geography 101 part 3

8/13/2019 Geography 101 Part 3

1/29

Earth Materials and The Lithosphere(Christopherson Cha. 8)

I. Geologic Time

A. Age of the Earth: approx. 4.6 billion yearsB. Geologic Time Scale

Two EOS in Geologic Time!recambrian "46## $ %4&mya $ stan's for million years ago(!hanero)oic "%4& $ present(

Three E*AS of the !hanero)oic Eon!aleo)oic "%+# $ &%,mya(-eso)oic "&%, $ 66mya(eno)oic "6%.% $ present(

Two !E*/O0S of the eno)oic EraTertiary "6%.% 1 ,.2 mya(

3aternary ",.2 $ present(

Two E!O5S of the 3aternary !erio'!leistocene ",.2mya $ ,####ya(5olocene ",####ya $ present(

C. 7niformitarianism: "the present is the 8ey to the past( This is the assmption that the processeswhich we obser9e to'ay ha9e been operating throghot geologic time.

II. The Structure o the EarthA. General

!. *a'is: 64##8m

". 0ensity: 0ecreases from core to srface

#. Temperatre: ###; to 66%#; estimate' at core

B. ross$Sectional


2/29

. ritical Strctral Sb'i9isions

,. ?ithosphere "incl'es rst an' 7pper -antle(: This is the brittle oter layer of theearth. This is the layer bro8en into >lithospheric plates>.

&. Asthenosphere: This is the hot plastic layer of the mantle @st below the lithosphere.

III. Composition o Crust

A. Elements

Oxygen "O( %# Balcim "a( $4Silica "Si( &% BSo'im "a( &$Alminm "Al( 2 B!otassim "C( &$/ron "De( % B-agnesim "-g( &$

metals Bimportant plant ntrients

B. -inerals: /norganic chemical compon's their formation is affecte' by a9ailable elements heatpressre time. An assemblage of minerals in a soli' state is a roc8.

I%. &oc' Classiications lassifie' by the processes which forme' them.

/gneos: *oc8 forme' from molten material in the earths core.Se'imentary: *oc8 forme' from layere' accmlations roc8 particles or minerals.-etamorphic: *oc8 forme' from exposre to extreme heat an' pressre.

A. /gneos *oc8s: Dorme' from molten material in the earths core. They are classifie' in two'ifferent ways mineral type an' cooling en9ironment.

!. /gneos -ineral Types: ommonly contain silicate minerals "Si an' O combine'(. Thereare two main mineral types felsic an' mafic.

a) Delsic -inerals: "felfor fel'spar sicfor silica(. haracteri)e' by their light coloran' low 'ensity.

EFA-!?ES

3art) $ "SiO&( extremely common stable non$reacti9e.

!otassim Del'spar $ Silicates of Al an' C

So'im Del'spar $ Silicates of Al an' a

alcim Del'spar $ Silicates of Al an' a


3/29

$) -afic -inerals: "mafor magnesim ficfor ferric(. haracteri)e' by their 'ar8color an' high 'ensity.

EFA-!?ES

-icaAmphibole

!yroxene

Silicates of Al -g De C or a.

Oli9ine "ltramafic( -g an' De "low in silica(

". /gneos ooling En9ironments: /ntrsi9e "beneath the earth( or Extrsi9e "abo9e theearth(

A. /ntrsi9e: oole' beneath thesrface

. Extrsi9e: oole' abo9e the srface

,. ooling is S?OH beneath the EarthssrfaceI ths the minerals ha9e time togrow into large crystal forms.

,. ooling is *A!/0 at the EarthssrfaceI ths the minerals 0O OTha9e time to grow into large crystalforms.

&. The crystals are often 9isible to thena8e' eye

&. The crystals are generally OT9isible to the na8e' eye

. The roc8 appears coarse graine'"comprise' of larger particles li8e the

crystals mentione' abo9e(

. The roc8 appears fine graine'"comprise' of in'i9i'al particles

generally too small to see(

#. /gneos *oc8 Examples

-ineral Type /ntrsi9e Examples Extrsi9e ExamplesDelsic Granite *hyolite

Delsic "ten'ing towar' -afic( 0iorite An'esite

-afic Gabbro asalt

7ltramafic !eri'otite 0oesnt exist


4/29

B. Se'imentary *oc8s "?ithification(: Dorme' from roc8 fragments or mineral particles "calle'se'iment( are ero'e' transporte' an' 'eposite'. They may sit for thosan's or millions ofyears 'ring which time they n'ergo compaction an' cementation "a process where thefragments are pac8e' 'own an' cemente' together(. ollecti9ely this is calle' lithification.

!. lastic: Dorme' when fragments of pre$existing roc8 collect in one place.

a) onglomerate: Dorme' from cobbles an' pebbles mixe' with finer se'iments

$) San'stone: Dorme' from san' grains "li8e at the beach(

c) Siltstone: Dorme' from silt particles "possibly from a hge floo'ing ri9er(

d) Shale: Dorme' from clay particles that collect an' form a roc8 with 'istinctlayers

". hemical : Dorme' when 'issol9e' minerals precipitate from a soltion an' collect.!rocess sally happens in the ocean.

a) ?imestone: alcim arbonate aO

$) 0olomite: alcim an' -agnesim arbonates

#. Organic: Dorme' when 'ea' plant material collects in wet 9egetate' en9ironments an'becomes co9ere' with other se'iments "incl'es peat an' coalI natral gas is abypro'ct(

C. -etamorphic *oc8s: Any roc8 which has been expose' to extreme heat an' pressre beneaththe srface of the Earth.

!. Examples

a) Slate: Hhen shale is expose' to extreme heat an' pressre forming roc8 thatsplits into har' flat plates.

$) -arble: ?imestone which is expose' to heat an' pressre

c) Gneiss: *efers to most coarse graine' roc8s which become expose' to extremeheat an' pressre "granite conglomerate(


5/29

late Tectonics(Christopherson Cha. 8)

I. E*olution o the Theor+ o late Tectonics

A. Dirst Sggeste': ontinental fit note' as long ago as ,%=6. "Ortelis(. Sggeste' by otherscientists

B. Alfre' Hegener "Dather of ontinental 0rift J !late Tectonics(: German geophysicist an'meteorologist pblicly annonce' his theory in ,=,&. onsi'ere' re9oltionary.

!. Similar plants". Similar roc8s#. ontinental fit"ot sfficient proof for scientists(

C. !angaea "split in the TriassicI approx. &&%mya(: Hegeners original spercontinent split into thetwo following continents.

!. ?arasia: E9entally became . America Erope an' Asia.

". Gon'wana: E9entally became S. America Africa Astralia an' Antarctica.

,. ontine' -o9ement "the case of earthKa8es(: The continents "lithosphere( in constantmotion. The lithospheric plates mo9e at a rate of %$,#cmJyear "%#$,##8mJone million years(.onstantly e9ol9ing.

II. Modern Theor+ Too8 shape in the ,=6#s.

A. ritical Strctres!. ?ithosphere "rst L 7ppermost mantle(: re9iew earlier 'escription

". Asthenosphere: re9iew earlier 'escription

B. ritical !rocesses!. Sea Dloor Sprea'ing: Hhere sea floor sprea's apart an' new material comes to the

srface. Accretion is the a''ition of new crst material.

". Sb'ction: Hhere one plate 'i9es beneath another an' is consme'. onsmption isthe sbtraction of plate material.

III. Modern late Boundaries (Mechanisms and rocesses) There are three types of plate bon'ariesI'i9ergent con9ergent an' transform.

A. 0i9ergent on'aries "forces of extension(: Two plates are mo9ing away from each other an'magma is rising to the srface creating new plate material by accretion. There are two types.

!. Sea$Dloor Sprea'ing: -olten material rises to srface casing sea floor to sprea'.-olten material then fills the gap.

-i'$ocean ri'ge: -agma rises to the srface an' creates a blge.

-i'$ocean rift: The actal brea8 in the sea floor.

7n'ersea 9olcanic acti9ity: ?a9a extr'es into the sea creating new crst"accretion(.


6/29

Sea Dloor Sprea'ing

Examples: -i' Atlantic *i'ge The *e' Sea

". ontinental Sprea'ing "continental rptre(: Hhen molten material rises beneath acontinent casing it to split apart. This forms rift 9alleys on lan'. -olten material thenfills the gap "creating 9olcanoes(.

Examples: East African *ift


7/29


8/29

%olcanic and Tectonic rocesses and Landorms(The Building rocesses)(Christopherson Cha. -)

I. Introduction and &e*ieA. ?an'forms: Deatres on the srface of the lan' "montains 9alleys plains beaches etc(

. Geomorphology: Geomorphology is the st'y of the history an' processes which shape

lan'forms.

. Exogenic an' En'ogenic !rocesses: En'ogenic processes are 'ri9en from within the Earth "byEarths internal heat( an' exogenic processes are 'ri9en by forces at the Earths srface.

//. Crustal ,eormation rocesses As a reslt of !late Tectonics the lithosphere is n'er constant stress"compression extension shearing stresses(. This stress manifests itself in theee main ways

A. roa' Harping: The ben'ing of the crst o9er a large area. 7sally accomplishe' by isostaticrebon' where the crst rises in response to a weight being lifte' from it. This is common whenlarge ice sheets ha9e melte'. The crst will actally rebon'. This can also be case by therising of a large bo'y of magma.

. Dol'ing "compressional forces(: Se'imentary strata when compresse' will be bent into a seriesof wa9e li8e featres. The wa9e crests are anticlines an' the troghs are synclines.

/olding

. Dalting:Dalts are planar fractres "falt plane( in the Earths crst along which slippage "earthKa8e(occrs. They ta8e many forms.Don' commonly at plate bon'ariesI bt also elsewhere.


9/29

i. ormal Dalt "tensional forces(: *eslts in 9ertical mo9ement of lan'.Dalt Scarp is a cliff forme' by falting.

ormal Dalt

ormal Dalts in a Series "Graben an' 5orst(

ii. Stri8e$Slip "shearing forces(: *eslts in si'e to si'e hori)ontal mo9ement. ?ea9es a falttrace possibly a slight scarp. an form an offset stream.

*ight ?ateral Stri8e$Slip Dalt "top9iew( ?eft ?ateral Stri8e$Slip Dalt "top9iew("with offset stream(


10/29

iii. *e9erse Dalt "compressional forces(: *eslts in 9ertical mo9ement of lan'. aseso9ersteepening an' sbseKently lan'sli'es.

*e9erse Dalt

,. A special case of re9erse falt is calle' a thrst falt sally reser9e' for 9ery

low$angle thrsts sch as the orthri'ge A Ka8e. Any type of re9erse or thrstfalt in'icates compressional forces.

O9er$steepene' Dalt Scarp"lan'sli'es freKent(


11/29

///. Earth0ua'es S''en slippage along a falt occr at all types of plate bon'aries

A. Elastic *ebon' Theory:

,. 5elps to explain mo9ement along falts.&. Dalt ?oc8: Energy store' as stress bil's p.. Stress excee's friction reslting in s''en brea8 at the falt.

. General Terminology

i. Seismic Ha9es: *ipples of energy which pass throgh the crst.

ii. Docs: The sbsrface point where the maximm energy is release' "ie where theactal brea8 occrs(.

iii. Epicenter: The point on the srface 'irectly abo9e the focs.

. -easring /ntensity an' -agnit'e

i. -ercalli Scale "measres intensity(: Arbitrary scale "/$F//( which rates 'amage to terrainan' strctres.

ii. Seismograph: -easres 9ibrations case' by an earthKa8e.

iii. -oment -agnit'e Scale: 3antitati9e scale of the energy release'. *epresents thep'ate' 9ersion of the ol' *ichter Scale.

0. San An'reas Dalt: Transform bon'ary between !acific an' orth American !lates.

i. Dalt System: /ncl'es many relate' falts.

ii. Type of Dalt: *ight ?ateral Stri8e Slip Dalt

iii. E9oltion: 7ntil abot ,%$#mya there was a sb'ction )one on the west coast oforth America. -ch of the western 7nite' States is ma'e of crst which was >scrape'>onto the orth American !late. E9entally this bon'ary e9ol9e' into a transform typeof bon'ary.

III. %olcanism 1 rocesses and Landorms

A. ?ocations of Acti9ity

i. on9ergent !late on'aries: Hhere sb'ction occrs

ii. 0i9ergent on'aries: Sea Dloor sprea'ing centers or continental rptres.

iii. 5ot Spots: ase' by a single stationary mantle plme. See below


12/29

B. Two -a@or Types of


13/29

Docs on 5ot Spots: 5ot spots represent a single point of 9olcanic acti9ity.

This is referre' to as a >stationary mantle plme>

This type of acti9ity has helpe' scientists 'etermine the spee' of plate mo9ement. As a plate mo9es across a hot spot a chain of islan's is forme' "the 5awaiian /slan's is a great

example(.

The yongest islan' is o9er the crrent hot spot location while the ol'er islan's ha9e since mo9e'away from the acti9ity.

&2BLEM"see Digre 2.,=(: 5ow fast "in centimeters per year( is the !acific !late mo9ing o9er the5awaiian 5otspot To figre this ot 'etermine the 'istance from the crrent hot spot location "in8ilometers( to the islan' of -i'way. Since the age of -i'way islan' is abot &% million years followthis formla to calclate the rate:

P 'istance from hot spot "8m( Q x P ,##### cmJ8m Q J P age of islan' "yrs( Q R cmJyr

C.Explosi9e erptions can also case...........,. nue ardent"glowing a9alanche(: This is a clo' of searing hot aci'ic gas an' ash whichtra9els li8e a shoc8 wa9e 'own slope brning e9erything in its path.

&. lahar: -' an' 'ebris flow which reslts from the rapi' melting of ice an' snow 'ring anerption. ompose' of 9olcanic ash water m' an' se'iment of all si)es.

,. Other Deatres of


14/29

3eathering and Mass Mo*ement(Christopherson Cha. !4)

I. Introduction He ha9e pre9iosly loo8e' at the processes which bil' montains "orogenisis resltingform the en'ogenic processes(. He will now begin to loo8 at the collecti9e processes which 'en'e ortear 'own those montains "throgh exogenic processes(.

A. Two


15/29

!. Drost Action: The expansion of ice as it free)es generates a strong force capable offractring an' plc8ing small particles from coarse graine' roc8. This occrs when waterenters pore spaces between the grains an' repeate'ly free)es an' thaws. This canhappen on a larger scale as water collects in crac8s in the roc8. /n high montainen9ironments @agge' roc8s fractre' loose from cliffs collect in piles at the base. Theseare 8nown as tals slopes.

Drost Action

". rystalli)ation "Salt$rystal Growth(: The formation of crystals "salts other minerals(creates a we'ging action in the pore spaces of grainy roc8 "li8e san'stone(. As thecrystal lattice forms it we'ges loose grains. This happens especially in ari'en9ironments where water "with salts in soltion( flows throgh roc8 often flowing fromthe si'es of cliffs. The water e9aporates when it comes into contact with otsi'e airlea9ing behin' the salts to form crystals. This reslts in large arches at the base of cliffs.

#. !ressre *elease Mointing

a) 0eep roc8 n'er pressre: *oc8 at 'epth "pltons of granite metamorphic roc8etc( is slightly compacte' n'er the pressre of the o9erlying roc8.

$) *oof roc8 ero'e': As the roof roc8 is ero'e' away an' the n'erlying roc8 isnco9ere' it expan's slightly as the weight is release'.

c) !ressre release @oints form: Sheets of roc8 slip off in a process calle' sheetingor exfoliation "creates exfoliation 'omes(.

5. Temperatre Expansion N ontraction: Expansion an' contraction following the 'ailycycle of temperatre

6. !lant *oots: !lant roots grow into crac8s an' pry apart roc8s

7. 5y'ration: Expansion 'e to absorption of water


16/29

!ressre *elease Mointing

B. hemical Heathering !rocesses: The chemical alteration of roc8 minerals throgh exposre towater an' atmosphere. 3art) is the most resistant mineral when it comes to chemical

weathering.

!. Oxi'ation an' 5y'rolysis: This is the chemical nion of oxygen an' water respecti9elywith minerals to form other more stable minerals. Oxygen in particlar combines withmetallic elements. "Oxi'i)e' iron is rst.... De L O& R /ron oxi'e( This process reslts inthe brea8'own of the original roc8.

". arbonation "creates 8arst topography(: O& an' 5&O combine to form a wea8concentration of carbonic aci' "5&O( which is capable of 'issol9ing limestone"aO( into soltion. Hhere water rns throgh @oints in limestone ca9es can beforme'. This can also for 8arst topography.

#. Organic Aci's: !lants can pro'ce aci's which also ai' in the chemical brea8'own ofminerals.

C. EFA-!?E$$ Spheroi'al Heathering: Hhere roc8s ha9e been expose' to the elements for a longtime they begin to ta8e on a ron'e' "spheroi'al( shape. This is becase non$ron'e' roc8"ne9en srfaces protrsions etc( has mch more srface area than ron'e' roc8. /ncrease'srface area means increase' rates of weathering. E9entally the roc8 becomes ron'e'.

II. Mass Mo*ement The mo9ement of material propelle' by gra9ity.A. The Slope: Slope refers to a lan' srface tilte' from the hori)ontal. /t is the fn'amental nit we

are wor8ing with. The Earth is comprise' of a series of slopes with 'ifferent 'egrees ofsteepness.

!. Angle of *epose: The steepness of a slope where materials "roc8 san' gra9el cobblesetc( are at rest. 0ifferent with 'ifferent materials. Soli' roc8 wol' ha9e a steeper angleof repose. San' wol' be lower.

". 0ri9ing Dorce 9s. *esisting Dorce: This is essentially gra9ity 9erss the strength "orcohesi9eness( of the roc8s or material. A slope at the angle of repose in'icates that theresisting force balances the 'ri9ing force.

#. O9ersteepening: O9ersteepening is any process which ma8es a slope steeper. Steeperslopes are more ssceptible to the force of gra9ity becase there is less spporting

a) deep roc' underpressure

$) o*erl+ing roc' e rodedpressure released

c) pressure release9oints orm


17/29

material beneath. This is natrally case' by tectonic plift. Hhen the 'ri9ing force winsot mass mo9ement will occr.

B. lasses of -ass -o9ement "Digre ,#.,=(!. Soil reep: Slow 'ownslope mo9ement of soil an' regolith. Ai'e' by free)e$thaw

cycles. an tilt trees an' hman ma'e ob@ects imbe''e' into the gron'. Ta8eshn're's of years.

". Dlows: 5igh water content "satrate'(. /ncl'es earthflows "9iscos stays reasonably intact bt mo9es in a plastic motion( an' m'flows "higher water content an' mch fastermo9ing than an earthflow(.

#. ?an'sli'es: ?ow water content "not satrate'(. S''en mo9ement of intact bloc8s ofregolith or be'roc8. an be translational or rotational.

5. Dalls an' A9alanches: Dastest. /ncl'es roc8fall "in'i9i'al roc8s fall an' collect in aslope( an' 'ebris a9alanches "hge mass of falling roc8 'ebris an' soil(. The s''ensli'ing of be'roc8 from steep montain slopes. Often initiate' by earthKa8es. otcommon bt catastrophic.

C. Scarification "5man /n'ce' -ass -o9ement(: 5man acti9ity can reslt in increase' massmo9ement by o9ersteepening slopes. This happens with roa'bil'ing mining constrction etc.

,. *ates of -ass -o9ement:


18/29

/lu*ial rocesses and Landorms(&i*er S+stems)

(Christopherson Cha. !!)

I. Introduction *ecall that rnning water is one of the flowing sbstances which ero'e transport an''eposit earth materials to create terrestrial lan' forms. The others are ice win' an' wa9es. The forcesof rnning water "fl9ial processes( are the 'ominant processes shaping lan'forms mainly becase theyarent as geographically restricte' as the other three. The st'y of fl9ial lan'forms is terme' fl9ial

geomorphology.

II. ,rainage Basin The area "or areal nit( in which all precipitation 'rains to a specific point. Also calle'watershe'. All ri9ers ha9e a 'rainage basin which may incl'e many smaller tribtaries.

A. Open Systems: -atter "water se'iment organic material etc( an' energy enter an' exit thesystem.

B. 0rainage 0ensity: ?ength of all stream channels in basin 'i9i'e' by total area of basin.

C. 0rainage !attern: Arrangement of all stream channels in an area. See 'en'ritic trellis an'ra'ial.

,. 0ischarge: The 9olme of water mo9ing past a gi9en point in a gi9en nit if time. 7sallymeasre' in cbic feet per secon' "cfs or ftJs(.

3 R w'9 where 3 is 'ischarge w is wi'th ' is 'epth an' 9 is 9elocity

III. /lu*ial Erosion The process of water 'islo'ging se'iment. Hater mo9ing 'own steep slopes has agreat 'eal of 8inetic energy to ero'e earth materials.

A. ategories of Slope Erosion "O9erlan' Dlow(: This refers to the action of rain water an'sbseKent o9erlan' rnoff. The ero'e' materials incl'e particles of organic matter clays siltsan' an' gra9el "mostly soil materials(.

!. Splash Erosion: A rain'rop colli'ing with bare soil on a slope will 'islo'ge soil particlesan' 'eposit them a little way 'ownslope. A large rainstorm can mo9e a great 'eal of

material in this manner.

". Sheet Erosion: Hhen o9erlan' flow remo9es niform thin layers of soil from a slope.

#. *ill Erosion: Hhen o9erlan' flow begins to concentrate an' ct many small parallelchannels into a slope. These may wi'en an' 'eepen an' become gllies.

B. ategories of Stream Erosion "Streamflow(: The erosi9e powers of mo9ing water are highlyconcentrate' an' focse' in the channel. There are three forms of stream erosion.

!. 5y'ralic Action: The 'ragging force of the water an' the materials carrie' by the waterconstantly 'islo'ge materials from the stream be' an' ban8s.

". Abrasion: Abrasion is the physical crshing of be'roc8 fragments by bol'ers carrie'along by the stream. /f roc8 is highly resistant to weathering in general abrasion is theonly effecti9e process.

#. orrosion: hemical weathering "'issol9ing( of roc8 from the stream channel


19/29

I%. Stream Transportation The soli' material carrie' by a stream is the stream loa'.A. Types of ?oa'

!. 0issol9e' ?oa': 0issol9e' minerals in soltion.

". Sspen'e' ?oa': Se'iment plle' p into the water colmn. -ost of the stream loa' isin this form

#. e' ?oa': Se'iment 'ragge' along the be' "the bottom of the stream(.

B. apacity an' ompetence: apacity refers to the total amont of se'iment a stream can carryIcompetence refers to the si)e of se'iment a stream can carry. apacity an' ompetenceincrease with increase' 9elocity an' trblence. 5igh 9elocity will 'rag more >stff> along thebe' an' high trblence will case the stream to retain more sspen'e' materials.

%. Stream ,eposition The term for material 'eposite' by a stream or ri9er is all9im.A. *ole of


20/29

-ean'ering Stream "Top9iew(

*OSS SET/O

;. Dloo'plain: Area occpie' by water that exits a ri9er channel 'ring a floo'.8. Dloo'plain 'eposits: -aterials 'eposite' in floo'plain 'ring a floo'.-. atral ?e9ee: *aise' area create' precisely where ri9er exits its channel 'ring a floo'.

5appens becase this is where trblence an' 9elocity 'iminish rapi'ly.

!4. /ncrease' Se'iment ?oa': This can fill a ri9er channel ths casing it to more easily exitits ban8. ase' by natral process "glaciation( or hman processes "mining constrction etc(.

*OSS SET/O

ST&EAMC&ALLE%EES

/ L 2 2 , L A I = / L 2 2 , L A I =

&I%E&BL>// &I%E&

BL>//

/L22,LAI=,E2SITS

/L22,LAI=,E2SITS

Indicates loest lo *elocit+

Indicates highest lo *elocit+

2I=T BA&

C>T BA=?

2I=T BA&2I=T BA&

C>T BA=?C>T BA=?

2@B23 LA?E

otential uturecuto site

&ecent cuto

/ormer ri*erchannels


21/29

C. rai'e' Stream: rai'e' streams are forme' when a stream carries excess se'iment. These'iment is constantly 'eposite' along the stream be' e9entally cho8ing the stream an'casing the water to ta8e another path. The process contines.

,. *i9er 0eltas: The ability of ri9ers to transport se'iment is ltimately stoppe' at the ocean. There

is sally a massi9e area of 'eposition at the ocean. This area is calle' a 'elta.

%II./lu*ial Acti*it+ in Arid &egions 0esert lan'forms show significant e9i'ence of being inflence' byflowing water in spite of the fact that there is often little rain.

A. All9ial Dan: Srfaces in the 'esert are often ",( har' an' imper9ios "almost ba8e'( an'"&(n9egetate'. This cases the occasional rains to rn swiftly o9er the srface nslowe' by9egetation. This creates m' flows an' 'ebris flows which empty ot of the canyons an' fan otonto the 9alley floors. This forms an all9ial fan.

otice the flow of gron' water in an all9ial fan.otice that the coarser materials nearest canyon moth finer materials frthest.

B. !laya: ?ow point "9alley floor( in an ari' region. This is where water 'rains carrying only finean' 'issol9e' se'iments. E9aporation 'ominant sally salty.


22/29

Allu*ial /an and la+a

Mud /lo

,e$ris /lo

LAAA l l u * i a l / a nBedroc'


23/29

Coastal rocesses and Landorms(Christopherson Cha. !#)

I. 2ceans and TidesA. ase: Ti'es reslt from the gra9itational attraction between the Earth an' -oon an' the Sn

an' -oon.

B. Spring Ti'e "the highest ti'al range(: Occrs approximately twice a month when the -oon is in aperfect line with the Earth an' Sn. Hith both the -oon an' Sns gra9itational pll along thesame axis a large ti'al blge is create'. This cases the highest an' lowest ti'es to occr.

C. eap Ti'e "the lowest ti'al range(: Occrs approximately twice a month when the moon is at aright angle with an imaginary line @oining the Earth an' Sn. /n this case the Sn an' -oon areplling at right angles reslting in a cancellation of their forces. The 'ifference between high an'low ti'es is minimal compare' to Spring Ti'es.

,. Ti'al rrents: Occrs in bays an' estaries case' by the rise an' fall of water le9el. The ebbcurrentflows seawar' "falling ti'e( while the flood currentflows lan'war' "rising ti'e(.

!. an pro'ce high 9elocity crrents in narrow inletsI 8eeps them from being bloc8e' withse'iment.

". an carry large sspen'e' loa' of m' an' silt. E9entally forms ti'al crrent 'epositsm'flats an' salt marshes.

II. 3a*esA. ases

!. Hin': -ost wa9es are win'$'ri9en. ormally a smooth n'lation of the sea srface "inthe open ocean( the wa9elength rises an' the 9elocity slows when they reach shore "afnction of wa9elength 9s. water 'epth(. The 'istance o9er which the win' blows isterme' fetch. The longer the fetch an' the faster the win's the higher the swell "an'reslting wa9es(.

".


24/29

". Transporta) ?ongshore rrents: Ocean crrents which flow parallel to the shore. They

carry se'iment along the coast.

$) each 0rifting: each 'rifting is the mo9ement of san' along the coast whichreslts from the swash an' bac8wash of wa9es which hit the coast at an angle.

c) ?ittoral 0rift: ombination of longshore 'rift "material transporte' by a longshorecrrent( an' beach 'rift. ase' by win'Jwa9e angles stri8ing a beach.

#. 0eposition The primary 'epositional forms on a coast are beaches.

a) /n the shallow water wa9es of translation captre some se'iment from the seafloor. As they approach shoreline wa9es slow 'own often to a point where theycan 'eposit the se'iments. Ths beaches are forme'.

$) oastal erosion an' 'eposition are 9ery 'ynamic. Hhen the energy of wa9eschanges the balance between erosion an' 'eposition also shifts. ormallybeaches grow 'ring Kiet weather an' retreat "they are ero'e'( 'ring storms.

c) Some shores experience long term tren' of either accmlation an' erosion:

(i) !rogra'ation $ bil'ing ot of shore "accmlation(.(ii) *etrogra'ation $ ctting bac8 of a shore "erosion(.

5. oastal ?an'formsa) eaches: eaches are 'epositional lan'forms ma'e p of san' an' larger

se'iments $ gra9el cobblers. Smaller particles "silt clay( are sally carrie' insspension an' not 'eposite'.

$) liffsJenchesJTerraces: oastal erosion eats away coastal cliffs "by notchingn'erctting slope collapse( casing them to retreat. /f erosion is strong an'

prolonge' a broa' erosional platform is ct at the base of shore cliffs calle' awa9e$ct bench. /t is a gently sloping be'roc8 srface slightly below water le9el.The material waste' from the slope is frther ero'e' an' carrie' away bybac8wash. /t is then often 'eposite' behin' a bench to form a wa9e$bilt terrace./n time this terrace may grow so large as to co9er the wa9e$ct bench RU abeach is forme'.

c) arrier islan'sJ?agoons: arrier islan's are long narrow an' low islan'sstretching along coastlines. The main case of their formation is belie9e' to bethe brea8ing of big wa9es "'ring storms( in the shallow waters close to theshoreline. A lagoon is an isolate' "or almost isolate'( bo'y of water separate'from the sea by a barrier islan' or a san' spit across a bay. O9er time as finese'iments accmlate in a lagoon it transforms into m'flats an' then aftergrasses set in a marsh.

d) oral reefsJAtolls: oral polyps grow in warm tropical waters. /n a''ition waterhas to be shallow "abot %# m or less( since polyp reKires sn light for itsgrowth.

(i) Dringing reefs $ coral reef 'e9elope' on the n'erwater slope of the9olcano.

(ii) arrier reef $ 9olcano is slowly 'estroye' by wa9es howe9er reefcontines to grow an' bil' itself pwar'.

(iii)Atoll $ the 9olcanic islan' is completely 'estroye'.


25/29

6. Types of oastlinesa) Sbmergent oasts: oasts that experience rising water. /n these cases we

ha9e partial 'rowning of a coast. Two prominent types of sbmergence coastsare

(i) *ia coast $ 'eeply embaye' coast. ?ong an' narrow bays are in factformer lower portions of stream 9alleys now n'er water $ they are8nown as estaries.

(ii) Dior' coast $ sbmerge' glacial troghs. ?ower parts of 7$shape glacial9alleys are inn'ate' with seawater forming fior's $steep$walle' longan' 'eep inlets.

$) Emergent coasts: oasts where former sbmarine lan'forms are now expose'on lan'. Among the emergence coasts are

(i) arrier$islan' coast 1 low$lying gently sloping yong se'imentary'eposits sbseKently plifte'. /slan's form by wa9e an' win' actionfrom bars an' 'nes hel' together by beach grasses an' other9egetation.

(ii)


26/29

Glacial rocesses and Landorms(loing ice as an agent o erosion)

(Christopherson Cha. !5)

I. Introduction Glaciers ha9e in the past co9ere' 9ast areas of the worl' especially compare' to thepresent. Glacial acti9ity has been particlarly high o9er the corse of the last ,.6% million years. 0espitethe relati9e lll at present glaciers ha9e been responsible for shaping many lan'scapes we see to'ay.

A. Two -ain Types of Glaciers!. Alpine "high ele9ation(: Alpine glaciers form for the most part in montainos areas

filling narrow 9alleys with >ri9ers> of ice. Orographic precipitation is the primary factorin9ol9e' in their formation. Starts ot as a cirKe.

". ontinental "high latit'e(: ontinental Glaciers "or ice sheets( are hge expanses of icemany 8ilometers across "an' thic8( which form in col' polar regions. The only two icesheets in existence to'ay are Greenlan' an' Antarctica.

B. Dormation of Glaciers!. Annal snowfall mst excee' snowmelt: /n simple terms glaciers will form when more

snow falls than melts.

". Snowline: The term snowline is loosely applie' to mean that ele9ation in a montainosen9ironment abo9e which snow remains throgh the next years first snow. /t is onlyabo9e this line that there is the possibility for snow accmlation "an' glacial'e9elopment(

#. Transformation to /ce: Hhen layers of snow accmlate a slow process begins whichltimately reslts in the transformation of that snow to ice. This process is one of'ensification an' explsion of air. Hhen there are no longer air spaces between the icecrystals the snow has become glacial ice. The transitional term is firn.

II. Glacial Geomorpholog+ There are many similarities between alpine an' continental glaciationI we willfocs mostly on alpine as it presents a goo' mo'el. See continental below.

A. Erosion: Glaciers ha9e ama)ing erosi9e powers not rea'ily noticable. Glacial till is the collecti9eterm for any glacier relate' se'iment.

!. Types of Erosiona) Abrasion: The glacial ice collects gra9el bol'ers san' etc an' 'rags this

material along the be'roc8 srface scraping off roc8 particles. The 9ery finematerial is calle' glacial flor. This process often lea9es scars in the roc8 calle'striations.

$) !lc8ing: This is when the glacial ice free)es to chn8s of @ointe' be'roc8 an''islo'ges them. /t is 'ifficlt to 8now which one of these two processes is moreeffecti9e as they are 'ifficlt to obser9e.

&. Erosional ?an'forms

c) irKe "'epression left by a cirKe glacier(d) 5orne) Arete) 7$shape' 9alley "also calle' trogh(

(i) 5anging


27/29

B. Transport!. -ass alance: A glacial system has inpts an' otpts.

a) Accmlation Vone: The area abo9e the snowline is terme' the accmlation)one. Snowfall excee's snowmelt here.

$) Ablation Vone: The area below the snowline is terme' the ablation )one.Snowmelt excee's snowfall here.

c) EKilibrim ?ine: The bon'ary between the ablation )one an' the accmlation)one. Snowfall eKals snowmelt here. Often calle' the snowline.

d) Dlow: /ce flows from the accmlation )one to the ablation )one. arries glacialtill li8e a con9eyer belt.

-ass alance of an Alpine Glacier "si'e9iew 'iagram(

". Types of Dlow

a) !lastic Dlow: 7n'er pressre the ice at 'epth flows li8e a plastic.

$) asal Sli'ing: Sli'ing motion where ice meets be'roc8 ai'e' by the lbricationof meltwater.

2=E 2/ ACC>M>LATI2=

2=E 2/ ABLATI2=

E0uili$riumLine

Snoline


28/29

#. E9i'ence of Dlowa) re9asses: rac8s in the glacier where the glacier plls away from the montain

"bergschrn'( where it trns corners an' where it flows 'own a steep portion"icefalls(.

$) Experimental E9i'ence: Sta8es were pon'e' in a straight line across glacier"perpen'iclar to flow(. All sta8es mo9e' in relation to the stationary pointsalongsi'e the glacierI the sta8es in the mi''le flowe' fastest "friction is least inthe center of a glacier.

5. *ate of Dlow: "etween a few centimeters to ,##mJ'ay(

C. 0eposition "an' 0epositional ?an'forms(: Hhen a glacier melts it 'rops its loa'.!. -oraines: -on's of 'eposite' glacial till.

a) -e'ial: Glacial till transporte' an' 'eposite' 'own the center of a glacier.$) ?ateral: Glacial till transporte' an' 'eposite' 'own the si'e of a glacier.

c) Terminal: Glacial till transporte' an' 'eposite' at the en' of a glacier.

-oraines "Top9iew(

". Erratics "or ice rafte' bol'ers(: Single large bol'ers 'eposite' by glaciers. Often loo8ot of place an' often are of a 'ifferent roc8 type than the local be'roc8.

III. Continental Glaciation 1 Common Landorms

!. Es8er: Sna8eli8e ri'ge 'eposite' by a sb$glacial stream.

". 0rmlin: 0eposite' till streamline' in the 'irection of glacial ice mo9ement.

#. Cettle: 0epression left behin' when a bloc8 of glacial ice brea8s off an' ta8es manyyears to melt.

5. Terminal -oraine: The moraine forme' at the frthest reaches of the glacier.

6. *ecessional -oraine: ?i8e a terminal moraine forme' when the glacier stalls 'ring aretreat.

7. Otwash J Otwash !lain: -asses of materials 'eposite' by meltwater ri9ers beyon' thefrthest reaches of a glacier.

/L23

/L23

?ateral-oraine

-e'ial-oraine

Terminal-oraine


29/29

I%. leistoceneSometimes calle' the /ce Age ",.6% million $ ,#### years ago(. There ha9e been a seriesof glaciations 'ring this time. They are referre' to as glacials "when glaciers a'9ance( an' interglacials"when glaciers retreat(. See Digres ,+$&+ an' ,+$&2.

A. Extent of Glacial /ce: As recently as ,%$,2 ### years ago massi9e continental ice co9ere'mch of . America from ana'a soth well into the present 'ay 7nite' States. These icesheets score' off all regolith soils an' plants in their path.

B. Sea ?e9el Dlctations: ontinental glaciation has a profon' effect on global sea le9el.

!. ontinental Glaciers /ncrease......... Sea ?e9els 0ecrease

". ontinental Glaciers 0ecrease........ Sea ?e9els /ncrease

C. -echanisms of limate hange: There are many factors which ha9e contribte' to climatechange o9er time. Some are re9iewe' here

!. hanging Orbital *elationsa) hanging Orbital Shape ",##### yr cycle(

$) hanging 0irection of Tilt "&6### yr cycle(: alle' precession.

c) hanging 0egree of Tilt "4#### yr cycle(: Tilt crrently at &.% 'eg. 9ariesbetween &4 'eg. An' && 'eg.

". Solar

geography 101 part 3

Documents