Geologic Considerations in Conservation

PlanningPart 2

Southern California Geology

(12/02)

http://www.geol.ucsb.edu/Outreach/Download/Freeware-FR.html

Geology of Southern California

San Andreas Garlock

San Jacinto

Elsinore

Imperial

Eastern

CA Shear

Zone

Landers6/28/92 Mw 7.3

The“Big Bend”

San Andreas Garlock

San Jacinto

Elsinore

Imperial

Eastern

CA Shear

Zone

Ventura

San Cayetano

San FernandoHollywood/Raymond

Cucamonga

Northridge1/17/94 Mw 6.7

Transverse Ranges

Mojave

Colorado Desert

Peninsular Ranges

Los Angeles Basin

Pint

o

Eagle

Little

San

Berna

rdin

o

San

Bern

ardi

no

San

Gab

riel

Santa

MonicaChan

nel

Isles

Santa

Ynez

Piru

Pine

Topatopa I-5/G

rape

vine

Cajo

n Pa

ss

San

Gorgo

nio

Pass

Rifting, Rotation, and Volcanism in the Western Transverse Ranges

Rifting, Rotation, and Volcanism in the Western Transverse Ranges

Rifting, Rotation, and Volcanism in the Western Transverse Ranges

Los Angeles Basin5 million years ago

Sharp, 1994

Santa Monica/Hollywood/Raymond

Sierra Madre/Cucamonga F.Z.

Whittier

Chino

Palos Verdes Hills

Newport-Inglewood

El Moreno

San Jose

Anticline

LAW

POSM

SG

SA

LB

Syncline

San FelipeHills

Agua Tibia

SanJacinto

Santa Rosa

San Timoteo

BorregoValley

AnzaUpland

SantaAna

Laguna

SantaMargarita

Cuyamaca SD

OE

F

El

R

SJ

V

M

P

Br

29

Bk

N

A

Tehachapi/

So. Sierra

Neva

da

San GabrielsSan Bernardino Little S.B./Pinto Whipple

Turtle

El Paso

ArgusSlate Avawatz

Providence

OldWoman

Old DadG

G

G

GBullion

Cady

Bristol

San Andreas

Garloc

k

Pinto Mtn

Eastern

CA Shear

Zone

Cima Volcanic Dome(330-480 years old)

Cima Volcanics(330-480 years old)

Alluvial Fan, Death Valley

Sand Dunes

• Occur in both deserts• Various types of sand

dunes are present• Found in valleys• Some have unique

acoustic properties

Fish Cr.

SantaRosa

Superstition

Vallecito

Coyote

McCoyWash

CargoMuchacho

Eagle

Cockscomb PalenIndioHills

EC

I

N

BOrocopaChuckawallaChocolate

East Mesa

Palo Verde

EC

I

N

B

San Gorgonio Pass/No. & So. Branches San Andreas

Sand Hills ?

Elsinore/Laguna Salada

San Jacinto/Coyote Cr./SuperstitionHills/Imperial

Elmore Ranch/ Brawley

Badlands

• Relatively rare for California

• Carrizo and Indio Hills

• Sculpted by infrequent flash floods

• Sparsely Vegetated

Salton Sea History• Periodic Holocene inundation

(beach ridges)• Lake Cahuilla 700 A.D. to

approx. 300 years ago.• 1824-1904: Inundation at least

8 times;• 1905: Accidental diversion of

Colorado River through Irrigation Canals (1907 closure)

• Agricultural runoff maintains present lake levels

Algodones Dunes

• Built by Colorado River sediments and erosion of bordering ranges

• 320 square miles• Moving southeast due to prevailing

winds (6-12 in/yr)