

C h e n i e r a u T i g r e ) c a n b e d e f i n i t e l y c o r r e l a t e d w i t h s h i f t s

o f t h e a c t i v e d e l t a o f t h e M i s s i s s i p p i R i v e r .

F i g u r e 29a a n d b s u m m a r i s e s t h e e f f e c t s o f t h e r i v e r

s e q u e n c e s p r o p o s e d by M c l n t i r e (19i>4) and F i s k (1 9 4 4 ) on t h e

c o a s t l i n e o f V e r m i l i o n P a r i s h . The r e l a t i v e p o s i t i o n o f t h e

a c t i v e d e l t a w i t h r e s p e c t t o t h e 9 ^ c V; m e r i d i a n o f l o n g i t u d e

h a s b e e n n o t e d f o r e u c h r i v e r c o u r s e . Mos t o f t h e f o r m e r

d e l t a s f a l l , i n t h e i r e n t i r e t y , e i t h e r w e s t o r e a s t o f t h i s

EFFECT OF POSTULATED DELTAIC SHIFTS ON VERMILION PARISH SHORELINE

M A R S H F O R M A T I O N - S H O R E L I N E A D V A N C E

B E A C H F O R M A T I O N - S H O R E L I N E R E T R E A T

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E A S T

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M A R S H F O R M A T I O N D O M I N A N T - S H O R E L I N E A D V A N C E W I T H M IN O R F L U C T U A T I O N S

W E S T

W E S T G R A N D R IV E

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RIVER S E Q U E N C E C H A R T S SHOWING E F F E C T S O F P O S T U L A T E DCOURSE CHRONOLOGY FOR PARTS A

145

JT DISCHARGE AREA IN RELATION TO THE 90*W MERIDIAN OF LONGITUDE. SEE TEXT P. 1

CULTURAL CHRONOLOGY - APPROXIMATE DATES

TCHEFUNCTE MARKS- TROY- VILLE I VILLE

5 0 0 7 0 0 8 5 0-J_________I______ ! _

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( M E T A I R I E -M IS S . ) EARLY ST. B E R N A R D S U B D E L T A

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>U B A R A T A R I A - R IV E R AUX C H E N E S O IO IO IO IOIOIOIOIOIOIOIOIOIOIOI

L A T E S T . B E R N A R D \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ S \ \ \ \ \ \ \ \ \

L A F O U R C H E - M I S S I S S I P P I

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L A T E S T . B E R N A R D S U B D E L T A \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

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B A L I Z E S U B D E L T A — — — — — — — — —

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T E D DELTAIC S H I F T S ON T H E VERMILION PA R ISH SH O R ELIN E’S A AND B FROM MC INTIRE 0 9 5 4 )

Figure 29

9 0 c m e r i d i a n , t h u s making i t a c o n v e n i e n t , though a r b i t r a r y ,

d i v i d i n g l i n e . A n c i e n t r i v e r s w i t h o u t l e t s t o t h e w e s t o f

t h i s l i n e u n d o u b te d ly g av e r i s e t o m u d f la t and marsh form a

t i o n , t h u s c r e a t i n g s t r a n d e d b e a c h e s or c h e n i e r s a l o n g t h e

V e r m i l i o n P a r i s h c o a s t ; w h e r e a s , r i v e r s d e b o u c h in g t o th e

e a s t , l e d t o beach f o r m a t i o n , t h r o u g h s h o r e l i n e r e t r e a t ,

a l o n g the c o a s t o f t h i s p a r i s h . An e x c e p t i o n t o t h e above

s t a t e m e n t i s found in t h e p r e s e n t B e l i z e d e l t a which p r o

j e c t s southward f a r enough t o a l l o w p o r t i o n s o f i t s d i s

c h arged s e d im e n t to r e a c h V e r m i l io n P a r i s h by u t i l i z i n g th e

w e s t e r l y c u r r e n t s . I t sh ou ld a l s o be n o t e d , t h a t t h e amount

o f s e d im e n t d i s c h a r g e d i n t o t h e G u l f through t h e Grand

R i v e r - B e l l e R i v e r c h a n n e l s , which breach ed th e Teche r i d g e ,

was p r o b a b ly s m a l l , n e v e r t h e l e s s , t h i s m a t e r i a l r e a c h e d t h e

G u lf westward o f th e 9GC V.' m e r i d i a n o f l o n g i t u d e .

The m ajor ea s tw a r d d e l t a i c s h i f t in F i s k ' s c h r o n o

l o g y ( F i g . 29b) o c c u r r e d when t h e r i v e r d i v e r t e d from i t s

L a fourche c o u r se t o t h e Ivietarie c h a n n e l . I t i s t h u s l o g i c a l

to assume t h a t t h e major s h o r e l i n e r e t r e a t , r e p r e s e n t e d by

F ro n t R idge in V e r m i l io n P a r i s h , b e g a n , a c c o r d i n g t o F i s k ,

a f t e r t h e r i v e r l e f t i t s L afou rch e c o u r s e , and c o n t i n u e d

d u r in g t h e t im e t h e tie t a r i e , La L o u t r e , and R i v e r aux Chenes

c h a n n e l s were o c c u p i e d . Subseq uent t o t h e f o r m a t i o n o f Front

R id g e , a v e r y s l i g h t s h o r e l i n e advance p o s s i b l y o c c u r r e d in

V e r m i l io n P a r i s h w i t h t h e o c c u p a t i o n o f t h e B a r a t a r i a d e l t a ;

147

h o w ev e r , t h e f o l l o v f i n g s h i f t t o t h e Bayou C h e n ie r c o u r s e

p r o b a b l y c a n c e l l e d t h i s a d v a n c e . N e x t t h e f o r m a t i o n o f t h e

B a l i z e s u b d e l t a a d v a n ce d th e s h o r e l i n e o f t h e p a r i s h G u l f -

ward f o r a s l i g h t d i s t a n c e . Thus i t a p p e a r s t h a t i f F i s k ’ s

c h r o n o l o g y i s u sed the p r e s e n t s h o r e l i n e o f V e r m i l i o n P a r i s h

c o u l d n o t p o s s i b l y be l o c a t e d more than a m i l e o r two g u l f -

ward from F r o n t R i d g e . However, a t t h e p r e s e n t t i m e , th e

d i s t a n c e from F r o n t R id g e t o t h e G u l f i s s i x t o s e v e n m i l e s .

In a d d i t i o n , t h e p o t t e r y found in t h e I n d i a n e a r t h

mounds l o c a t e d on F r o n t R idge i n d i c a t e s t h a t th e c h e n i e r was

fo rm e d , and i n h a b i t e d , by C o le s Creek ( 8 ^ 0 - 1 2 0 0 A. D . ) t im e

( M c l n t i r e , 1 9 5 4 ) . U s i n g F i s k ' s c h r o n o l o g y t h i s s i t u a t i o n i s

i m p o s s i b l e a s h i s p o s t u l a t e d s h i f t from th e L a fo u r c h e c o u r s e

t o t h e M e t a r i e c h a n n e l d i d n o t o c c u r u n t i l a p p r o x i m a t e l y

1150 A. D. In o t h e r w o r d s , t h e s h o r e l i n e r e t r e a t t h a t ga v e

r i s e t o t h e f o r m a t i o n o f F ron t R idge d i d n o t commence u n t i l

t h e a j p r o x i m a t e end o f C o l e s Creek t i m e , a s u p p o s i t i o n t h a t

i s r e f u t e d by t h e c u l t u r a l e v i d e n c e found i n V e r m i l io n

P a r i s h .

L i c l n t i r e ' s s u g g e s t e d c h r o n o l o g y more r e a d i l y f i t s

i n t o t h e o u t l i n e d i c t a t e d by t h e c h e n i e r s e q u e n c e . T h er e

f o r e , t h e s u c c e s s i o n o f c o u r s e s s u g g e s t e d by t h e p r e s e n t

w r i t e r ( F i g . 2 9 c ) i s b u t a s l i g h t l y m o d i f i e d and augmented

v e r s i o n o f M c l n t i r e ' s , e m p h a s i s b e i n g p l a c e d 011 t h e c o u r s e s

and minor s t r e a m s im p o r ta n t t o t h e c h e n i e r c h r o n o l o g y o f

S o u t h w e s t L o u i s i a n a . F o l l o w i n g t h i s p r o p o s e d s e q u e n c e ( F i g .

2 9 c ) , t h e F r o n t R id g e s h o r e l i n e p r o b a b l y r e p r e s e n t s t h e r e

t r e a t o c c a s i o n e d b y t h e s h i f t o f t h e r i v e r t o t h e Bayou

3 u r a t a r i a - R i v e r aux Chenes d e l t a and, s u b s e q u e n t l y , t o t h e

Late S t . Bernard d e l t a ( F i g . 3 0 ) . T h ese s h i f t s o c c u r r e d

d u r in g T r o y v i l l e and e a r l y C o l e s C reek t i m e . The fo l lo : \ r in g

s h i f t t o t h e L e f o u r c h e M i s s i s s i p p i c o u r s e , d u r i n g l a t e C o l e s

Creek t i m e , c r e a t e d t h e i n f l u x o f s e d im e n t n e c e s s a r y to

s e p a r a t e t h e F r o n t R idge s h o r e l i n e from the g u l f by m i l e s

o f marsh and f r i n g i n g mud f l a t s . I t s h o u l d be n o t e d t h a t

t h i s s e q u e n c e c a l l s f o r i n i t i a l o c c u p a t i o n o f F r o n t R idge

d u r i n g C o l e s Creek t i m e , a demand borne o u t by t h e c u l t u r a l

e v i d e n c e . L a t e r , w i t h t h e f o r m a t i o n o f t h e P la q u e m in e s su b

d e l t a , r e t r e a t a g a i n o c c u r r e d f o r m in g t h e t r e n d i n g r i d g e

o f C h en ie r au T i g r e . I n i t i a l I n d i a n o c c u p a t i o n o f t h i s

r i d g e was d u r i n g P la q u e m in e s t im e ( i u c l n t i r e , 1 9 5 4 J , w h ic h i s

i n a g reem en t w i t h t h e d e s c r i b e d s e q u e n c e o f r i v e r s h i f t s .

A e r i a l p h o t o g r a p h s o f t h e T i g r e P o i n t r e g i o n r e v e a l

t h a t i t i s composed o f numerous narrow , s a n d - s h e l l r i d g e s

s e p a r a t e d by s t r i p s o f m arsh . The r i d g e s u s u a l l y o v e r l i e

s o f t , s l i g h t l y o r g a n i c , b l u e g r a y c l a y s o f form er m u d f l a t s .

A lth o u g h t h e dom inant p r o c e s s o p e r a t i v e i n t h e T i g r e P o i n t

r e g i o n has been t h a t o f a c c r e t i o n , th e r i d g e s r e p r e s e n t

m inor r e t r e a t s and were p r o b a b l y formed d u r i n g m ajor

EVOLUTION OF THE VERMILION PARISH CHENIER COMPLEX(SEE ALSO RIVER SEQUENCE C H A R T - FIG. 2 9 PART C)

L a n d F o r m e d B y S e d i m e n t R e c e i v e d F r o m S a l e ?, C y p r e m o r t ,A n d T e c h e - M i s s i s s i p p i D i s c h a r g e — P r e v i o u s T o O c c u p a t i o n O f E a r l y S t . B e r n a r d S u b d e l t a

L a n d F o r m e d B y S e d i m e n t R e c e i v e d F r o m B o e u f - R e d , R e d - V e r m i l i o n , A n d G r a n d R i v e r D i s c h a r g e — P r e v i o u s T o O c c u p a t i o n O f B a y o u B a r a t a r i a , R i v e r A u x C h e n e s , A n d L a t e S t .B e r n a r d S u b d e l t a s

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L a n d F o r m e d B y S e d i m e n t R e c e i v e d F r o m B a l i z e A n d A t c h a f a l a y a D i s c h a r g e

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Figure 30

1 5 0

28s t o r m s . The g u l fw ard advance s i n c e P la q u em in es t im e can,

in p a r t , be a c c o u n t e d f o r th r o u g h e r o s i o n o f t h e Chenier au

T ig r e r i d g e s and t h e submerged s h o a l a r e a s t o t h e e a s t . The

d e t r i t u s o f t h e s e f e a t u r e s i s c a r r i e d t o th e T ig r e P o i n t

r e g i o n by th e westward d i r e c t e d lo n g s h o r e c u r r e n t s .

A nother f u c t o r w h ich h a s a i d e d t h e a c c r e t i o n a r y p>ro-

c e s s e s in V e r m i l io n P a r i s h i s t h e growth o f th e modern B a l i z e

s u b d e l t a . T h is d e l t a has prograded f a r t h e r southward than

any p r e v i o u s l y e x i s t i n g e a s t e r n d e l t a i c m ass , S o u th w es t

P a s s , which r e c e i v e s t h i r t y p e r c e n t o f M i s s i s s i p p i R iv e r

f l o w ( H o l i e , 1952 , p . 1 1 9 ) , p r o j e c t s southw estw ard be low

the 2 9 ‘ L p a r a l l e l o f l a t i t u d e . As t h e o f f s h o r e c u r r e n t s in

t h i s p o r t i o n o f t h e C u lf s e t t o th e w e s t (U. S. Coast P i l o t ,

1 949 , P* 4 6 ) , c l a y - s i z e d p a r t i c l e s d i s c h a r g e d a t Sou thw est

P a s s may d r i f t westward f o r hundreds o f m i l e s b e f o r e

s e t t l i n g a d i s t a n c e o f tw e n t y f e e t ( L e ip p o r , 1954; B a t e s ,

1 9 5 3 , p . 2154; Scruto n and i i o o r e , 1953; Kuenen, 19 5 0 , pp.

2 5 3 - 2 5 4 ) . A p o r t i o n o f t h e c l a y - s i z e d m a t e r i a l i s , o f

c o u r s e , f l o c c u l a t e d and d e p o s i t e d near Sou thw es t P a s s ; how

e v e r , t h e r e can be l i t t l e doubt t h a t , owing t o th e p o s i t i o n

o f the d i s c h a r g e a r e a and t h e o f f s h o r e c u r r e n t s , some o f

t h i s m a t e r i a l i s t r a n s p o r t e d westward f o r g r e a t d i s t a n c e s .

L oca l i n h a b i t a n t s s t a t e t h a t II. 0 . r i d g e , now l o c a t e d s e v e r a l hundred f e e t i n l a n d from the p r e s e n t s h o r e l i n e , was form ed , in i t s e n t i r e t y , by th e h u r r i c a n e o f A u g u s t ,1 915 .

151

F ig u r e 31 shows t h a t a l t h o u g h a c c r e t i o n i s dominant

in t h e T ig r e P o i n t a r e a t h e s h o r e l i n e i s r e t r e a t i n g t o th e

e a s t and w e s t . The r e t r e a t i s e s p e c i a l l y r a p id f a r t h e r

w e s t in Cameron P a r i s h . As p r e v i o u s l y p o i n t e d o u t both t h e

l o n g s h o r e and o f f s h o r e c u r r e n t s t r a n s p o r t m a t e r i a l w estward,

how ever , t h e a p p a ren t c o n c e n t r a t i n g o f sed im e n t in th e T ig re

P o i n t a rea i s r a t h e r d i f f i c u l t to e x p l a i n . The w r i t e r b e

l i e v e s t h a t t h i s c o n c e n t r a t i o n i s d epend en t upon the bottom

c o n f i g u r a t i o n o f t h e g u l f . Depth c o n t o u r s sw in g a b r u p t l y

shoreward near C hen ier au T ig re and t h u s o u t l i n e t h e w e s t

ern l i m i t o f th e e x t e n s i v e s h o a l a r e a s w h ich e x i s t t o th e

e a s t { F i g . 2 ) . P r e v i o u s to t h e r e c e n t i n f l u x o f sed im en t

from t h e A t c h a f a l a y a 3ay r e g i o n t h e s h o a l a r e a s and t h e i r

f l a n k i n g s h o r e l i n e s were d e v o id o f a f i n e se d im e n t c o v e r .

T h is c o n d i t i o n s u g g e s t s t h a t th e s e d i m e n t - l a d e n o f f s h o r e

c u r r e n t s from, th e - M i s s i s s i p p i d e l t a r e g i o n p r ob a b ly p a r a l l e l

the g u l fw a rd border o f t h e s h o a l s . C u rr en ts rou n d in g th e

s o u t h w e s t e r n e x t r e m i t y o f the s h o a l a r u a s p o s s i b l y s e t up a

c l o c k - w i s e eddy i n t h i s r e g i o n which would a i d in sed im en t

c o n c e n t r a t i o n . In a d d i t i o n , westward d i r e c t e d c u r r e n t s

c r o s s i n g th e s h o a l s would t en d to d e p o s i t suspended se d im e n t

near o b s t r u c t i o n s t o f l o w such as o y s t e r r e e f s , and i n the

r e l a t i v e l y d e e p , v e l o c i t y d i m i n i s h i n g , wuter o f t h e C hen ier

au T ig r e r e g i o n . The c o n t i n u i n g e n la rg e m en t o f t h e A t c h a f a

l a y a R iv e r and t h e o p e n in g o f th e V/ax la k e C u t o f f h a s g iv e n

T I f

SHORELINE CHANG AU TIGRE F

S H O R E L I N E O F 1 8 8 6

S H O R E L I N E O F 1951

L A N D L O S T BY E R O S I l

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ANGES IN THE PECAN ISLAND - CHENIER RE REGION BETWEEN 1886 & 1951

VERMILION BAY8 8 6 - F R O M U . S . C . 8 . C .S . C H A R T N O . 2 0 0 , 1 8 9 3 E D I T I O N - B A S E D

O N 1 8 8 6 S U R V E Y . ( C O R R E C T E D T O 1 9 2 7 N O R T H A M E R I C A N D A T U M .)

) 5 I - F R O M A E R I A L P H O T O G R A P H S F L O W N , S P R I N G 1 9 5 1 . JdR O S I O N B E T W E E N 1 8 8 6 & 1 9 5 1 _ £ ' •

f A C C R E T I O N B E T W E E N 1 8 8 6 & 1951

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153

r i s e t o t h e i n f l u x o f s e d i m e n t t h a t h a s g r e a t l y a c c e l e r a t e d

c o a s t a l a d v a n c e a l o n g t h e Llarsl i I s l a n d a n d V e r m i l i o n l a r i s h

s h o r e . C o a s t a l a d v a n c e i n t h e T i g r e l o i n t r e g i o n s i n c e 1927

h a s been a l m o s t f o u r t i m e s a s r a p i d a s d u r i n g t h e p r e c e d i n g

89 y e a r s (Morgan , Van L o p i k , a n d N i c h o l s , 1953 , p . 8 ) .

V/ave r e f r a c t i o n u n d o u b te d ly p l a y s an im p o r ta n t p o r t

i n c o n c e n t r a t i n g s e d im e n t i n th e T i g r e l o i n t r e g i o n ; how ever ,

d e t a i l e d i n f o r m a t i o n f o r t h i s a r e a i s n o t a v a i l a b l e . N e v e r

t h e l e s s , i t i s o b v i o u s t h a t t h e t r a n s p o r t i n g power o f s o u t h

e r l y waves i s d i s s i p a t e d nea r t h e Gulfwurd edge o f t h e

s h o a l s , ana the f i r s t l o c a l i t y , i n t h i s r e g i o n , whore nav es

from t h i s d i r e c t i o n co u ld t r a n s p o r t m a t e r i a l t o w i t h i n a

s h o r t d i s t a n c e o f t h e s h o r e l i n e i n n e a r C h en ier au T i g r e .

The pr need in/: p a g e s have t e n l t p r i m a r i l y w i t h t h e

p o s t - F r o n t Ridge s h o r e l i n e s . In t h e f o l l o w i n g d i s c u s s i o n o f

t h e o l d e r c h e n i e r s , i t i s ujnyurv. nt M c.t t h e i r c o r r e l a t i o n

w i t h s h i f t s o f t h e M i s s i s s i p p i d e l t a s I s n o t a s c e r t a i n a s

in th e c a s e o f t i ie younger r i d g e s , how ev er , a n y a n a l y s i s

o f t i ie p r e - F r o n t R idge c h e n i e r s sh o u ld ta k e i n t o a c c o u n t the

f o l l o w i n g f a c t s :

( 1 ) The o l d e r s h o r e l i n e r i d g e s a r e u s u a l l y composed

p r i m a r i l y o f o y s t e r s h e l l .

( 2 ) T e h e f u n c l e p o t t e r y i s fou n d on t h e r i d g e s p r o

j e c t i n g n o r t h e a s t w a r d from Back R i d g e .

( 3 ) B e l l e I s l e , an a b n o r m a l ly l a r g e b e a c h d e p o s i t ,

154

i s composed p r i m a r i l y o f s i l t and sand; n o t decomposed s h e l l

su c h a s u s u a l l y c o n s t i t u t e s t h e n e a r b y r i d g e s .

The w r i t e r b e l i e v e s the t e n t a t i v e e a r l y s h o r e l i n e

h i s t o r y o u t l i n e d b e lo w i s in k e e p i n g w i t h th e known f a c t s .

The g u l f w a r d c o n c a v i t y e x h i b i t e d by t h e e a r l y s h o r e

l i n e s o f V e r m i l io n P a r i s h i s p r o b a b l y due t o the p r e s e n c e o f

t i ie Bayou C y p r e m o r t - S a l e 1 d e l t a s to the s o u t h and s o u t h e a s t

and t h e r e l a t i v e "high" o f the I l e i s t o c e n e meander b e l t to

the w e s t ( P l a t e I , F i g . b and F i g . 1 6 ) . Ti i s r e g i o n , t h e r e

f o r e , p o s s i b l y o r i g i n a t e d a s a s h a l l o w d e l t a f l a n k d e p r e s

s i o n f l a n k e d by numerous o y s t e r r e e f s . Su bseq u en t i n f l u x o f

se d im e n t d u r i n g t h e o c c u p a t i o n o f th e Teohe-i.i i s s i a s i p p i

c o u r s e l e d t o a sp a sm o d ic s h o r e l i n e a d v a n c e , marked by minor

r e t r e a t s . The f l u c t u a t i o n s in t h i s advance were p r o b a b ly

due t o the ch a n g e s in w ate r volume and s e d im e n t lo a d o f th e

T e c h e - V e r m i l i o n , which d u r in g t h i s t im e p r o b a b ly d i s c h a r g e d

n e a r t h e p r e s e n t s i t e o f B e l l e I s l e . (The e a r l y h i s t o r y o f

t h e V e r m i l io n R i v e r , o u t l i n e d in t h e T e c h e - l ' i s s i s s i p p i s e c

t i o n — F i g . 2 5 , c e r t a i n l y seems t o i n d i c a t e t h a t g r e a t

c h an g es i n t h e w a t e r volume and s e d im e n t l o a d o f t h e s tr ea m

d id o c c u r . ) C o n c e n t r a t i o n o f sed im e n t a t t h i s p o i n t a l s o

h e l p s to e x p l a i n t h e s i l t - s a n d c o m p o s i t i o n o f B e l l e I s l e .

7/ ith th e s h i f t o f th e i l i s s i s s i p p i to the E a r l y S t .

Bernard d e l t a , s h o r e l i n e r e t r e u t p r e v a i l e d in V e r m i l io n l a r -

i s h , j i o s s i b l y g i v i n g r i s e t o t h e f o r m a t i o n o f Back R id g e .

155

T h i s would a l l o w t h e a p p a r e n t l y t r u n c a t e d r i d g e s p r o j e c t i n g

n o r t h e a s t w a r d from the i s l a n d t o be o c c u p i e d by I n d i e n s

d u r i n g e a r l y T c h e f u n c t e t i m e . A p o r t i o n o f t h e s e d i m e n t

w h ich p r o d u c e d t i ie c o a s t a l a d v a n ce from Buck R idge to s o u t h

o f t h e p r e s e n t l o c a t i o n o f F r o n t R id g e was p r o b a b l y b r o u g h t

i n t o t h e a r e a by t h e R e d - V e r m i l i o n ( f l o w i n g i n t h e T e c h e -

V e r m i l i o n c h a n n e l ) . A d d i t i o n a l s e d i m e n t was s u p p l i e d t o t h e

w estw a rd m oving l o n g s h o r e c u r r e n t by Grand R i v e r - B e l l e R i v e r

o u t l e t s and t h e d e s t r u c t i o n o f p r e - e x i s t i n g d e l t a s l o c a t e d

t o t h e e a s t o f V e r m i l i o n l a r i s h . The f o l l o w i n g r i v e r s h i f t s

t o t h e Bayou 3 a r a t u r i a - R i v e r au x Chenos and l a t e S t . B ern ard

d e l t a s l e d to s h o r e l i n e r e t r e a t and t h e f o r m a t i o n o f F r o n t

R i d g e . These l a t u e r , and s u b s e q u e n t , s h i f t s h a v e a l r e a d y

b een d i s c u s s e d and c o r r e l a t e d , w i t h a g r e a t e r d e g r e e o f c e r

t a i n t y , w i t h t h e c h e n i e r s e q u e n c e fo u n d in V e r m i l i o n l a r i s h .

The i n f o r m a t i o n p r e s e n t e d in t h i s s e c t i o n i s sum

m a r iz e d i n P a r t C o f F i g u r e 2y a n d - F i g u r e 3 0 .

MODERN CONDITIONS AND TRENDS IK CENTRAL COASTAL LOUISIANA

D e p o s i t i o n i s t h e dominant p r o c e s s o p e r a t i v e to d a y in

c e n t r a l c o a s t a l L o u i s i a n a . Avon though s h o r e l i n e r e t r e a t i s

a c t i v e a l o n g some o f th e bay s h o r e s , t h e s e w a ter b o d i e s a r e

s l o w l y b e i n g f i l l e d w i t h s e d im e n t b ro u gh t i n t o th e a r e a , f o r

the most p a r t , from t h e e a s t . The c o a s t a l a d v a n ce p r e s e n t l y

o c c u r r i n g a l o n g t h e g u l f shore o f V e r m i l io n I a r i s l i and the

f i l l i n g o f t h e A t c h a f a l a y a B a s in have been b r i e f l y m en t ioned

p r e v i o u s l y . The r e c e n t r e p o r t s o f E i sk ( 1 9 5 2 ) and I'organ,

Van L o p ik , and H io h o I s ( 1 9 5 3 ) d e a l p r i m a r i l y w i t h t h e s e d i

m e n t a t io n o c c u r r in g , i n t h e s e two a r e a s . The w r i t e r f e e l s

t h a t t h e c o n c l u s i o n s put f o r t h i n the above m en t ion ed p u b l i

c a t i o n s p r e s e n t au a d e q u a t e , c o n c i s e p i c t u r e o f th e p r e s e n t

c o n d i t i o n s and t r e n d s in c e n t r a l c o a s t a l L o u i s ia n a . These

c o n c l u s i o n s a r e rep ro d u c ed b e lo w .

? i s k ( 1 9 5 2 , pp. 1 4 0 - 1 4 2 ) :

The A t c h a f a l a y a d i s t r i b u t a r y i s f o l l o w i n g a d e v e l o p m e n t a l p a t t e r n c h a r a c t e r i s t i c o f form er M i s s i s s i p p i R iv e r d i v e r s i o n s e a c h o f which w i t h i n an e s t i m a t e d 100- y e a r p e r io d c a p t u r e d t h e e n t i r e f l o w o f t h e m a s te r s t r e a m . Now t h a t a c h a n n e l c a p a b l e o f c a r r y i n g lo w - w a te r f l o w h a s b een e s t a b l i s h e d and e n la r g e m e n t has be gun, 110 n a t u r a l p r o c e s s e s a r e known which in t h e c a s e o f t h e A t c h a f a l a y a m ig h t p r e v e n t f u r t h e r e n la r g e m e n t and e v e n t u a l d i v e r s i o n o f th e e n t i r e M i s s i s s i p p i f l o w .

The A t c h a f a l a y a a t t h e p r e s e n t t ime i s in i t s i n t e r m e d ia t e s t a g e o f d i v e r s i o n . E n g i n e e r i n g s t u d i e s show t h a t a p p r o x i m a t e l y t w e n t y - f i v e per c e n t o f t h e w a te r o f t h e M i s s i s s i p p i i s b e i n g d i v e r t e d . The p r e s e n t s tu d y

1 5 6

157

h a s shown t h a t a c r i t i c a l s t a g e i s t o be e x p e c t e d a t some t i m e b e f o r e f i f t y p e r c e n t o f t h e f l o w i s d i v e r t e d . F o l l o w i n g t h i s c r i t i c a l s t a g e , c l o s u r e o f t h e M i s s i s s i p p i R iv e r b e l o w Old R iv e r w i l l be r a p i d and d i v e r s i o n w i l l be r e l a t i v e l y u n c o n t r o l l a b l e . A c o n s e r v a t i v e maximum e s t i m a t e a s t o when the c r i t i c a l s t a g e w i l l o c c u r i s based on th e t im e o f f o r t y p e r c e n t d i v e r s i o n . Trends e s t a b l i s h e d by p r e s e n t m e a s u r a b le r a t e s o f A t c h a f a l a y a d eve lop m en t a r e a s f o l l o w s :

a . The t r e n d e s t a b l i s h e d by t h e p e r c e n t a g e o f t o t a l a n n u a l f l o w d i v e r t e d from t h e M i s s i s s i p p i through Old R i v e r shows t h a t f o r t y p e r c e n t o f t h e M i s s i s s i p p i f l o w w i l l be d i v e r t e d by 1 9 7 1 .

b . Trends b a s e d on the t im e when t h e c h a n n e l o f Old R i v e r and t h e upper A t c h a f a l a y a R iv e r w i l l have s u f f i c i e n t c r o s s - s e c t i o n a l a r e a t o a c c e n t f o r t y , p e r c e n t o f t h e f l o w o f t h e M i s s i s s i p p i , b r a c k e t t h e t i n e b e tw een 1965-75*

c . Trends b a s e d on t h e r a t e o f f i l l i n g o f Grand la k e and th e e s t a b l i s h m e n t o f a c h a n n e l from t h e head o f th e A t c h a f a l a y a d i s t r i b u t a r y to i t s mouth in A t c h a f a l a y a Bay, show t h a t t h i s c o n d i t i o n can be e x p e c t e d be tw een 1 9 7 0 - 7 5 .

d . Trends b a s e d on th e r a t e o f bank m i g r a t i o n and c h a n n e l e n la r g e m e n t a t th e p o i n t o f d i v e r s i o n i n d i c a t e t h a t a c r i t i c a l s t a g e o f d i v e r s i o n w i l l be r e a c h e d in 1 97 0 .

I t i s c o n c lu d e d , t h e r e f o r e , t h a t under norm al c o n d i t i o n s o f d e v e lop m en t t h e d i v e r s i o n w i l l have r e a c h e d a c r i t i c a l s t a g e be tw een t h e y e a r s 1 9 6 5 - 7 5 .

F a c t o r s wh ich w i l l a c c e l e r a t e t h e d i v e r s i o n n r y p r o c e s s a re t h e f r e q u e n c y o f f l o o d s or s u s t a i n e d h i g h - w a t e r f l o w s th ro u gh t h e d i s t r i b u t a r y , c o n t i n u e d d r e d g i n g in t h e lo w er A t c h u f a l a y a B a s i n , and a c r i t i c a l s t a g e o f d eve lop m en t o c c u r r i n g b e f o r e the- t im e o f f o r t y p e r c e n t d i v e r s i o n . In c o n n e c t i o n w i t h t h i s l a s t f a c t o r , any sudden i n c r e a s e i n d e t e r i o r a t i o n o f t h e M i s s i s s i p p i c h a n n e l im m e d ia t e ly b e lo w t h e p o i n t o f d i v e r s i o n sh o u ld be i n t e r p r e t e d a s m arking t h e b e g i n n i n g o f t h e c r i t i c a l s t a g e .

Morgan, Van L o p ik , and H i c h o l s ( 1 9 5 5 , p . 3A):

D e p o s i t i o n o f f i n e c l a y or "mud" has o c c u r r e d a l o n g t h e w e s t e r n L o u i s ia n a c o a s t f o r a d i s t a n c e o f about f i f t y m i l e s d u r i n g t h e l a s t f i v e y e a r s . The f i n e c l a y in p l a c e s h a s formed r a t h e r broad m u d f l a t s seaward from s i l t and s h e l l b e a c h e s . The m u d f la t s a r e u n d e r l a i n by s o f t c l a y and s i l t d e p o s i t s which v a r y t o a maximum o f

1 5 8

some s i x f e e t . In some p l a c e s the m u d f la t s c o n s i s t o f v e r y u n i form , f i n e - g r a i n e d c l a y , w h i l e i n o t h e r s t h e r e a re t h i n s i l t p a r t i n g s i n t h e mud d e p o s i t s . The s o f t , o o z y mud i n some p l a c e s o v e r l i e s e r o d e d , f i r m , marsh c l a y s and i n o t h e r p l a c e s s i l t y beach m a t e r i a l s .

L o c a l i z e d mud c o n c e n t r a t i o n , i n t h e form o f f l a t s , i s n o r m a l ly a s l o w p r o c e s s but i s o f t e n a c c e l e r a t e d by s o u t h e r l y s to rm w i n d s . I f t h e m u d f l a t s a r e n o t removedby s u b s e q u e n t s t o r m s , v e g e t a t i o n soon a l t e r s t h e b a r r en f l a t s i n t o c o a s t a l m arsh . One g r o w in g s e a s o n w i l l o f t e n c o n v e r t l a r g e a r e a s t o o y s t e r g r a s s m arsh . The f i n e g r a i n e d mud seem s t o be e x t e n d i n g i t s e l f g r a d u a l l y i n a w e s t e r l y d i r e c t i o n and a t p r e s e n t i s v i r t u a l l y c o n t i n u ous a s f a r w e s t a s t h e mouth o f R o l l o v e r Bayou. A few i s o l a t e d p a t c h e s o f mud f l a n k the beach even f a r t h e r t o the w e s t .

The m a t e r i a l f o r m in g t h e m u d f l a t s i s M i s s i s s i p p i R i v e r se d im e n t which i s b e i n g c a r r i e d t o t h e G ulf by th e A t c h a f a l a y a R iv e r d i s t r i b u t a r y o f t h e M i s s i s s i p p i R i v e r sy s t e m . The A t c h a f a l a y a h a s i n c r e a s e d i t s p r o p o r t i o n o f t o t a l M i s s i s s i p p i R i v e r f l o w a p p r e c i a b l y d u r in g the l a s t f i v e t o ten y e a r s . The A t c h a f a l a y a R iv e r d i s c h a r g e s i t s w a t e r s and s e d im e n t i n t o l a r g e s h a l l o w l a k e s (Grand Lake and S i x - M i l e Lake) w h ich s e r v e as s e t t l i n g b a s i n s , a t l e a s t f o r t h e c o a r s e r p a r t i c l e s . F i n e - g r a i n e d muds r e main in s u s p e n s i o n and a r e c a r r i e d i n t o A t c h a f a l a y a Bay by t h e Lower A t c h a f a l a y a R i v e r and th e a r t i f i c i a l l y co n s t r u c t e d V/ax Lake o u t l e t . Most o f t h e mud r e m a in s in s u s p e n s i o n u n t i l c a r r i e d beyond th e l i m i t s o f t h e e s s e n t i a l l y f r e s h - w a t e r b a y . Unce beyond t h e l i m i t s o f th e bay t h e f i n e muds are c a r r i e d w estw a rd a l o n g t h e c o a s t by p r e v a i l i n g l o n g s h o r e c u r r e n t s . T h i s p r o c e s s i s r e s u l t i n g i n t h e s t r a n d i n g o f o l d s i l t and s h e l l b e a c h e s b e h in d a zone o f n e w l y - d e v e l o p i n g m u d f l a t m arsh .

I f th e M i s s i s s i p p i i s a l l o w e d t o d i v e r t i n t o th e

A t c h a f a l a y a c h a n n e l , o b v i o u s l y g r e a t ch a n g e s would o c c u r i n

t h e c o a s t a l a r e a o f c e n t r a l L o u i s i a n a . K ven ts su ch a s th e

c o m p le t e f i l l i n g o f Grand and S i x - M i l e L a k es , g r e a t e n l a r g e

ment in th e w i d t h o f t h e A t c h a f a l a y a R i v e r , t h e b u i l d i n g o f

an e v e r - e x p a n d i n g d e l t a i n t h e p r e s e n t A t c h a f a l a y a Bay

r e g i o n , and r a p i d c o a s t a l advance i n t h e w e s t e r n p a r i s h e s

would c e r t a i n l y t a k e p l a c e . R e v o l u t i o n a r y a s t h e s e c h a n g e s

seem, s i m i l a r m o d i f i c a t i o n s have ta k e n p l a c e many t i m e s in

t h e R e c e n t h i s t o r y o f c o a s t a l L o u i s i a n a and m e r e ly r e p r e s e n t

an a c c e l e r a t i o n o r s h i f t o f p r o c e s s e s now o p e r a t i v e .

tO S SIB LIS EFFECTS OF I.CODERIJ SEA LEVEL

RISE OH COASTAL LOUISIANA

I n t h e l i g h t o f d a t a p r e s e n t e d by Marmer ( 1 9 4 8 , 1952^

t h e r e seem s t o be j u s t i f i c a t i o n i n a s s u m in g t h a t a r i s e o f

s e a l e v e l , a t l e a s t a l o n g t h e c o a s t s o f t h e U n i t e d S t a t e s ,

i s t a k i n g p l a c e a t t h e p r e s e n t t i m e . I n h i s d i s c u s s i o n o f

t h e G u l f C o a s t a r e a I.iarmer ( 1 9 5 2 , p . 6 7 ) s t a t e s :

For G a l v e s t o n t h e r e s u l t s a r e e s p e c i a l l y i n t e r e s t i n g s i n c e a c o n t i n u o u s s e r i e s o f f o r t y y e a r s i s a v a i l a b l e . D u r in g t h i s t im e s e a l e v e l h a s cha nged by a l m o s t e x a c t l y one f o o t , b u t t h e r e s u l t s c l e a r l y i n d i c a t e a change i n r a t e o f r i s e b e tw een 1937 and 1 9 3 8 . From 1909 t o 1937 t h e r i s e w as a t a r a t e o f a b o u t 0 . 0 1 5 f o o t p e r y e a r , w h i l e s i n c e t h a t y e a r t h e r i s e i s a t th e r a t e o f a b o u t 0 . 0 5 f o o t p er y e a r or more t h a n t h r e e t i m e s t h e p r e v i o u s r a t e .

A r a p i d a c c e l e r a t i o n o f r i s e s i n c e t h e 1 9 3 0 ’ s i s a l s o

n o t e d a l o n g t h e A t l a n t i c a n d , t o a l e s s e r d e g r e e , l a c i f i c

c o a s t s . I t i s e x t r e m e l y d o u b t f u l t h a t t h i s a c c e l e r a t i o n h a s

been c a u s e d b y a r e c e n t pro n o u n ced i n c r e a s e i n l ' e g i o n a l s u b

s i d e n c e , t h e r e f o r e , t h e movement m ust be a c c e p t e d , i n p a r t ,

a s a d e f i n i t e i n d i c a t i o n o f a r e c e n t r i s e i n s e a l e v e l .

Numerous g l a c i a l g e o l o g i s t s have a l s o p r e s e n t e d i n

f o r m a t i o n i n d i c a t i n g r e c e n t s h r i n k a g e o f g l a c i a l v o lu m e ,

due t o a g e n e r a l warming o f t h e c l i m a t e , t h u s , d i c t a t i n g a

r i s e i n s e a l e v e l . M a t t h e s ( 1 9 4 5 , p . 2 3 1 ) s t a t e s :

. . . n o t o n l y h a s g l a c i e r s h r i n k a g e b e e n g e n e r a l i n b o t h H e m is p h e r e s d u r i n g t h e l a s t n i n e t y y e a r s , b u t e v e n some o f t h e l e s s e r v a r i a t i o n s durl xig t h a t p e r i o d

160

161

have s y n c h r o n i z e d r a t h e r c l o s e l y , Most r em a rk a b le i s t h e sy n c h r o n ism o f t h e l a t e s t p h a s e - - t h e 3h a r p l y a c c e l e r a t e d r e c e s s i o n d u r i n g t h e l a t e r 1 9 3 0 f s . THORAK- IKaSON c h a r a c t e r i s e d i t a s " c a t a s t r o p h i c ; " SiLIGIiT termed i t "abnormal" ( p e r s o n a l com m unicat ion d a te d December 3 1 , 1 9 4 0 ) , and BROGGI c a l l s i t "unusual" ( a c e l e r a c i o n i n u s i t a d a ) .

In h i s e x c e l l e n t and co m p reh en s ive p a p e r , T h o r a r i n s -

son ( 1 9 4 0 , p. 151) o p i n e s t h a t "The i c e - t h i n n i n g i n t h e l a s t

few d e c a d e s o f t h e w o r l d ' s g l a c i e r d i s t r i c t s , e x c l u s i v e o f

t h e whole A n t a r c t i s and th e a c c u m u l a t io n a r e a o f G reen land

i c e , has t h u s - - c e t e r i s p a r i b u s - - r e s u l t e d i n t h e o c e a n l e v e l ' s

b e i n g r a i s e d e u s t a t i c a l l y ab o u t 0 . 0 5 cm ( 0 . 0 2 i n . ) p er

annum." T h o r a r in s s o n b e l i e v e s t h e f i g u r e o f 0 . 0 5 cm per

annum to be the minimum r i s e n e c e s s i t a t e d by g l a c i e r m e l t i n g .

M e t e o r o l o g i s t s a re c o g n i z a n t o f t h i s t re n d t o a

warmer c l i m a t e . For e x a m p le , W i l l e t ( 1 9 1 9 , p . 13) makes

n o t e o f ". . . th e marked s e c u l a r tren d o f th e l a s t s i x t y

y e a r s ( 1 8 8 0 - 1 9 4 0 ) i n a l l p a r t s o f the world toward th e

s h r in k a g e o f g l a c i e r s , d r y i n g up o f l a k e s , and th e i n c r e a s e

o f t e m p e r a t u r e i n t h e h i g h e r l a t i t u d e s . "

The e c o n o m i s t w i l l i a m J . B a x t e r (1 9 5 3 ) i n h i s book

Today* s R e v o l u t i o n i n W eather c i t e s xmmerous r e p o r t s o f s e a

l e v e l r i s e und c l i m a t i c a m e l i o r a t i o n from a l l o v e r t h e

w o r l d .

B e fo r e d i s c u s s i n g the p o s s i b l e e f f e c t s o f a h y p o t h e

t i c a l s e a l e v e l r i s e o f a p p r o x i m a t e l y f i f t e e n f e e t on c o a s t

a l L o u i s i a n a t h e w r i t e r would l i k e t o em p has ize s e v e r a l

f a c t s . F i r s t l y , a l t h o u g h t h e r e con be l i t t l e doubt t h a t a

e u s t a t i c r i s e i n s e a l e v e l i s i n p r o g r e s s t o d a y t h e amount

o f a s c e n t i n d i f f e r e n t p a r t s o f t h e v /o r ld , due t o l o c a l and

r e g i o n a l c o n d i t i o n s , w i l l c e r t a i n l y v a r y i n m a g n i tu d e . For

e x a m p le , c o a s t a l a r e a s e x p e r i e n c i n g t e c t o n i c u p l i f t o r g l a -

c i o - i s o s t a t i c a d j u s t m e n t may e a s i l y e x h i b i t , d e p e n d in g on

th e amount o f u p h e a v u l , no e v i d e n c e o f se a l e v e l r i s e or

p o s s i b l y a downward m ovem ent .29 T h e r e f o r e , the a c t u a l

amount o f s e a l e v e l r i s e can be a c c u r a t e l y m easured o n l y

a l o n g th e c o a s t o f an a b s o l u t e l y s t a b l e a r e a , and a s t h e

m a j o r i t y o f s t r u c t u r a l g e o l o g i s t s e i t h e r c a n n ot a g r e e on t h e

l o c a t i o n o f su ch a r e g i o n or doubt th e e x i s t a n c e o f same,

t h e w r i t e r b e l i e v e s t h a t t h e b e s t e s t i m a t e s o f t h e e u s t a t i c

c h a n g e , i n a c c u r a t e a s t h e y may b e , are t h o s e made by th e

g l a c i a l g e o l o g i s t s bused on vo lum es o f g l a c i e r l o s s .

S e c o n d l y , t h e r e i s no d e f i n i t e p r o o f t h a t t h e p r e s e n t

c o n d i t i o n s r e p r e s e n t a minor s e c u l a r f l u c t u a t i o n , t h e b e g i n

n i n g o f a m ajor c l i m a t i c t r e n d , or a minor f l u c t u a t i o n

su p e r im p o sed on a major t r e n d . The r a p i d i t y o f change s i n c e

t h e 1 9 3 0 ’ s , how ev er , seem s t o f a v o r t h e minor f l u c t u a t i o n

h y p o t h e s i s .

^9 Marmer ( 1 9 5 2 , p . 66) i n d i c a t e s t h a t s e a l e v e l has been f a l l i n g a l o n g t h e c o a s t o f A la s k a s i n c e 1 9 4 0 . V a le n t i n ' s ( 1 9 5 2 , T a f e l 2) r e c e n t map, sh o w in g t h e r e l a t i v e movement o f t i i e w o r l d ' s c o a s t s , i n d i c a t e s th e g r e a t v a r i a t i o n s o f a p p a r e n t s e a l e v e l movement t h a t can r e s u l t from l o c a l and r e g i o n a l c o n d i t i o n s .

Thirdly, i t should be borne in mind tha t the follow

ing discussion of the e f fe c ts of sea leve l r i s e app lies p r i -

.nurily to co as ta l Louisiana and, due to the M y conf l ic t ing

processes operative in apparently s im ilar a re a s , should not

necessa r i ly be considered ty p ic a l of a l l de l ta regions,

The low co as ta l areas of Louisiana extend inland for

dis tances of from twenty-five to n inety miles before elevations

of f i f t e e n f e e t above sea leve l are reached (exclusive of i so

la ted beach r idges or lev ees ) . The normal t i d a l f luc tua t ion

along t h i s coast i s l e s s than two f e e t , Hurricanes have

ra ised water le v e ls in cer ta in areas by approximately ten ■

fe e t , In view of the above f a c t s a slow e u s ta t ic sea leve l

r i s e of ten or f i f t e e n f e e t would apparently have d i re r e s u l t s ,

LeBlanc and Bernard ( l c;% ) have depicted the apparent e f fe c t s

of a f i f t e e n foot r i s e in sea leve l on coas ta l Louisiana,

(Fig, 32a and b ) , however, other concurrently operative pro

cesses would undoubtedly make the e f f e c ts of such a r i s e

decidedly l e s s pronounced, Consider, for example, the e f

fe c t of a slow sea le v e l r i s e on the M ississippi Liver,

which contro ls co as ta l development in Louisiana, During

th i s r i s e a l e s s e r volume of flood water would overtop the

banks, thus making flood contro l more d i f f i c u l t , however,

levee formation should keep pace with the sea leve l ascent,

and flood stage should remain f a i r l y constant, Another

e f f e c t of t h i s overtopping would be an increased tendency

for crevasse channel formation and the adoption of a shor te r

course to the gu lf , e i th e r by ( l ) extension of a crevasse

channel, (2) occupation, through crevassing or l a t e r a l junc

t io n , of a c lose ly p a r a l l e l flowing stream course, or more

probably, (3) occupation of a su i tab le e x is t ing d is t r ib u ta ry ,

such as the Atchafalaya.

This d iversion would thus bring about the t r a n s f e r

ence of the g u l f discharge area of the M iss iss ipp i River from

i t s p resent loca t ion in water th a t rap id ly reaches a depth

of s ix ty f e e t to the shallow Atchafalaya Bay region, The

d e l ta formed in t h i s shallow embayinont would requ ire a pro-

gradation of over fo r ty miles before a water depth of s ix ty

f e e t i s reached. Therefore, i t is apparent th a t the de l ta

formed here would d i f f e r r a d ic a l ly in i t s appearance from

the present b i rd s - fo o t d e l ta of the M iss iss ipp i , li'ith the

same volume of sediment being deposited in the Atchafalaya

Bay area as i s p resen tly discharged a t the Mississippi

mouths, the new de l ta would assume a more ty p ic a l fan-shaped

ou t l ine c h a ra c te r i s t i c of most pre-Balize M iss iss ipp i d e l ta s ,

La te ra l and gulfward expansion would take place a t a pheno

menal r a t e , and growth would occur in sp i te of a r i s i n g sea

leve l , In o ther words, the shoreline of the c e n t ra l one th ird

of Louisiana would d e f in i t e ly maintain i t s e l f and, in a l l

p rob a b i l i ty , advance even in the face of a r e l a t iv e ly rapid

sea leve l r i s e (Fig, 32c), The shoreline of the western one

POSTULATED EFFECTS OF A F IF T E E N -F O O T RISE IN SEA LEVEL ON COASTAL LOUISIANA

SCALE IN MILES

[OPELOUSAS 9.

•n e w o r l e a n s

FRANKLIN

/ \ MODERN C O A S T A L P L A IN . (FR O M L E B L A N C A N D B E R N A R D , 1 9 5 4 )

Figure 32

FRANKLIN

AREAS THAT WOULD BE FLOODED BY A 15 - FOOT RISE IN SEA LEVEL. (FROM LE BLANC AND BERNARD, 1954)

O 10 20 30 4 0 50

SC A L E IN M ILES

ROUGE

HARLCS

NEW ORLEANS

S 3FRANKLIN

HOUMA

AREAS THAT WOULD BE FLOODED BY A 15-FOOT RISE IN SEA LEVEL IF CONTINUING MISSISSIPPI RIVER SEDIMENTATION IS CONSIDERED.

RECENT

LATE PLEISTOCENE

/ ) 5 C

LEGEND

ABANDONED MISSISSIPPI RIVER MEANDER BELTS AND DISTRIBUTARY CHANNELS. (AFTER FISK,1952)

ABANDONED BEACH RIDGES.

MISSISSIPPI RIVER MEANDER BELTS.

RED RIVER MEANDER BELTS.

165

1 6 6

t h i r d o f t h e s t a t e would r e t r e a t s l i g h t l y , o r p o s s i b l y m ain

t a i n i t s e l f due t o t h e i n f l u x o f s e d i m e n t c a r r i e d by t h e

w estw ard t r e n d i n g c u r r e n t s . The s h o r e l i n e o f t h e e a s t e r n

one t h i r d o f L o u i s i a n a , h o w e v e r , due t o t h e combined e f f e c t s

o f s u b s i d e n c e , s e a l e v e l r i s e , and t h e l a c k o f a n e a r b y

s e d i m e n t s u p p l y would u n d o u b te d ly r e t r e a t . The c o a s t a l o u t

l i n e o f t h i s e a s t e r n a r e a would c o n s i s t o f two embayruents

(one i n th e Lake B o r g n e - M i s s i s s i x v p i Sound r e g i o n ; th e o t h e r ,

i n th e B a r a t a r i a Bay-Lake S a l v a d o r - T i m b a l i e r Bay a r e a ,

f l a n k i n g t h e e a s t e r n s i d e o f t h e A t c h a f a l a y a d e l t a ) p a r

t i a l l y s e p a r a t e d by a s h o r t p r o n g o f l a n d composed o f t h e

rem nan ts o f t h e p r e s e n t M i s s i s s i p p i l e v e e s w h ic h e x te n d

s o u t h e a s t w a r d from Hew O r l e a n s . Thus i t i s e a s i l y p o s s i b l e ,

u s i n g p r e s e n t day du ta and t r e n d s , t o v i s u a l i z e a s i t u a t i o n

i i i w h ic h a f i f t e e n f o o t r i s e o f s ea l e v e l w ou ld r e s u l t i n

b u t s l i g h t a r e a l l o s s to t h e c o a s t o f L o u i s i a n a .

B a r to n ( 1 9 2 3 ) h as p r e v i o u s l y s u g g e s t e d t h a t n t e n

f o o t r i s e i n s e a l e v e l , or su b m e rg e n c e , would have l i t t l e

e f f e c t on t h e lo w e r c o u r s e s o f s t r e a m s " t h a t a r e f l o w i n g

w it h t h e i r w a t e r l e v e l a t , and th e b o t to m o f t h e i r c h a n n e l

a c o n s i d e r a b l e d i s t a n c e b e l o w , th e w a t e r l e v e l o f a l a k e ,

b a y , g u l f , or o c e a n i n t o which t h e y a r e f l o w i n g . " B a r to n

d e a l s m a i n l y w i t h t h e e f f e c t o f s e a l e v e l r i s e on t h e mean

d e r i n g t e n d e n c i e s i n t h e l o w e r p o r t i o n o f r i v e r s such a s

th e B r a z o s , and a l t h o u g h rr wandering i n t h e d i s t a l p o r t i o n o f

167

the M i s s i s s i p p i has been c u r t a i l e d due to t h e c o m p o s i t i o n o f

i t s b e d , t h e p r e s e n t w r i t e r b e l i e v e s t h a t t h e t e n d e n c y to

meander i s i n h e r e n t , t h u s n u k in g some o f B u r t o n ’ s remarks

a p p l i c a b l e t o t h e M i s s i s s i p p i R i v e r . B arton ( 1 9 2 8 , p . 620)

s t a t e s :

A submergence o f t e n f e e t , w h ich i s g r e a t e r th a n th e p r o b a b le submergence i n t h e lo w e r c o u r s e s o f t h e San J a c i n t o R i v e r , presu m ab ly would n o t ca u se any v e r y g r e a t change in t h e b e h a v i o r o f t h e B r a zo s R iv e r in t h e lo w er 48 1 / 2 m i l e s o f i t s c o u r s e . . .

I f a s lo w s u b s i d e n c e w ere o c c u r r i n g , p r o g r e s s i v e l y l e s s e r f l o o d s would s e n d t h e s tr ea m o u t o f i t s banks; and t h e b u i l d i n g up o f l e v e e s would be i n c r e a s e d c o n c o m i t a n t l y end w ou ld p r o b a b ly keep puce w i t h th e s u b s i d e n c e . The mean g r a d i e n t both o f t h e w a ter l e v e l and th e b o t to m o f t h e c h a n n e l would be s l i g h t l y d e c r e a s e d f o r the whole s t r e t c h be low B o l i v a r F a l l s . I f th e b ottom o f th e c h a n n e l were n o t b u i l t up t o k eep puce w i t h th e l e v e e s , the e f f e c t i v e volum e o f t h e c h a n n e l would be o v e r s i z e i n r a t i o t o t h e volume o f s tream f l o w and would tend t o r e d u c e t h e s t r e a m v e l o c i t y , which i n tu r n would f a v o r ' - d e p o s i t i o n and f i l l i n g o f the c h a n n e l u n t i l the r a t i o o f c h a n n e l c a p a c i t y t o th e volume o f th e s tr ea m f l o w w ere b rou g h t back t o i t s p r e s e n t v a l u e . The n a t u r a l l e v e e s and t h e bottom o f t h e ch a n n e l o f t h e meander n e a r F r e e p o r t would be b u i l t up s i m u l t a n e o u s l y , and the same c o n d i t i o n s o f s tr ea m f l o w would th e n p r e v a i l a s a t p r e s e n t , and t h e meander s h o u ld c o n t i n u e t o move sea w a rd , u n l e s s , o r u n t i l , o b l i t e r a t e d by th e r e t r o g r e s s i o n o f th e sh o r e l i n e c o n s e q u e n t upon th e s u b s i d e n c e . The whole l o w e r c o u r se o f t h e s t r e a m from above Richmond t o t h e g u l f u l t i m a t e l y s h o u ld become a d j u s t e d t o a c r o s s - s e c t i o n l i k e t h a t a t p r e s e n t and to a l o n g i t u d i n a l p r o f i l e w i t h a v e r y s l i g h t l y lo w er moan g r a d i e n t than the p r e s e n t o n e . Y e t i t seem s d o u b t f u l t h a t t h e g r a d i e n t would be l e s s a t any p o i n t th a n th e p r e s e n t g r a d i e n t in t h e s t r e t c h 'where the F r e e p o r t meander i s a c t i v e l y m oving . The c o n c l u s i o n t h e r e f o r e f o l l o w s t h a t th e p r e s e n t t e n d e n c y t o m ean der in g would c o n t i n u e i n t h e low er r e a c h e s o f t h e B razos even i n f a c e o f a p r o g r e s s i v e s lo w s u b s i d e n c e .

I f t h e s u b s i d e n c e were su dd en , s h o r e l i n e e r o s i o n and a l o n g s h o r e c u r r e n t s m ig h t o b l i t e r a t e th e l o w e s t few m i l e s o f the s t r e a m , b u t in g e n e r a l th e p r e s e n t c h a n n e l , a i d e d by th e n a t u r a l l e v e e s , would t e n d t o h o l d th e

1 6 8

c u r r e n t t o i t s p r e s e n t c o u r s e j u s t a s now hap pens in t im e o f h ig h f l o o d ; t h e l e v e e s would t e n d t o be b u i l t up to t h e new g u l f l e v e l , and a t t i m e s o f f l o o d , above i t ; and t h e r i v e r would t e n d u l t i m a t e l y t o a d j u s t i t s e l f t o t h e same p r o f i l e as i f the s u b s i d e n c e had b e e n s l o w and p r o g r e s s i v e . . .

T h e r e f o r e , t h e s u p p o s i t i o n t h a t a t e n o r f i f t e e n f o o t

s e a l e v e l r i s e would n o t b r i n g a b o u t any g r e a d a r e a l l o s s to

t h e L o u i s i a n a c o a s t a l r e g i o n s o r xj**oduce any g r e a t ch a n g e s

( a s i d e from p o s s i b l e d i v e r s i o n s ) i n t h e Gulfward f l o w i n g

s t r e a m s seem s j u s t i f i e d . C o n s e q u e n t l y , i f such a sea l e v e l

r i s e h a s t a k e n p l a c e d u r i n g ho cen t t im e i t s o c c u r r e n c e

would be d i f f i c u l t t o a s c e r t a i n on t h e b a s i s o f e v i d e n c e

t h a t m ight p o s s i b l y be found in t h e d e l t a i c p o r t i o n s o f

L o u i s i a n a , T h is e v i d e n c e , a l s o , c o u l d e a s i l y be d e s i g n a t e d

a s e f f e c t s o f s u b s i d e n c e or d e l t a i c s h i f t s , t h u s making

i n t e r p r e t a t i o n d o u b ly d i f f i c u l t .

smnriARY

On t h e p r e c e d i n g p a g e s an a t t e m p t h a s b e e n made t o

o u t l i n e t h e l a t e Q u atern ary h i s t o r y o f s o u t h c e n t r a l L o u i s i

a n a . A r b i t r a r i l y b e g i n n i n g t h e h i s t o r i c a l e x a m i n a t i o n w i t h

th e E a r l y 'W isconsin g l a c i a l s t a g e , the o r i g i n o f t h e s e d i

m en ts now e x p o s e d i n t h e a r e a and t h e m o d i f i c a t i o n s g i v i n g

r i s e to t h e i i r e n c n t to p o g r a p h y have b e e n d i s c u s s e d . The

t h o u s a n d s o f f e e t o f p r e - e x i s t i n g s e d i m e n t s t h a t u n d e r l i e

t h i s r e g i o n h a v e , t h u s , been more o r l e a s i g n o r e d . I t

s h o u ld be borne in mind , how ever , t h a t riany o f t h e t e c t o n i c

t r e n d s o f t h e s e old«..r s t r a t a a re r e f l e c t e d i n the o v e r l y i n g

1 ua t e rna r y d cm o s i t s .

D u ring t h e m arly W i s c o n s i n g l a c i a l s t a r e the a m a ss

ment and cxpar.s i ; o f th e po ’ ee s h e e t s r e s u l t e d in a

l o w e r i n g o f s e a l e v e l . T h i s drop i n sea l e v e l f o r c e d t h e

G u l f C o a s t s t r e a m s t o e n t r e n c h and t h u s c u t deep v a l l e y s

i n t o t h e p r e - e x i s t i n g T e r t i a r y and ^ a r l y P l e i s t o c e n e s e d i

m e n t s , which ware In t i i e p r o c e s s o f b e i n g downwarped toward

th e g u l f and u p l i f t e d i n l a n d . D u r in g t' i s t ime l a r g e q u a n t i

t i e s o f c o a r s e san d s and g r a v e l were c a r r i e d t o th e g u l f .

With th e e l im a t i c a m e l i o r a t i o n and g l a c i a l w a n in g , which

c h a r a c t e r i s e d t h e l e o r i a j . In t o r g l a c i a l s t a g e , sea l e v e r o s e .

As th e w a t e r s advanced headward a l o n g th e e n t r e n c h e d ' v a l l e y s

169

170

a s u b - s e a wave o f c o a r s e a l l u v i u m e x t e n d e d u p - v a l l e y a l o n g

t h e v a l l e y f l o o r . F i n a l l y a t i n e o f e q u i l i b r i u m was r e a c h e d

'./hen, duo p r i m a r i l y to t h e s l o w i n g down o f s e a l e v e l r i c e ,

a l l u v i a t i o n began t o keep pace w ith th e t r a n s g r e s s i n g w a t e r s .

The s h o r e l i n e no l o n g e r r e t r e a t e d . S u b s e q u e n t to t h i s t im e

t h e major s t r e a m s began t o b u i l d d e l t a s g u l fw a r d and b l a n k

e t e d the p r e v i o u s l y d e p o s i t e d c o a r s e m a t e r i a l i n th e t r o u g h s •

w i t h a l a y e r o f f i n e r a l l u v i u m . Seme o f t h e s t r e a m c o u rse

and d e l t a s h i f t s o f the M i s s i s s i p p i and Hed R i v e r s , d u r in g

t h i s t i m e , have been o u t l i n e d by F i s k ( 1 9 4 0 ) . As a r e s u l t

o f t h i s d e l t a i c e x p a n s io n oho s h o r e l i n e ad v a n ce d , i n some

a r e a s , t o p o s i t i o n s f u r g u l fw a r d o f i t s p r e s e n t l o c a t i o n .

The s e d i m e n t s , d e p o s i t e d d u r in g th e 1-soriax* i n t e r - g l a c i a l

s t a g e , fo rm in g what i s now k n o w n ' a s t h e i - r a i r i e f o r m a t i o n ,

has been s u b s e q u e n t l y downwnrped toward th e h a l f and up

l i f t e d i n l a n d .

With the l o w e r i n g o f s e a l e v e l d u r i n g th e i -a te W is

c o n s i n g l a c i a t i o n e n tre n c h m e n t o f s t r e a m s i n t o th e new ly

formed F r a i r i e s u r f a c e to o k p l a c e . A ga in g r e a t q u a n t i t i e s

o f c o a r s e sand and g r a v e l -were t r a n s p o r t e d beyond ti ie s h o r e

l i n e , w h ic h , due to tiie lov;ered s e a l e v e l , was l o c a t e d f a r

beyond thu ^ r e s e n t sh o re . S u b seq u en t c l i m a t i c a m e l i o r a t i o n

and g l a c i e r w an in g b ro u g h t ab o u t a n o t h e r r i s e in sea l e v e l ,

th e s t a r t o f which marks the b e g i n n in g o f tiie He c e n t e p o c h .

T h is e v e n t p r o b a b ly o c c u r r e d between 2 5 , 0 0 0 and 1 5 , 0 0 0 y e a r s

171

a g o . Accom panying t h i s r i s e o f s e a l e v e l was t h e i n e v i t a b l e

wave o i c o a r s e a l l u v i u m e x t e n d i n g u p - v a l l e y in t h e wake o f

t h e i n l a n d p r o j e c t i n g f i n g e r s o f water t h a t o c c u p i e d t h e v a l

l e y s p r e v i o u s l y c u t in t h e I r a i r i e s u r f a c e .

A p p r o x im a t e l y 5 , 0 0 b y e a r s ago a p o i n t was r e a c h e d

where the d e p o s i t i o n c o u l d k eep p a c e w i t h t h e s lo w e d down

r i s e in s e a l e v e l , and the s h o r e l i n e no l o n g e r r e t r e a t e d .

Whether t h e s e a l e v e l r e a c h e d t h i s - 5 , 0 0 0 y e a r p o s i t i o n

a f t e r a s t e a d y , g r a d u a l r i s e , a r i s e marked by s e v e r a l minor

f l u c t u a t i o n s , or i f t h i s p o s i t i o n was h i g h e r than modern sea

l e v e l a r e q u e s t i o n s s t i l l open t o d e b u t e . N e v e r t h e l e s s , th e

a v a i l a b l e e v i d e n c e seem s t o i n d i c a t e t h a t a p p r o x i m a t e l y 5 ,0 0 0

y e a r s ago d e l t a i c g r o w th began t o d i s p l a c e t h e w a t e r t h a t hod

e x t e n d e d up the i i i s s i s s i p p i A l l u v i a l V a l l e y , p o s s i b l y to th e

l a t i t u d e o f Baton R ouge . T h i s g u l f w a r d growth was accompan

i e d by many s h i f t s b o t h i n c o u r s e and l o c a t i o n o f the a c t i v e

d e l t a . Thus , a f r o n t o f f i n e a l l u v i u m was pushed g u l f w a r d

o v e r th e p r e v i o u s l y d e p o s i t e d s e d i m e n t s in t h e t r o u g h s ( c o n

s i s t i n g o f c o a r s e b a s a l f l u v i a t i l e d e p o s i t s , o v e r l a i n by

e s t u a r i n e and m arine s e d i m e n t s ) and t h e i n t e r - t r o u g h o l d e r

d e p o s i t s .

The f i r s t r e a d i l y d i s c e r n i b l e c o u r s e and d e l t a

in c e n t r a l c o a s t a l L o u i s i a n a i s t h a t o f t h e Bayou Gale*

s y s t e m . T h is s t r e a m p r o b a b l y came i n t o e x i s t e n c e a b o u t 600

17230B. C. V a r io u s p o r t i o n s o f th e S a l e 1 s y s t e m s e r v e d a s a

m ajor d i s t r i b u t a r y o r t h e main c h a n n e l o f t h e M i s s i s s i p p i

R iv e r from 500 t o 300 B . C. S u b seq u en t d i v e r s i o n o f f l o w ,

fo rm in g Bayou Cypremort and p o s s i b l y o t h e r d i s t r i b u t a r i e s e x

t e n d i n g e a s tw a r d i n t o t h e p r e s e n t Lake V e r r e t -T h ib o d a u x

r e g i o n , brough t ab o u t t h e g r a d u a l abandonment o f t h e s o u t h e r n

p o r t i o n s o f t h e S a l e ’ s y s t e m . S t i l l l a t e r , a b o u t 100 3 . C. ,

the Teche c o u r s e o f t h e M i s s i s s i p p i R i v e r was e s t a b l i s h e d .

The V e r m i l i o n R iv e r o r i g i n a t e d a s a d i s t r i b u t o r , ' / o f t h e

T e c h e - M i s s i s s i p p i . The T e c h e - n i s s i s s i p p i u t i l i z e d Bayous

C y p renort and S a l e ’ a s d i s t r i b u t a r y c h a n n e l s .

S u b s e q u e n t l y when t h e T e c h e - I a s s i s s i p p i c o u r se was

abandoned i n f a v o r o f t h e more e a s t e r n h'urly S t . Bernard

s u b - d e l t a c o u r s e s t h e Red R i v e r o c c u p ie d t h e abandoned chan

n e l s and u t i l i z e d t h e V e r m i l io n R iv e r a s a d i s t r i b u t a r y .

Bayous Cypremort and S a l e 1 d id n o t f u n c t i o n o s im p o r ta n t d i s

t r i b u t a r i e s o f t h e Red, b u t p r o b a b ly r e c e i v e d f l o o d f l o w .

During th e S a l e 1 , Cyprem ort, and T e c h e - A i i s s i s s i p p i

s t a g e s th e s h o r e l i n e i n ti ie e a s t e r n p o r t i o n o f the r e g i o n

The d a t e s p r e s e n t e d h e r e a re s p e c u l a t i v e . They a re b a s e d p r i m a r i l y upon t h e c u l t u r o l c h r o n o lo g y o f P h i l l i p s , F o rd , and G r i f f o n ( i y 5 1 ) > the r i v e r s e q u en ce d a t i n g o f F i s k ( 1 9 4 4 ) , and t h e w r i t e r ’ s p e r s o n a l o p i n i o n . The age sequ en ce o f t h e s t r e a m s , h o w ev er , i s v a l i d . The m ethods used in e s t a b l i s h i n g t h e r e l a t i v e a g e s have been f u l l y d i s c u s s e d i n th e r e p o i ’t and i t s h o u ld be p o i n t e d o u t t h a t t h e seq u en ce was d e f i n i t e l y n o t f o r m u l a t e d on the b a s i s o f c u l t u r a l e v i d e n c e a l o n e .

173

was l o c a t e d g u l f w a r d o f i t s xjr e s e n t p o s i t i o n . T h i s was n o t

the s i t u a t i o n i n V e n n i l i o n P a r i s h , h o w e v e r , where a r e l a

t i v e l y l a r g e embayment e x i s t e d , th e b o r d e r s o f w h ich a r e now

o u t l i n e d by o y s t e r s h e l l r i d g e s . The f i l l i n g i n o f a p o r t i o n

o f t h i s embayment, s u b s e q u e n t t o T e c h e - . i i s s i s s i p p i t i m e ,

makes i t p o s s i b l e t o j u d g e , i n u r t , th e v a l i d i t y o f p r o

p o s e d d e l t a i c s e q u e n c e s . A s l i g h t l y m o d i f i e d v e r s i o n o f th e

s e q u e n c e p r o p o s e d by M c l n t i r e ( 1 9 5 4 ) m o st c l o s e l y f i t s t h e

p a t t e r n d i c t a t e d by t h i s c h e n i e r com plex o f V e r m i l io n

P a r i s h .

At t h e p r e s e n t t im e most bay s h o r e l i n e s i n t h e a r e a

a r e r e t r e a t i n g ; h o w ev e r , t h e w a te r b o d i e s t h e m s e l v e s a re

c o n c o m i t a n t l y f i l l i n g i n . The g u l f s h o r e l i n e o f Harsh

I s l a n d i s r e t r e a t i n g , but not a t th e r a t e i n d i c a t e d by a

c o m p a r i s o n o f o l d e r c h a r t s . In o t h e r words t h i s r e t r e a t has

s lo w e d down and p r o b a b l y w i l l r e v e r s e in t h e n e a r f u t u r e .

T h is change from s h o r e l i n e r e t r e a t t o s h o r e l i n e a d v a n c e , h a s

a l r e a d y o c c u r r e d a l o n g m ost o f t h e g u l f s h o r e l i n e o f Ver

m i l i o n P a r i s h . In t h e C h e n ie r au T i g r e r e g i o n , f o r e x a m p le ,

wide m u d f l a t s , t h e i n n e r p o r t i o n s o f w h ich have been c o n

v e r t e d t o m arsh , have b u i l t g u l f w a r d w i t h i n t h e l a s t t e n

y e a r s . The p r o g r e s s i v e e n l a r g e m e n t o f the A t c h a f a l a y a R i v e r ,

a t t h e e x p e n s e o f t h e M i s s i s s i p p i , h a s b rou g h t a b o u t t h i s

r e c e n t i n f l u x o f s e d i m e n t . T h i s t r e n d w i l l u n d o u b te d ly be

m a i n t a i n e d and c o u l d be g r e a t l y a c c e l e r a t e d i f t h e p r e s e n t

174

r i s e o f s e a l e v e l n o t e d by l iar me r (1 9 4 9 and 1 9 5 2 ) c o n t i n u e s .

Man’ s i n t e r v e n t i o n w i l l be n e c e s s a r y i n o r d e r to. p r e v e n t th e

A t c h a f a l a y a from d i v e r t i n g t h e M i s s i s s i p p i and f o r m in g a

h u g e , g u l f w a r d e x p a n d in g d e l t a i n t h e A t c h a f a l a y a Bay r e g i o n .

The p r e c e d i n g summary b r i e f l y s t a t e s some o f t h e con

c l u s i o n s a r r i v e d a t i n t h i s work. These c o n c l u s i o n s , and

o t h e r s p r e v i o u s l y m e n t io n e d , a r e b a s e d on d a ta t h a t were

c o l l e c t e d by t h e w r i t e r o v e r a f o u r y e a r p e r i o d . The w r i t e r

f e e l s t h a t t h e c o n c l u s i o n s r e a c h e d f i t t h e a v a i l a b l e d a t a

m ost l o g i c a l l y , a l t h o u g h , a d m i t t e d l y , in a f e w c a s e s , d i f

f e r e n t h y p o t h e s e s c o u l d bo p r o p o s e d . A d d i t i o n a l f n c t u a l

i n f o r m a t i o n s h o u l d , by a l l m eans , be s o u g h t i n an a t t e m p t to

e i t h e r s t r e n g t h e n or d i s p r o v e many o f th e h y p o t h e s e s . Thus,

a s i s so o f t e n t h e c a s e i n g e o l o g i c p u r s u i t s , t h e end o f a

r e p o r t . i s in r e a l i t y t h e b e g i n n i n g o f th e work t o be d o n e .

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SELECTED BIBLIOGRAPHY

Ahlmann, Hans W. ( 1 9 5 2 ) , ’' G l a c i e r V a r i a t i o n s and C l i m a t i c F l u c t u a t i o n s , ” Bowman M em oria l L e c t u r e , American G e o g r a p h i c a l S o c i e t y , W a s h in g t o n , D. C . . A u g u s t 1 3 , 1952 ( l i t h o p r i n t r e p r o d u c t i o n o f . s p e e c h ) .

A l l e n , H. L. ( 1 8 4 7 ) , " V i s i t t o A t t a k a p a s , " ( f ro m t h e HewYork Am erican A g r i c u l t u r i s t ) , P l a n t e r s B a n n e r , V o l . X I I , Ho. 3 0 , J u l y 2 2 , 1 8 4 7 , F r a n k l i n , l a .

A n d r e a o s e n , C. L. ( 1 9 4 7 ) , " I n t e r n a l Im provem ents In L o u i s i a n a , " 1 8 2 4 - 1 S 3 7 , fLhe L o u i s i a n a H i s t o r i c a l Q u a r t e r l y , V o l . 3 0 , Ho. 1 , J a n u a r y , 1 9 4 7 .

A r r h e n i u s , G. ( 1 9 5 G ) , "Late C e n o z o ic C l i m a t i c Changes a sR ecorded hy t h e E q u a t o r i a l C u rren t S y s t e m ," T e l l u s , V o l . 2 , Ho. 2 , pp . 8 3 - 8 8 .

A r r h e n i u s , G. , l C j e l l b e r g , G . , and L ib b y , W. F. ( 1 9 5 1 ) , "Age D e t e r m i n a t i o n o f P a c i f i c Chalk Ooze by R a d io c a r b o n and T i ta n iu m C o n t e n t , " T e l l u s , V o l . 3 , Ho. 4 , Eovember, 1 9 5 1 , pp . 2 2 2 - 2 2 9 .

A t w a t e r , Gordon ( 1 9 5 1 ) , "The G e o lo g y o f t h e F i v e I s l a n d s , I b e r i a , and S t . Mary P a r i s h e s , L o u i s i a n a , " Paper p r e s e n t e d a t F i r s t Annual M e e t i n g o f G u l f C oast A s s o c i a t i o n o f G e o l o g i c a l S o c i e t i e s , Hew O r l e a n s ,Nov. 1 7 , 1 9 5 1 .

B a k k e r , J . P . ( 1 9 5 4 ) , "Uber den E i n f l u s s von K lim a, J u n g e r e r S e d i m e n t a t i o n und B o d e n p r o f i l e n t w i c k l u n g a u f d i e Savannen Hord-Surinoms," Erdkunde, Band V I I I , l i e f t 2 , A p r i l , 1 9 5 4 , P p . 8 9 - 1 1 2 .

B a l k , R o b e r t ( 1 9 4 9 ) , ’S t r u c t u r e o f Grand S a l i n e S a l t Dome,Van Zandt C o u n ty , T e x a s , " American A s s o c i a t i o n o f P e t r o l e u m G e o l o g i s t s , V o l . 3 3 , Ho. 1 1 , pp . 1 7 9 1 - 1 8 2 9 , 1 9 4 9 .

B a l k , R o b e r t ( 1 9 5 3 ) , " S a l t S t r u c t u r e o f J e f f e r s o n I s l a n dS a l t Dome, I b e r i a and V e r m i l io n P a i ' i s h e s , L o u i s i a n a , " Am erican A s s o c i a t i o n o f P 'etro leum G e o l o g i s t s , V o l .3 7 , No. 9 , 1 9 5 3 .

176

177

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F i s k , l i . N. ( 1 9 4 4 ) , " G e o l o g i c a l I n v e s t i g a t i o n o f t h e A l l u v i a l V a l l e y o f t h e Lower M i s s i s s i p p i R i v e r , " M i s s i s s i p p i R iv e r C om m iss ion , 1 9 4 4 .

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F i s k , K. N. ( 1 9 4 8 ) , " G e o l o g i c a l I n v e s t i g a t i o n o f the LowerM e m e n t a u B a s i n and A d j a c e n t A r e a s i n C o a s t a l L o u i s i a n a , " U n p u b l i s h e d r e p o r t , Departm ent o f t h e Army,Corps o f E n g i n e e r s , V i c k s b u r g , M i s s i s s i p p i , 1 9 4 8 .

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H a r r i s , W i l l i a m K. ( 1 8 8 1 ) , " L o u is ia n a P r o d u c t s , R e s o u r c e s and A t t r a c t i o i i s , w i t h a s k e t c h o f t h e P a r i s h e s , " S t a t e Com m iss ioner o f A g r i c u l t u r e and I m m i g r a t i o n , Lev/ O r l e a n s Democrat P r i n t , Hew O r l e a n s , 1 8 8 1 .

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H i l g a r d , Eugene V/. ( I S 6 9 ) , "A P r e l i m i n a r y R eport o f a Geol o g i c a l R e c o n n a i s s a n c e o f L o u i s i a n a , " DeBow’ s R e v iew , Septem ber , 1 8 6 9 , pp* 7 4 5 - 7 6 9 , Lev; O r l e a n s .

H i l g a r d , E. V/. ( 1 8 7 3 ) , "Supplem entary and F i n a l R eport o f a G e o l o g i c a l R e c o n n a i s s a n c e o f t h e S t a t e o f L o u i s i a n a , " New O r l e a n s , 1873 (S u rv e y co n d u cted d u r in g May and June o f I 8 6 9 .

H i l g a r d , E. W. ( 1 8 8 4 ) , " F h y s ic o - G e o g r a p h ic u l and A g r i c u l t u r a l F e a t u r e s o f L o u i s i a n a , " U n i t e d S t a t e s Tenth C e n su s , C o t to n P r o d u c t i o n , I t . 1 , 1 8 8 4 , W ash ington , pp. 1 1 0 - 1 7 5 .

H o l i e , C h a r le s G . , " S ed im e n ta t io n a t th e Mouth o f th e M i s s i s s i p p i R i v e r /'l-'roce*. d i n g s o f Second C o n fe r e n c e on C o a s t a l E n g i n e e r i n g , H o u s to n , T e x a s , November, 1 9 51 , C o u n c i l on Wave R e s e a r c h — The E n g i n e e r i n g F o u n d a t io n , B e r k e l e y , C a l i f o r n i a , 1 9 5 2 , pp. 1 1 1 - 1 2 9 .

H o l l i s t e r , A r c h ie 8 . ( 1 9 5 2 ) , "The Geography o f Cameron P ari s h , ” Buch P r i n t i n g Company, Septem ber , 1952.

H o p k in s , F . V, ( 1 8 7 1 ) , "Second Annual R eport o f t h e G e o l o g i c a l Su rv ey o f L o u i s i a n a , R eport o f 1870 ,11 New O r l e a n s , 1 87 1 .

Howe, F . V. and I,lore s i , C. K. (193-1) , "Geology o f I b e r i aP a r i s h , " S t a t e o f L o u i s i a n a , Department o f C on serva t i o n , Bureau o f S c i e n t i f i c R e s e a r c h o f t h e M in e r a l s D i v i s i o n , 1 9 3 1 , G e o l o g i c a l B u l l e t i n No. 1 .

Howe, H. V. and M o r e s i , C. K. ( 1 9 3 3 ) , "Geology o f L a f a y e t t e and S t . M a rt in P a r i s h e s , " G e o l o g i c a l B u l l e t i n No. 3 , L o u i s i a n a Department o f C o n s e r v a t i o n , 1933-

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Howe, II. V. and R u s s e l l , R. J . ( 1 9 3 5 ) , "R ep orts on t h e Geol o g y o f Caiaeron and V e r m i l io n P a r i s h e s , " G e o l o g i c a l B u l l e t i n No. 6 , D epartm ent o f C o n s e r v a t i o n , L o u i s i a n a G e o l o g i c a l S u r v e y , 1 9 3 5 .

Humphreys, C a p t . A . A. and A b b o t , L i e u t . H. L. ( 1 8 7 6 ) , Rep o r t on t h e I h y s i o s and H y d r a u l i c s o f th e M i s s i s s i p p i R i v e r , e t c . . P r o f e s s i o n u l Haper o f t h e Corps o f T o p o g r a p h i c a l E n g i n e e r s , N o . 4 , 1 8 6 i ( R e p r i n t 1 8 7 6 ) ; W a sh in g to n : Government P r i n t i n g O f f i c e .

J o n e s , Owen T. ( 1 9 4 4 ) , "The Compaction o f Liuddy S e d i m e n t s ," - i u a r t e r l y J o u r n u l o f G e o l o g i c a l S o c i e t y London ,V o l . 10b , P a r t s 1 and 2 , 1 9 4 4 , pp. 1 3 7 - 1 6 0 .

J o n e s , 1-aul H. , T u rcan , A. I i . , J r . , and S k i b i t z k e , H. E.( 1 9 5 4 ) , "G eology and Ground Viator R e s o u r c e s o f S o u t h w e s t e r n L o u i s i a n a , " G e o l o g i c a l B u l l e t i n No. 3 0 , Dep a r tm en t o f C o n s e r v a t i o n , L o u i s i a n a G e o l o g i c a l Surv e y , 1 9 5 4 .

K e s s e l i , John E. ( 1 9 4 1 ) , "The C oncept o f t h e Graded R i v e r , " J o u r n a l o f G e o lo g y , V o l . 4 9 , No. 6 , 1 9 4 1 , PP* 5 6 1 - 588 .

K im b le , George I:. f . ( 1 9 4 2 ) , ”'.;ind and Cave ," G e o g r a p h i c a l M a g a z in e , V o l . 1 5 , No. 2 , 1 9 1 2 , pp . 8 8 - 9 6 .

K i n d l e , E. K. ( 1 9 3 6 ) , " N o te s on S h a l lo w VVuter-Sand S t r u c t u r e s , " J o u r n a l o f G e o lo g y , V o l . 4 4 , No. 7 , 1 9 3 6 , pp. 8 6 1 - 8 6 9 .

K in g , C. A. i i . and G i l l i a m s , G. G. ( 1 9 4 9 ) , "The V e r n a t io nand Movement o f Sand Burs by Gave A c t i o n , " G e o g r a p h i c a l J o u r n a l , V o l . 1 1 3 , J a n u a r y - J u n e , 1 94 9 , pp . 7 8 - 8 5 .

K u i f f e n , E. B. and Lowe, H. V. ( 1 9 3 2 ) , " i h y s i o g r a p h i cH i s t o r y o f V e r m i l i o n R i v e r , L o u i s i a n a , " G e o l o g i c a l S o c i e t y o f A m e r ic a , B u l l e t i n , V o l . 4 3 , No. 1 , 1 9 3 2 , pp. 2 4 7 -2 4 8 ( a b s t r a c t ) .

Knox, A r th u r S . ( 1 9 4 8 ) , "The 1-eat D e p o s i t s o f Bermuda ana E v i d e n c e s o f P o s t - G l a c i a l Changes i n Sea L e y e i ^ ' J o u r n a l o f G e o lo g y , V o l . 4 8 , No. 7 , 1 9 4 0 , p p . 7 6 7 - 7 8 0 .

Krumbein, W. C. and C a l d w e l l , L. T. ( 1 9 3 9 ) , "A rea l V a r i a t i o n o f O rg a n ic Carbon C o n te n t o f B a r a t a r i a Bay S e d i m e n t s , L o u i s i a n a , " American A s s o c i a t i o n o f i e t r o l e u m G e o l o g i s t s , V o l . 2 3 , No. 4 , p p . 5 8 2 - 5 9 4 , 1 9 3 9 .

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IC ullenburg , 3 . ( 1 9 5 3 ) , " A b so lu te C h ro n o lo g y o f D eep -S e a S e d i m ents and th e D e p o s i t i o n o f C la y on t h e Ocean F l o o r , " T e l l u s , V o l . 5 , No. 3 , A u g u s t , 1 9 5 3 , pp . 3 0 2 - 3 0 5 .

Landry, S t u a r t 0 . ( 1 9 5 2 ) , L o u i s i u n a Almanac and F a c t B o o k - - 1 9 5 0 , 1 9 5 1 , S t u a r t 0 . Landry, e d i t o r , L o u i s i a n a Almanac and F a c t Book, I n c . , Few O r l e a n s , L a . , 1 9 5 2 .

L e B la n c , De Nux L. ( 1 9 4 1 ) , " C o n t r i b u t i o n s to t h e Geography o f t h e Lower T e c h e ," ( u n p u b l i s h e d L u s t e r ' s t h e s i s ) , L o u i s i a n a S t a t e U n i v e r s i t y , 1 9 4 1 .

L e B la n c , D u dley J . ( 1 9 3 2 ) , "The True S t o r y o f t h e A c a d i e n s , " L a f a y e t t e , 1 9 3 2 .

L e B l a n c , R. J . a n d B e r n a r d , II. A. ( 19 5 4 ) , "Resume o f J-ate R e c e n t G e o l o g i c a l h i s t o r y o f t h e G u l f C o a s t , " Geo- l o g i e en M i j n b ou w , V o l . 16 , P o . 6 , J u n e , 1 9 5 4 , p p . 1 8 5 - 1 9 5 .

L e i p p u r , Da l e F . ( 1 9 5 4 ) , " P h y s i c a l O c e a n o g r a p h y o f t h e G u l f o f M e x i c o , " G u l f o f M e x i c o , I t s O r i g i n , h a t e r s , and M a r i n e L i f e , F i s h e r y B u l l e t i n 8 9 , U n i t e d S t u t e s G o ve r nm e n t P r i n t i n g O f f i c e , W a s h i n g t o n , 1 9 5 4 , p p . 1 1 9 - 1 3 7 .

L e o p o ld , L. S . and Maduock, T . , J r . ( 1 9 5 3 ) , "The h y d r a u l i c Geometry o f S tream C h ann els and Some l - h y s i o g r a p h i c I m p l i c a t i o n s , " G e o l o g i c a l S u rv e y i r o f e s s i o n a l t a p e r 2 5 2 , U n i t e d S t a t e s Government P r i n t i n g O f f i c e , W a sh in g to n , 1953 .

L e o p o ld , Luna 13. and M i l l e r , John P . ( 1 9 5 4 ) , "A P o s t g l a c i a l C h ro n o log y f o r Some A l l u v i a l V a l l e y s in Wyoming," G e o l o g i c a l S u r v e y W a te r -S u p p ly P aper 1 2 6 1 , U n i t e d S t a t e s Government P r i n t i n g O f f i c e , W a sh in g to n , 1 9 5 4 .

L i p s e y , T. L. L. ( 1 9 1 8 ) , "A'ochafalaya R i v e r and Bayous C o u r t a b le a u , T e ch e , and V e r m i l i o n , L o u i s i a n a , "House Document # 1 2 3 0 , 6 5 th C o n g r e s s , 2nd s e s s i o n ,1918 ( S e r i a l h o . 7 3 4 9 ) .

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L o c k e t t , Samuel H. ( 1 8 7 3 ) , " L o u i s i a n a As I t I s , " 1873 (no o t h e r i n f o r m a t i o n ) .

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L o u i s i a n a D epartm ent o f P u b l i c ’.Yorks ( 1 9 4 2 ) , " I b e r i a P a r i s h , L o u i s i a n a , R e s o u r c e s and F a c i l i t i e s , " S t a t e o f L o u i s i a n a , D epartm ent o f P u b l i c Works, I b e r i a P a r i s h R e s o u r c e s P l a n n i n g Board i n c o o p e r a t i o n w i t h th e Rev/ I b e r i a Chamber o f Commerce, 194*2.

L o u i s i a n a D epartm en t o f P u b l i c '.Yorks ( 1 9 4 5 ) , " L a f a y e t t e i u r - i s h , L o u i s i a n a - - R e s o u r o e s and F a c i l i t i e s , " S t a t e D epartm en t o f P u b l i c VYorks and L a f a y e t t e P a r i s h P l a n n i n g B oard , 1 9 45 .

L o u i s i a n a Departm ent o f P u b l i c Works ( 1 9 4 6 ) , " V e r m i l io n P a r i s h R e s o u r c e s and F a c i l i t i e s , " S t a t e Departm ent o f P u b l i c Works and V e r m i l i o n P a r i s h P l a n n i n g B oard ,1946 .

L o u i s i a n a Departm ent o f P u b l i c Yorks ( 1 9 4 8 ) , " L o u i s i a n a ' s C o a s t a l Highway and Why I t Sh ou ld Be B u i l t , " i n C o o p e r a t i o n w i t h Cameron P a r i s h P l a n n i n g Board and V e r m i l io n P a r i s h P l a n n i n g Board, Hay, 1 9 4 8 .

L o u i s i a n a Departm ent o f P u b l i c Works ( 1 9 1 8 ? ) , " I b e r i a 1 a r - i s h , L o u i s i a n a - - R e s o u r c e s and F a c i l i t i e s , " S t a t e D epartm en t o f P u b l i c ’.Yorks and I b e r i a P a r i s h D e v e l opment B o a rd , 1 9 4 8 ? .

L o u i s i a n a De. a r tm e n t o f P u b l i c Works ( 1 9 4 9 ) , " S t . MaryP a r i s h , L o u i s i a n a — R e s o u r c e s and F a c i l i t i e s , " S t a t e D epartm en t o f P u b l i c Works and S t . Mars’- P a r i s h P l a n n i n g B o a r d , 1 9 4 9 .

L o u i s i a n a Departm ent o f P u b l i c -.Yorks ( 1 9 5 0 ) , " S t . M a r t inP a r i s h , L o u i s i a n a — R e s o u r c e s and F a c i l i t i e s , " S t a t e Departm ent o f P u b l i c VYorks and S t , M a r t in P a r i s h P l a n n i n g B oard , 1 9 5 0 .

L o u i s i a n a Department o f Commerce and I n d u s t r y ( 1 9 5 0 ? ) , "Lund o f E v a n g e l i n e — Home o f t h e A c a d i a n s - - P a t h o f t h e T e c h e ," P u b l i s h e d by T o u r i s t B u re a u , Departm ent o f Commerce and I n d u s t r y , B aton R ouge , L a . , 195C ( ? ) ,

L o u i s i a n a F lo o d C o n t r o l and ',,'atcr C o n s e r v a t i o n Co m i s s i o n ( 1 9 3 8 ) , "Report o f the L o u i s i a n a F lo o d C o n t r o l and Water C o n s e r v a t i o n C om m iss io n ," ( fr o m December 1 8 , 1936 t o May 1 , 1 .938) , L o u i s i a n a F lo o d C o n t r o l and Water C o n s e r v a t i o n Com m iss ion , B aton Rouge , 1 9 3 8 .

L o u i s i a n a , L e g i s l a t i v e Documents o f ( 1 8 5 2 ) , "Report o f t h e S t a t e E n g in e e r f o r 18 5 1 , ” B aton R o u g e , 1 8 5 2 .

L o u i s i a n a , L e g i s l a t i v u Documents o f ( I 8 6 0 ) , "Annual R e p o r t o f t h e Board o f Swamp Land C o m m iss io n e r s ( f o r 1 8 5 9 ) , ” B a to n Rouge , I 8 6 0 .

L o u i s i a n a , L e g i s l a t i v e Documents o f ( 1 8 7 3 ) , ’’R e p o r t o f th e S t a t e E n g i n e e r s , " 1 873 .

L o u i s i a n a , S t a t e U n i v e r s i t y Departm ent o f A r c h i v e s and Manu s c r i p t s ( 1 9 2 6 ) , P h a r r (John U. and F a m i ly ) t a p e r s — 1 8 4 8 - 1 9 2 6 ( t y p e w r i t t e n copy o f o r i g i n a l t r a n s c r i b e d by John P h a r r , J r . in 1 9 2 6 , L o u i s i a n a S t a t e U n i v e r s i t y Departm ent o f A r c h i v e s and M a n u s c r i p t s .

L o u i s i a n a S t a t e U n i v e r s i t y Departm ent o f A r c h i v e s and Manu s c r i p t s ( 1 9 3 8 ) , I n v e n t o r y o f P a r i s h A r c h i v e s o f L o u i s i a n a , P r e p a r e d by t h e H i s t o r i c a l R e c o r d s S u r v e y D i v i s i o n o f '..’omen’ s and P r o f e s s i o n a l P r o j e c t s , V/orks P r o g r e s s A d m i n i s t r a t i o n , Ho. 2 8 , L a f a y e t t e P a r i s h ( L a f a y e t t e ) , L o u i s i a n a S t a t e U n i v e r s i t y , Vhe D epartm ent o f a r c h i v e s M a n u s c r i p t s , F e b r u a r y , 1 9 3 8 .

L o u i s i a n a , S u r v e y o f F e d e r a l A r c h i v e s i n ( 1 9 3 9 - 4 1 ) , " P in ta d o F a p e r s - - C o p i e s o f t h e a n c i e n t s u r v e y o r s p l a t s c o m p l e t e w i t h t r a n s l a t i o n o f o r i g i n a l n o t e s f r o m French and S p a n i s h , " Books I , I I I , and IV ( 1 8 0 1 - 1 8 0 4 ) , 1 9 3 9 - 1 9 4 1 .

L y e1 1 , C h a r l e s ( I 0 8 9 ) , P r i n c i p l e s o f G e o l o g y . ( 1 1 E d . , Hew Y o rk , A p p le to n and C o . , I 8 8 9 T, V o l . 1 , p p . 4 4 0 - 4 4 1 .

McCloy, S h e l b y T. ( 1 9 3 8 ) , "French C h a r i t i e s t o t h e A c a d i - a n s ," R e p o r t o f th e L o u i s i a n a H i s t o r i c a l Q u a r t e r l y , V o l . 2 1 , Ho. 3 , J u l y , 19 3 8 .

M c l n t i r e , V/m. G. ( 1 9 5 4 ) , " C o r r e l a t i o n o f l r e h i s t o r i c S e t t l merits and D e l t a D e v e lo p m e n t ," T e c h n i c a l R e p o r t Ho. T r a f f i c a b i l i t y and n a v i g a b i l i t y o f D e l t a - T y p e C o a s t s , I r o j e c t Ho. H7, onr 3 5 6 0 8 , Task Order Ho.UR 388 0 0 2 , o f t h e O f f i c e o f U a v a l R e s e a r c h , Baton Rouge, L o u i s i a n a , 1954 .

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M a c N e i l , F . S . ( 1 9 5 0 ) , " P l e i s t o c e n e S h o r e l i n e s i n F l o r i d a and G e o r g i a , " U n i t e d S t a t e s G e o l o g i c a l S u rv e y P r o l ' e s s i o n a l P ap e r 2 2 1 - F , U n i t e d S t a t e s Government P r i n t i n g O f f i c e , Y/a sh i n g t o n , 19 5 0 .

Mann, C h a r l e s 1 . , and K o l b e , Lawrence A. ( 1 9 1 2 ) , " S o i l Su rvey o f I b e r i a P a r i s h , L o u i s i u n a , " Government P r i n t i n g O f f i c e , W a s h in g t o n , 1 9 1 2 .

Mariner, K. A. ( 1 9 4 9 ) , "Sea L e v e l Changes A lo n g t h e C o a s t s o f t h e U n i t e d S t a t e s i n R e c e n t Y e a r s , " T r a n s . A u er . G e o p h y s i c a l U n io n , V o l . 3 0 , h o . 2 , 1 9 4 9 , PP* 2 0 1 - 2 0 4 .

Marmer, E. A. ( 1 9 3 2 ) , "Changes i n S e a - L e v e l D e term in ed from T id e O b s e r v a t i o n s , " P r o c . 2nd C o n f . on C o a s t a l E n g i n e e r i n g , C h a p t . 6 . pp . 6 2 - 6 7 , U n i v e r s i t y o f C a l i f o r n i a , B e r k e l e y , 1 9 5 2 .

M a t t l i e s , F. E . ( 1 9 4 0 ) , "Report o f Committee on G l a c i e r s , 1 9 3 9 - 4 0 , " A u er . G e o p h y s i c a l U n io n , T r a n s a c t i o n s o f 1 9 4 0 , P a r t I I , p p . 3 9 6 - 4 0 6 .

M a t t h e s , F . E . ( 1 9 4 6 ) , " u cp o r t o f Committee on G l a c i e r s , 1 9 4 5 , ” T r a n s . A u e r . G e o p h y s i c a l U n io n , V o l . 2 7 , l lo . 2 , 1 9 4 6 , p p . 2 1 9 - 2 3 3 .

I . l a t t h e s , G. K. ( 1 9 4 1 ) , " B a s ic A s p e c t s o f Stream m e a n d e r s ," T r a n s . A u er . G e o p h y s i c a l U n io n , A u g u s t , 1 9 4 1 , pp . 6 3 2 - 6 3 7 .

M eyer , A. I I . , and L e n a r i c k s o n , D. II. ( 1 9 1 9 ) , " S o i l Surveyo f S t . M a rt in P a r i s h , l a . , " U n i t e d S t a t e s Departm ent o f A g r i c u l t u r e , Bureau o f S o i l s R e p o r t , 1 91 9 , map.

M eyer, A. I.'., and K ir k , K. M. ( 1 9 1 6 ) , " S o i l S u rv e y o f L a f a y e t t e P a r i s h , L o u i s i a n a , " B u l l e t i n o f th e U n i t e d S t a t e s Departm ent o f A g r i c u l t u r e , 1 9 1 6 , map.

M eyer , W i l l i s G. ( 1 9 4 4 ) , "Grabens i n G u l f C o a s t A n t i c l i n e s and t h e i r R e l a t i o n t o O ther F a u l t e d T r o u g h s ," Am erican A s s o c i a t i o n o f l e t r o l e u m G e o l o g i s t s V o l . 28 ,Mo. 4 , pp . 5 4 1 - 5 5 3 , 1 9 4 4 .

M o n c r i e f , J . E . , and E a s t e r l y , I . D. ( 1 9 5 3 ) , "Recharge S t u d i e s i n t h e V e r m i l io n I i i v e r A r e a . " U n p u b l i sh e d pap er b a s e d 011 i n f o r m a t i o n o b t a i n e d in i n v e s t i g a t i o n s o f th e g r o u n d -v .n te r r e s o u r c e s o f L o u i s i a n a by th e G e o l o g i c a l S u r v e y , U n i t e d S t a t e s Departm ent o f t h e I n t e r i o r , in c o o p e r a t i o n w i t h t h e L o u i s i a n a G e o l o g i c a l S u r v e y , D epartm ent o f C o n s e r v a t i o n , Baton R ouge , 1 9 5 3 .

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AUTOBIOGRAPHY

J a c k H. Van L op ik was born i n H o l l a n d , M ic h ig a n i n

1 9 2 9 . H is e l e m e n t a r y , s e c o n d a r y , and h i g h s c h o o l e d u c a t i o n

was o b t a i n e d i n th e p u b l i c s c h o o l s o f Grand Haven, M ic h ig a n .

Upon g r a d u a t i o n from h i g h s c h o o l i n 19^6 he e n r o l l e d a t

M ic h ig a n S t a t e C o l l e g e and r e c e i v e d a B. S . d e g r e e i n G e o lo g y

from t h i s u n i v e r s i t y in 195D. A M. 3 . d e g r e e in G e o lo g y was

g r a n t e d by L o u i s i a n a S t a t e U n i v e r s i t y i n 1 9 5 3 . D uring t h e

i n t e r v a l s p e n t a t L o u i s i a n a S t a t e U n i v e r s i t y he s e r v e d a s a

d i s t r i c t i n v e s t i g a t o r on an O f f i c e o f L a v a l R e s e a r c h p r o j e c t

c o n c e r n e d w i t h t r a f f i n a b i l i t y and n a v i g a b i l i t y o f L o u i s ia n a

c o a s t a l m a r s h l a n d s .

At th e p r e s e n t t im e he i s c o n d u c t i n g r e s e a r c h , a t

L o u i s i a n a S t a t e U n i v e r s i t y , f o r th e Waterways E x p e r im e n t

S t a t i o n , U. S. Army Corps o f E n g i n e e r s , V i c k s b u r g , M i s s i s

s i p p i .