BOOK DICTIONARY General Dictionary of Geology

7/28/2019 BOOK DICTIONARY General Dictionary of Geology

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Genera

lDictionaryof

Geology

AlvaKurniawan,JasmineA.P.,JohnM

c.Kenzie

2009byEnvironmentalGeographicStudentAssociation


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GeneralDiction

aryofGeology

3

Editedby:

AlvaKurniawan

Departmentof

EnvironmentalGeography,GadjahMadaUniversity,Yogyakarta,Indonesia

and:

JohnMc.K

enzie

Departmentof

Geology,UniversityofCalgary,C

algary,Canada

JasmineAn

itaPutri

Departmentof

Geology,UniversityofMelbourne,Melbourne,Australia

Specialthanksto:

RichardA.

Matzner

Austin,Texas,UnitedStatesofAmerica

TokuhideA

kabane

KyotoUniversity,Kyoto,Japan

NadineBar

low

UniversityofC

entralFlorida,Orlando,Florida,UnitedStatesofAmerica

Copyright2009.Env

ironmentalGeographicStudentAs

sociation(EGSA)

Bulaksumur(postalcode55282),Yogyakarta,Indonesia

Phone:(0274)920340

Fax:(0274)589595

DepartmentofEnviron

mentalGeography

GeographyFaculty

GadjahMadaUniversity

Yogyakarta,Indonesia


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GeneralDi

Tho

ction

aryof

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eoft

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GeneralDiction

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Foreword

Inth

enameofGodmostgraciousmostmerciful,becauseofH

issalvationthisdictionary

canbecompleted.Wefeltsohappybeca

usewecanfinishthisdiction

arywithoutanybigtrouble

althoughwelostoneofourbelovededitors.ThankyouverymuchforMr.TokuhideAkabana,

Mr.RichardAMatzner,andMrs.Na

dineBarlowwhichgaveusmotivationtofinishthis

dictionary.

The

subjectsofthisdictionaryaremostofgeologicaltermsbuttherearemanytermsthat

alsorelated

withgeophysics,biology,astrophysics,andgeography.Geologyisaninteresting

subjectink

nowinghistoryofEarthcreation,creatureevolution,ancientEarthlifeandEarth

conditionin

thepast;evenfindmine,coal,alsooildepositbelowEarthsurface.Petrogeologist

studygeologytofindmine,coal,oroild

eposit.Geophysicsscientiststudygeologyforrecognize

thephysicalcharacteristicsofEarthcom

ponentsuchasmagnetism,

seismicity,elasticity,Earth

thermodyna

mic,byphysicalexperimen

tsinaspecificgeological

structurewhichconsistof

specificrocksandminerals.Biologyscientiststudygeologyfortrac

ingthehistoricalevolution

ofcreatureinitsfirstappearanceuntilth

istime.Geographersalsostu

dygeologyforrecognizea

spatialphenomenonofEarthsurfacethatwereformedorinfluencedwithasequencesof

geologicale

vent.

Wehopethisdictionarycanhelp

muchingivingageneralkn

owledgeaboutmanyterms

whichbeingusedingeology.Thereis

nohumancreationthatperfectintheworldlikethis

dictionary.

Weapologizeforanymistakesthatwedidntnotice

aslongaswewritethis

dictionarya

ndwehopethateachmista

kewhichourmadedidntdisturbthefunctionofthis

dictionaryasaguidetoknowgeological

terms.Thankyouverymuch

forusingthisdictionary.

Editor

Yogyakarta,Indonesia


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GeneralDiction

aryofGeology

6

Contents

Listofedito

rs

......................................................................................................3

Dedicationpage

......................................................................................................4

Foreword

......................................................................................................5

Contents

......................................................................................................6

A

......................................................................................................8

B

......................................................................................................10

C

......................................................................................................13

D

......................................................................................................15

E

......................................................................................................18

F

......................................................................................................20

G

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H

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I

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J

......................................................................................................28

K

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L

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M

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N

......................................................................................................35

O

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P

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Q

......................................................................................................42

R

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S

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T

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U

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V

......................................................................................................54

W

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X

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Y

......................................................................................................58

Z

......................................................................................................59

References

......................................................................................................60


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8

AAa:

AtermofHawaiianorigin.Usedinreferencetoabas

altic

lavathatoccursinflowswithafissured,roughandjagged

surface.

AcidicRock:

Anigneousrock

thathasarelativelyhighsilicacontent.

Examplesaregraniteandrhyolite.Alsoseeentries

for

basic,intermedia

teandultrabasicrocks.

AcreFoot:

Thevolumeofw

aterneededtofloodoneacreofland

toa

depthofonefoot.Equivalentto43,560cubicfeet,1,233

cubicmetersor325,851gallons.Oneofthemostcommon

unitsofmeasure

usedforreservoircapacity.Alsouse

din

mineralresourcecalculations(anacrefootofcoal

isa

blockofcoalone

acreinareaandonefootthickitwe

ighs

approximately1,800tons).

Alkali:

Usedinreferencetomaterialsthatarerichinsod

ium

and/orpotassium

.

AlluvialFa

n:

A

fanshaped

wedge

of

sediment

that

typically

accumulateson

landwhereastream

emergesfrom

a

steepcanyonontoaflatarea.Inmapviewithasthesh

ape

ofanopenfan.T

ypicallyformsinaridorsemiaridclima

tes.

Alluvium:

An

unconsolidated

accumulation

ofstreamdepos

ited

sediments,includingsands,silts,claysorgravels.

AngleofRepos

e:

Themaximum

angleth

atasoil,sedimentorotherloose

materialcanbeplaced

oraccumulateandbestable.The

angleofreposevariesf

ordifferenttypesofmaterialsand

differentmoistureconditions.

AngularUnconformity:

Anerosionalsurfacethatseparatesrockunitsofdiffering

dips.The

rocks

below

the

surface

were

deposited,

deformedanderoded.Theyoungerrocksabovethen

accumulateduponthee

rosionalsurface.

Anthracite:

Thehighestrankofcoa

l.Bydefinition,acoalwithafixed

carboncontentofover91%

onadryashfreebasis.

Anthracite

coalshave

abrightluster,break

with

a

conchoidalfracture,asemimetalliclusterandaredifficult

toignite.Frequentlyre

ferredtobythelaymanas"hard

coal".

Aquiclude:

Asubsurfacerock,soilo

rsedimentunitthatdoesnotyield

usefulquantiesofwater.

Aquifer:

Asubsurfacerockorsedimentunitthatisporousand

permeable.Tobeanaq

uiferitmusthavethesetraitstoa

highenoughdegreeth

atitstoresandtransmitsuseful

quantitiesofwater.

Aquifer(artesian):

An

aquifer

that

is

bounded

above

and

below

by

impermeablerockors

edimentlayers.Thewaterinthe

aquiferisalsounder

enoughpressurethat,whenthe

aquiferistappedbya

well,thewaterrisesupthewell

boretoalevelthatisabovethetopoftheaquifer.The

watermayormaynotflowontothelandsurface.


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Aquifer(confined):

An

aquifer

tha

tis

bounded

above

and

below

by

impermeablerockorsedimentlayers.Theremayormay

notbeenough

pressureintheaquifertomakeitan

"artesianaquifer".

Aquifer(unconfined):

Anaquiferthat

isnotoverlainbyanimpermeablerock

unit.The

waterin

thisaquiferisunderatmosph

eric

pressureandisrechargedbyprecipitationthatfallson

the

landsurfacedirectlyabovetheaquifer.

Arkose:

Asandstonethatcontainsatleast25%

feldspar.Easily

recognizedbecausethefeldspargrainsaretypicallypink

andangularinsh

ape.

Arroyo:

Aflatbottomgullywithsteepsidesthatisachannelfo

ran

intermittentstream.

Asthenosp

here:

Aportionofthe

uppermantlethatisdirectlybelow

the

lithosphere.Azoneoflowstrengthintheupperma

ntle

definesthetop

oftheasthenosphere.Thisweakzone

allowstheplates

ofthelithospheretoslideacrossthe

top

oftheasthenosp

here.

Astroblem

e:

AnancientcircularscaronEarth'ssurfaceproducedby

the

impactofameteoriteorcomet.UseourGooglem

aps

pagetogetclo

seupimagesofthesemeteorimpact

structures.

Atoll:

Aringshapedgr

oupofcoralislandsthataresurroun

ded

bydeepoceanw

aterandthatencloseashallowlagoon

.


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BBackwash:

Theseawardrushofwaterdownabeachthatoccurswith

arecedingwave.

BandedIro

nOre:

Arockthatconsistsofalternatinglayersofchertand

iron

oxidemineral(u

suallyhematite)withtheironoxidein

highenoughconcentrationtobeofeconomicvalue.

BankfullStage:

Aheightofwat

erinastream

thatcompletelyfills

the

naturalchannel.

Ifthewaterrisesanyhigheraflood

will

occur.

BankStora

ge:

Waterthatseep

sintothegroundalongthebanksofa

stream

duringa

timeofhighflow.Thislossofwater

into

thegroundslightlyreducestheheightthatthestream

will

attainandthen

slowlyseepsintothestream

asthehigh

waterlevelsubsideshencetheterm"bankstorage".

Bar:

Anunderwaterridge,usuallyofsandand/orgravel,

that

formsfromthed

epositionandreworkingofsediment

sby

currentsand/or

waves.Barsoccurinrivers,rivermouths

andinoffshorew

aters.

Barchan:

Asanddunethatiscrescentshapedinmapview.Barc

han

dunesform

ina

reasoflimitedsandsupply.Theym

ove

acrossthedesertfloorwiththeirgentlyslopingconvex

sidesfacingupwindand

theirsteeplyslopingconcavesides

facingdownwind.

BarrierIsland:

Along,narrowislandthatparallelsashoreline.

Basalt:

A

darkcolored

fineg

rained

extrusive

igneous

rock

composedlargelyofplagioclasefeldsparandpyroxene.

Similarincompositiontogabbro.Basaltisthoughttobe

oneofthemaincompon

entsofoceaniccrust.

BaseFlow:

Waterthatseepsintoa

streamthroughapermeablerock

orsedimentunitthato

utcropsinthebottomorbanksof

thestream.

BaseLevel:

Thelowerlimitoferosionbyastream.Sealevelisthe

ultimate

base

level.However,lakescan

serve

asa

temporarybaselevelin

upstreamareas.

Basement:

Theigneousandmetam

orphicrocksthatexistbelowthe

oldestsedimentarycov

er.Insomeareassuchasshields

thebasementrocksmay

beexposedatthesurface.

BasicRock:

Anigneousrockthath

asarelativelylow

silicacontent.

Examplesaregabbroandbasalt.Alsoseeentriesforacidic,

intermediateandultrabasicrocks.

Basin:

Intectonics,acircular,s

ynclinelikedepressionofstrata.In

sedimentology,the

siteofaccumulation

ofa

large

thicknessofsediments.


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aryofGeology

Batholith:

Averylargeintrusiveigneousrockmassthathasb

een

exposedbyerosionandwithanexposedsurfaceare

aof

over100square

kilometers.Abatholithhasnoknown

floor.

Bathymetry:

Themeasuremen

tofoceandepthsandthepreparatio

nof

topographicmap

softheoceanfloor.

Bauxite:

Theprincipaloreofaluminum.Amixtureofaluminum

oxidesandhydroxidesthatformsfrom

intensechem

ical

weatheringofas

oilintropicalenvironments.

Bedding:

Thecharacteristicstructureofsedimentaryrocksinwhich

layersofdifferen

tcomposition,grainsizeorarrangem

ent

arestackedone

ontopofanotherinasequencewith

oldestatthebottomandyoungestatthetop.

BeddingPlane:

Adistinctsurfac

eofcontactbetweentwosedimen

tary

rocklayers.

BedLoad:

Thelarger,heavierparticlesthatarebeingtransportedby

astream.Insteadofbeingdissolvedorsuspended,these

arebeingrolled

orbouncedalong,spendingatleastpart

oftheirtimeinc

ontactwiththestreambottom.Seealso:

load,suspended

load,dissolvedload.

Bedrock:

Solidrockprese

ntbeneathanysoil,sedimentorother

surfacecover.Insomelocationsitmaybeexposedat

Earth'ssurface.

BetaParticle:

Anelectronemittedwithhighenergyandvelocityfrom

thenucleusofanatomduringradioactivedecay.

Bhorizon:

Alayerinthesoil,belo

wtheAhorizon,wherematerials

leachedfromaboveacc

umulate.Typicallyenrichedinclay

andoxides.

BiochemicalRo

cks:

Asedimentaryrockthat

formsfromthechemicalactivities

oforganisms.Organic(reefandfossiliferous)limestones

andbacterialironoresa

reexamples.

Bioturbated:

An

adjective

used

in

reference

to

a

sediment

or

sedimentary

rock.Bio

turbated

sediments

have

been

disturbedbyanimals(s

uchasburrowingwormsorshell

fish)orplantroots.The

sehavepenetratedthesediment

anddisturbedanyoralloriginalsedimentarylaminations

andstructures.Bioturbatedrocksweredisturbedinthis

way

while

stillin

the

softsedimentphase

oftheir

formation.

BituminousCoal:

Arankofcoalthatfallsbetweenanthraciteandsemi

bituminous.Themostabundantrankofcoal.Frequently

referredtobythelayma

nas"softcoal".

BlockFaultMountain:

Alinearmountainthatisboundedonbothsidesbynormal

faults.

Blowout:

Ashallow,roundortro

ughshapeddepressioninsandor

drysoilthatisformedbywinderosion.Thematerial

removed

by

the

wind

may

also

be

referred

to

as

"blowout".


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GeneralDiction

aryofGeology

Butte:

Aconspicuoushillwithsteepsidesandaflattop.The

top

isusuallyacaprockofresistantmaterial.Thisstructureis

frequentlyaner

osionalremnantinanareaofflatlying

sedimentaryrock

s.


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aryofGeology

CCaldera:

Alarge,bowlsh

apedcraterassociatedwithavolcanic

vent.Acaldera

canform

from

avolcanicblastor

the

collapse

ofa

v

olcaniccone

into

an

emptied

magma

chamber.

Carbonate

Rock:

Arockmadeupprimarilyofcarbonateminerals(mine

rals

containingtheCO

3anionicstructure).Limestone(madeup

primarilyofcalicite

CaCO3)anddolostone(made

up

primarilyofdolomiteCaMg(CO3)2arethemostcommon

examples.

CarbonicA

cid:

Aweakacid(H2C

O3)thatformsfromthereactionofwater

and

carbondioxide.Mostrain

waterisaveryw

eak

carbonicacidsolutionformedbythereactionofrainwith

smallamountsofcarbondioxideintheatmosphere.

Cataclastic

Rock:

A

brecciaofpo

wderedrockformedbycrushing

and

shearingduringtectonicmovements.

Cement:

Asolidprecipitateofcalciumcarbonate,silica,ironox

ide,

claymineralsorothermaterialsthatformswithinthep

ore

spacesofasedim

entandbindsitintoasedimentaryro

ck.

Cementation:

Theprocessesth

roughwhichchemicalprecipitatesform

withinthepores

pacesofasedimentandhelpbindit

into

asedimentaryrock.

ChemicalSedim

entaryRock:

A

rockthatformsfromthe

precipitation

ofmineral

materialfromsolution.Examplesarechertandrocksalt.

ChemicalWeat

hering:

Thebreakingdownofsurfacerockmaterialbysolutionor

chemicalalteration.Common

alteration

processesare

oxidationandhydrolysis

.

Chert:

Amicrocrystallineorc

ryptocrystallinesedimentaryrock

materialcomposed

ofSiO2.Occurs

as

nodules

and

concretionarymassesandlessfrequentlyasalayered

deposit.

Chorizon:

Thelowesthorizonof

asoilprofile.Itisbelow

theB

horizonandismadeupofweatheredbedrock.

CinderCone:

Aconeshapedhillthatconsistsofpyroclasticmaterials

ejectedfromavolcanicvent.

Cirque:

Abowlshapeddepressionwithverysteepsidesthatforms

attheheadofamounta

inglacier.Formsfromcoldclimate

weathering

processes

including

frost

wedging

and

plucking.

Clastic:

Asedimentaryrock(suc

hasshale,siltstone,sandstoneor

conglomerate)orsedim

ent(suchasmud,silt,sand,or

pebbles).An

accumulation

oftransported

weathering

debris.


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aryofGeology

Clay:

Aclasticmineralparticleofanycompositionthathasa

grainsizesmallerthan1/256mm.Thetermisalsouse

din

referencetoabroadcategoryofhydroussilicatemine

rals

inwhichthesilicatetrahedronsarearrangedintosheets.

Coal:

A

brown

orblacksedimentaryrockthatformsfrom

accumulated

plant

debris.A

combustible

rock

that

containsatleast50%(byweight)carboncompounds.

CoastalPla

in:

Anareaoflow

reliefalongacontinentalmarginthatis

underlainbythick,gentlydippingsediments.

Compactio

n:

Acompressionp

rocessthatreorientsandreshapes

the

grainsofasedim

entinresponsetotheweightofoverlying

deposits.

Composite

Cone:

Aconeshapedvolcanicmountaincomposedofalterna

ting

layersofcindersand

lava

flows.Also

known

a

sa

stratovolcano.

ConeofDe

pression:

A

coneshaped

loweringofthewatertablearoun

da

producingwell.

ContactM

etamorphism:

Alterationofaro

ck,mainlybyheat,whichoccursadjacent

toadike,sill,magmachamberorothermagmabody.

ContourLine:

Alineonamapthattra

ceslocationswherethevalueofa

variable

is

constant.

Forexample,contourlines

of

elevationtracepointso

fequalelevationacrossthemap.

Allpointsonthe"tenfoot"contourlinearetenfeetabove

sealevel.

ContourMap:

Amapthatshowsthechangeinvalueofavariableovera

geographicareathroughtheuseofcontourlines.For

example,acontourmapofelevationhaslinesthattrace

pointsofequalelevation

acrossthemap.Seealso:contour

lineandtopographicma

p.

CubicFeetPerSecond:

Aunitofmeasurefrequ

entlyusedtoquantifytherateof

flowofastream.Itiseq

ualtoavolumeofwateronefoot

highandonefootwide

movingalineardistanceofone

footinonesecond.


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GeneralDictionaryofGeology

DDatum:

A

referencelocationorelevationwhichisuseda

sa

startingpointfor

subsequentmeasurements.Sealevelisa

datum

forelevationmeasurements.Datumscanalso

be

arbitrarysuch

a

sthestartingpointforstream

stage

measurementso

rbaseduponaphysicalfeaturesuchas

thebaseofarockunit.

DaughterElement:

Theelementproducedthroughtheradioactivedecayofa

parentelement.

DebrisAva

lanche:

Thesuddendow

nslopemovementofrockandsoilo

na

steepslope.

Decollmen

t:

Ahorizontaltosu

bhorizntalfaultorshearzonewithavery

largedisplaceme

nt.Therocksabovethefaultmighth

ave

beenmovedthousandsofmetersormorerelativeto

the

rocksbelow

the

fault.Thisoftenproducesasituation

wheretherocks

abovethefaulthaveentirelydifferent

structuresthantherocksbelowthefault.

Deflation:

Theremovalofclayandsiltsizeparticlesfrom

asoilby

winderosion.Th

eterm

canalsobeusedinreferenceto

theremovalbyw

indofanyunconsolidatedmaterial.

Delta:

Adepositofsedimentthatformswhereastreamente

rsa

standingbodyof

watersuchasalakeorocean.Thename

isderivedfrom

theGr

eekletter"delta"becausethese

depositstypicallyhavea

triangularshapeinmapview.

DendriticDrain

age:

Astream

drainagepatternthatresemblestheveinsofa

leafinmapview.Occu

rsmainlywheretherocksbelow

haveauniformresistanc

etoerosion.

DensityCurrent:

Agravitydrivenflowof

densewaterdownanunderwater

slope.Theincreasedde

nsityofthewaterisaresultofa

temperaturedifference,increasedsalinityorsuspended

sedimentload.

Deposition:

Thesettlingfrom

suspensionoftransportedsediments.

Also,theprecipitationofchemicalsedimentsfrommineral

richwaters.

DesertPaveme

nt:

Agroundcoverofgranulesizeandlargerparticlesthatis

typicallyfoundinarida

reas.Thisgroundcoverofcoarse

particlesisaresidualdeposit

formedwhenthewind

selectively

removes

t

hesand,

silt

and

claysized

materials.

Detrital:

Awordusedinreferencetosedimentsorsedimentary

rocks

that

are

composed

of

particles

that

were

transportedanddeposit

edbywind,waterorice.

Diagenesis:

Allofthechangeswh

ichhappentoasedimentafter

deposition,excluding

weathering

and

metamorphism.

Diagenesisincludesco

mpaction,cementation,leaching

andreplacement.

Diatom:


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GeneralDictionaryof

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Aonecelledplan

tthatlivesintheshallowwatersoflakes,

streamsorocea

ns.Manyofthesesecreteashellor

internalpartsco

mposedofsilica.Diatomscanoccu

rin

verylargenumbe

rsandcanmakesignificantcontributions

toseafloororlakesediment.

Diatomite:

Alightcolored,

finegrainedsiliceoussedimentaryrock

thatformsfroma

sedimentrichindiatomremains.

DiatomOo

ze:

Aseafloorsedim

entthatconsistsofatleast30%diatom

remains.

Differentia

tedPlanet:

A

planetthath

aslayerscomposed

ofelements

and

mineralsofdifferentdensities.Asanexample,Earth

isa

differentiatedplanetbecauseithasametalrichcore,

surroundedbya

rockymantle,andcoveredbyacrus

tof

lowdensitymine

rals.

Dip:

Theanglethata

rockunit,faultorotherrockstructure

makeswithaho

rizontalplane.Expressedastheang

ular

differencebetweenthehorizontalplaneandthestructure.

Theangleisme

asuredinaplaneperpendicularto

the

strikeoftherock

structure.

Discharge:

Thevolumeofw

aterinaflowingstream

thatpassesa

givenlocationin

aunitoftime.Frequentlyexpressedin

cubicfeetper

second

orcubic

metersperseco

nd.

Calculatedbyth

eformulaQ

=AxVwhereQ

is

the

discharge,Aisth

ecrosssectionalareaofthechannel

and

Vistheaveragev

elocityofthestream.

Discontinu

ity:

Asurfaceseparatingrocklayersofdifferingpropertiesor

compositions.(Se

eseismicdiscontinuity.)

DissolvedLoad:

Thedissolvedmaterialb

eingcarriedbyastream.Seealso:

load,suspendedload,be

dload.

Divide:

Aridgethatseparatestw

oadjacentdrainagebasins.

Dome:

Anupliftthatisroundo

rellipticalinmapviewwithbeds

dippingawayinalldirectionsfromacentralpoint.

DrainageBasin:

Thegeographicareatha

tcontributesrunofftoastream.It

canbeoutlinedona

topographicmapbytracingthe

pointsofhighestelevation(usuallyridgecrests)between

two

adjacentstream

valleys.Also

referred

to

asa

"watershed".

DrainageDivide:

Theboundarybetweentwoadjacentdrainagebasins.

Drainagedividesareridgecrests(orlessobviouslocations

whereslopeofthelandscapechangesdirection).Runoff

producedononesideo

ftheridgeflowsintostream

"A"

andrunoffontheother

sideoftheridgeflowsintostream

"B".

Drawdown:

Aloweringofthewatertablearoundaproducingwell.The

drawdownatanygivenlocationwillbetheverticalchange

betweentheoriginalw

atertableandthelevelofthe

watertablereducedbypumping.

Drift:

Ageneralterm

forall

sedimentarymaterialsdeposited

directlyfromtheiceorm

eltwaterofaglacier.

Drumlin:


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GeneralDictionaryof

Geology

A

low,smoothlyrounded,elongatehill.Drumlins

are

depositsofcompactedtillthataresculptedbeneath

the

iceofaflowingg

lacier.Thelongaxisofadrumlinparallels

theflowdirection

oftheice.

Dune:

Amoundorridgeofwindblownsand.Typicallyfoundin

desertsandinlan

dfrom

abeach.Manydunesaremo

ved

bythewind.


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GeneralDictionaryof

Geology

EEarthflow:

Adetachedmas

sofsoilthatmovesdownslopeove

ra

curvedfailuresu

rfaceundertheinfluenceofgravity.An

earthflowismorecomplexthanaslump;ithasahig

her

moisturecontentandthemovingmassofsoilhasso

me

internalmovementor"flow".Ratesofmovement

are

typicallyafewinchesperyearbutfasterratescanoccu

r.

Earthquake:

Atremblingoftheearthcausedbyasuddenreleaseof

energystoredinsubsurfacerockunits.

EbbTide:

Atidalcurrentthatgenerallymovesseawardandoccurs

duringtheparto

fthetidecyclewhensealevelisfalling.

(seealso:floodtide)

EffluentStream:

Astreamthatgainswaterfromgroundwaterflow.Th

ese

streamsaretypic

alofhumidclimateswherewatertables

arehigh.Thedischargeofaneffluentstream

can

be

sustainedbygroundwaterflowforlongperiodsoft

ime

betweenrunoffproducingrainfallorsnowmelt.Efflu

ent

streamsgenerallyincreaseindischargedownstream

and

containwaterth

roughouttheyear.Theoppositeis

an

influentstream.

ElasticLimit:

Themaximumstressthatcanbeappliedtoabodywith

out

resultinginperm

anentdeformationtherockrevertsto

itsoriginalshape

afterthestressisremoved.Inthecaseof

afaultorafoldtheelasticlimitisexceededand

the

deformationbecomesapermanentstructureoftheroc

k.

ElasticReboundTheory:

Atheorythatexplains

theearthquakeprocess.Inthis

theory,slowlyaccumula

tingelasticstrainbuildswithina

rockmassoveranextendedlengthoftime.Thisstrainis

suddenlyreleasedthrou

ghfaultmovement,producingan

earthquake.

Electron:

A

subatomicparticle

with

a

negative

charge

and

of

negligiblemassthatorbitsthenucleusofanatom.

Elevation:

Theverticaldistancebetweenmeansealevelandapoint

orobjecton,aboveorbelowEarth'ssurface.

Eolian:

Aterm

usedinreferenc

etothewind.Eolianmaterialsor

structuresaredeposited

byorcreatedbythewind.

Eon:

Themajordivisionsofthegeologictimescale.Eonsare

dividedintointervalsk

now

as"eras".Twoeonsofthe

geologictimescalearethePhanerozoic(570millionyears

agotopresent)andtheCryptozoic(4,600millionyearsago

until570millionyearsago).

Epicenter:

ThepointontheEarth's

surfacedirectlyabovethefocusof

anearthquake.

Epoch:

Asubdivisionofgeologictimethatislongerthananage

butshorterthanaperiod.TheTertiaryPeriodisdivided

intofiveepochs.From

mostrecenttooldesttheyare:

Pliocene,Miocene,Oligo

cene,EoceneandPaleocene.

Era:


19/60

GeneralDictionaryof

Geology

Asubdivisionofgeologictimethatislongerthanaperiod

but

shorter

th

anan

eon.

Precambrian,

Paleoz

oic,

Mesozoic,andCe

nozoicaretheerasofthetimescalefrom

oldesttoyoungest.

Erosion:

A

generalterm

applied

to

the

wearing

away

and

movementofearthmaterialsbygravity,wind,waterand

ice.

Esker:

Alongwindingridgeofsortedsandsandgravel.Thou

ght

to

beformed

f

rom

sedimentdeposited

byastre

am

flowingwithinor

beneathaglacier.

EustaticSe

aLevelChange:

Ariseorfallin

sealevelthataffectstheentireea

rth.

Thoughttobecausedbyanincrease/decreasein

the

amountofavaila

blewaterorachangeinthecapacityof

oceanbasins.

Evaporatio

n:

The

processof

liquid

waterbecoming

watervapor.

Includesvaporiza

tionfrom

watersurfaces,landsurfa

ces

andsnow/icesurfaces.

Evaporite:

Achemicalsedim

entorsedimentaryrockthathasform

ed

byprecipitation

from

evaporatingwaters.Gypsum,salt,

nitratesandboratesareexamplesofevaporiteminerals.

Evapotranspiration:

Allmethodsofw

atermovingfromaliquidtowaterva

por

innature.Include

sbothevaporationandtranspiration.

Exfoliation

:

Aphysicalweatheringp

rocessinwhichconcentriclayers

ofrockareremovedfrom

anoutcrop.

ExpansiveClay

(ExpansiveSoil):

Aclaysoilthatexpandswhenwaterisaddedandcontracts

whenitdriesout.This

volumechangewhenincontact

withbuildings,roadwa

ys,orundergroundutilitiescan

causeseveredamage.

Extrusive:

Igneousrocksthatcrysta

llizeatEarth'ssurface.


20/60

GeneralDictionaryof

Geology

FFacies:

The

characterist

icsofa

rock

mass

thatreflect

its

depositionalenv

ironment.Thesecharacteristicsenable

therockmassto

bedistinguishedfromrocksdepositedin

adjacentenvironments.

Fault:

Afractureorfrac

turezoneinrockalongwhichmovem

ent

hasoccurred.

FaultBlockMountain:

Alinearmountain

thatisboundedonbothsidesbynor

mal

faults.

FaunalSuc

cession:

A

principleofr

elativedatingthatisbasedupon

the

observedsequen

ceoforganismsintherockrecord.The

relative

age

of

two

rock

units

can

frequently

be

determinedbym

atchingthefossilsfoundinthoserock

sto

theirpositionsin

therockrecord.

Felsic:

Aterm

usedtod

escribeanigneousrockthathasala

rge

percentage

oflightcolored

minerals

such

asqua

rtz,

feldspar,andmuscovite.Alsousedinreferenceto

the

magmasfromwh

ichtheserockscrystallize.Felsicrocks

are

generallyrichin

siliconandaluminum

andcontainonly

smallamounts

ofmagnesium

and

iron.Granite

and

rhyolite

are

exa

mplesoffelsicrocks.(See

mafic

to

contrast.)

Fjord:

Adeep,narrow,steepwalled,Ushapedvalleythatwas

carvedbyaglacierandisnowoccupiedbythesea.

Flood:

Anoverflowofwaterontolandsthatarenormallyabove

localwaterlevels.Can

becausedbystream

discharge

exceedingthecapacityo

fthestreamchannel,stormwinds

andreducedpressuredrawingwaterfromalakeorocean

ontothecoastline,dam

failure,lakelevelincrease,local

drainageproblemsorotherreasons.

FloodBasalt:

Asequenceofparallel

tosubparallelbasaltflowsthat

wereformedduringageologicallybriefintervaloftime

andwhichcoveredanextensivegeographicarea.Thought

tohaveformedfrom

simultaneousorsuccessivefissure

eruptions.

FloodPlain:

Anareaofalluviumcove

red,relativelylevellandalongthe

banksofastream

that

iscoveredwithwaterwhenthe

streamleavesitschanne

lduringatimeofhighflow.

FloodStage:

Awaterheightthatisreachedwhenthedischargeofa

streamexceedsthecapa

cityofthechannel.

FloodTide:

Atidalcurrentthatgenerallymoveslandwardandoccurs

duringthepartofthet

idecyclewhensealevelisrising.

(Seeneaptideforcontra

st.)

FlowingWell:

Awellthattapsanaquiferthatisunderenoughpressure

toforcewatertothesur

face.Causedwhentheaquiferhas

arechargeareaatahigh

erelevation.

FluidInclusion:


21/60

GeneralDictionaryof

Geology

Asmallamounto

ffluid(liquidand/orgas)trappedwithin

arockandwhichisthoughttorepresentthefluidfrom

whichtherockcrystallized.

Focus:

ApointbeneathEarth'ssurfacewherethevibrationsofan

earthquakearethoughttohaveoriginated.Alsoknownas

ahypocenter.

Fold:

Abendorflexure

inarockunitorseriesofrockunitsthat

hasbeencausedbycrustalmovements.

Foliation:

Theplanarorlayeredcharacteristicsofmetamorphicro

cks

thatareevidence

ofthepressuresand/ortemperaturesto

whichtherockw

asexposed.Thesecanbestructurals

uch

ascleavage,text

uralsuchasmineralgrainflattening

or

elongation,orco

mpositionalsuchasmineralsegregation

banding.

Foraminife

r:

Agroupofsinglecelledorganisms,mostlymarine,that

produceacalcium

carbonateshell.Theirshellscanm

ake

upasignificantportionofthecarbonatesedimentinso

me

areas.

Foraminife

ralOoze:

Acalcareoussea

floorsedimentcomposedofforamin

ifer

shells.

ForsetBed

s:

Thedistinctlydippingsedimentlayersdepositedon

the

frontofaprogra

dingdeltaorontheleesideofasand

dune.

Formation:

Alaterallycontinuousr

ockunitwithadistinctivesetof

characteristicsthatmakeitpossibletorecognizeandmap

fromoneoutcroporwelltoanother.Thebasicrockunitof

stratigraphy.

Fossil:

Remains,imprintsortracesofanancientorganism

that

havebeenpreservedintherockrecord.Bones,shells,

casts,tracksandexcrementcanallbecomefossils.

Fossilfuel:

Acarbonrichrockmate

rialorfluid,oforganicoriginthat

canbeproducedandburnedasafuel.Coal,oilandnatural

gasareexamplesoffossilfuels.

Fumarole:

Aventthatemitshotgases,usuallyassociatedwithpastor

currentmagmaticactivitybelow.


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GeneralDictionaryof

Geology

GGabbro:

Ablack,coarseg

rainedintrusiveigneousrockthatis

the

compositionalequivalentofbasalt.Composedofcalcium

rich

feldspars,

pyroxene

and

possibly

olivine,

but

containinglittleif

anyquartz.

GageHeight:

Ameasuredheig

htofwateraboveareferencedatum.

Frequentlyused

todescribetheheightofwaterina

stream,lake,well,canalorotherwaterbody.

GagingStation:

Afacilityonastream,lake,canal,reservoirorotherwater

bodywhereinstrumentsareinstalledtoautomatic

ally

monitorthewate

r.Measurmentssuchasstage,discharge,

watertemperatu

reandpHareautomaticallytakenand

transmitted

to

hydrologists

via

satellite,

radio

or

telephone.Measurementsfrom

thesestationsareuseful

forawidevariety

offloodprediction,watermanagement,

recreationandna

vigationpurposes.

Geochrono

logy:

Astudyofthetimerelationshipsofrockunits.Inclu

des

methodsofbothrelativeandabsolutedating.

Geomorph

ology:

The

science

of

Earth's

landforms,their

description,

classification,dist

ribution,originandsignificance.

Geosynclin

e:

AmajortroughordownwarpoftheEarth'scrust,inwhich

greatthicknessesofse

dimentaryand/orvolcanicrocks

haveaccumulated.

GeothermalGradient:

Theprogressiveincreaseoftemperaturewithdepthinto

theEarth.

Geyser:

Ahotspringthatinterm

ittentlyeruptsasprayofsteam

andhotwater.Caused

bytheheatingofgroundwater

withinaconfinedopenin

ginhotrock.

GlacialRebound:

AverygradualupliftofEarth'scrustthatoccursafterthe

weightofathickcontin

entalicesheet(whichproduced

subsidence)hasmeltedaway.

GlacialStriation

s:

Groovesandscratches

onabedrocksurfacethatwere

producedbythemovem

entofaglacier.Theorientationof

thestriationsgivesevidencetothedirectionofglacial

movement.

GlacialValley:

AvalleywithaUshapedcrosssectionthatwascutbyan

alpineglacier.

Glacier:

A

thick

mass

ofice

thatforms

on

land

from

an

accumulation

and

recr

ystallization

ofsnow

significant

enoughtopersistthroughthesummerandgrowyearby

year.Therearetwobasictypesofglaciers:1)valley(or

alpine)glaciersthatcree

pdownslopeundertheinfluence

ofgravity,and2)continentalglaciersthatflowoutward

fromathickcentralarea

undertheirownweight.

Glass:


23/60

GeneralDictionaryof

Geology

Anamorphous(

withoutcrystalstructure)igneousr

ock

thatformsfrom

veryrapidcoolingofmagma.Thera

pid

coolingdoesnotprovideenoughtimeforcrystalgrowth.

Gneiss:

A

coarsegrained

,foliated

rock

produced

by

regio

nal

metamorphism.

The

mineralgrainswithin

gneiss

are

elongated

due

to

pressure

and

the

rock

has

a

compositionalbandingduetochemicalactivity.

Graben:

Anelongated,downthrownblockboundedbytwostee

ply

dippingnormalfaults.Producedinanareaofcru

stal

extension.

GradedBedding:

Arocklayerthat

hasaprogressivechangeinparticlesize

from

toptobottom.Mostcommonisasequencew

ith

coarsegrainsatthebottom

andfiningupwards,whichis

typicallycausedb

yadecliningcurrentvelocitywithin

the

depositionalenvironment.

Granite:

A

coarsegrained,intrusive

igneous

rock

compo

sed

primarily

oflightcolored

minerals

such

as

qua

rtz,

orthoclase,sodium

plagioclase

and

muscovite

m

ica.

Graniteisthough

ttobeoneofthemaincomponentsof

continentalcrust.

Gravel:

Clasticsedimenta

ryparticlesofanycompositionthat

are

over2mmindiam

eter.

GravityAnomaly:

Ageographicareawherethegravitationalattractionis

significantlyhighe

rorsignificantlylowerthannormal.

Greenhous

eEffect:

Awarmingoftheatmo

spherecausedbycarbondioxide

andwatervaporinthelowerportionsoftheatmosphere

capturingheatthatis

radiatedfrom

andreflectedby

Earth'ssurface.

Greenstone:

Alowgrademetamorphicrockthatfrequentlycontains

greenmineralssuchaschlorite,epidoteandtalc.

GroundMorain

e:

Ablanketoftillthatisdepositedduringtheretreatofa

glacier.

GroundWater:

Waterthatexistsbelow

thewatertableinthezoneof

saturation.Ground

wa

termovesslowlyin

the

same

directionthatthewatertableslopes.

GroundWaterRechargeArea:

A

location

where

surf

ace

waterorprecipitation

can

infiltrateintotheground

andreplenishthewatersupplyof

anaquifer.

Guyot:

Aseamountwithaflatto

p.


24/60

GeneralDictionaryof

Geology

HHalfLife:

Thetimerequiredforonehalfofaradioactivesubstance

todecayintoitsd

aughtermaterial.

HangingValley:

AtributarytoaUshapedglacialvalleywhich,instead

of

enteringthevalle

yatthesamelevelasthemainstream,

entersatahigh

erelevation,frequentlyasawaterfall.

Thesedifferentstream

levelsarearesultofthera

pid

downcuttingoftheglacierbeingmuchfasterthan

the

slowerdowncuttingofthetributarystream.

HardWate

r:

Waterthathasa

significantamountofdissolvedcalcium

andmagnesium

ions.Thiswaterperformspoorlyw

ith

mostsoapsanddetergentsandleavesascalydepositin

containerswhere

itisheated

orevaporates.It

can

frequentlybeim

provedthroughtheuseofhomeba

sed

watertreatmentsystems.

Headwater(s):

The

upperportionsofa

drainage

basin

where

the

tributariesofastreamfirstbeginflow.

HeatFlow:

ThemovementofheatenergyfromthecoreoftheEa

rth

towardsthesurfa

ce.

Hogback:

Anarrowridgew

ithsteeplyinclinedsidesofnearlyeq

ual

slopes.Formedb

ydifferentialerosionofsteeplydipp

ing

rockunits.

Hornfels:

Anonfoliatedmetamorp

hicrockthatistypicallyformedby

contactmetamorphisma

roundigneousintrusions.

Horst:

An

elongatedblockof

hightopographicreliefthatis

boundedontwosidesbysteepnormalfaults.Producedin

anareaofcrustalextension.

HotSpot:

Avolcaniccenterlocated

withinalithosphericplatethatis

thoughttobecausedbyaplumeofhotmantlematerial

risingfromdepth.

HotSpring:

Anaturalspringthatdeliverswatertothesurfacethatis

ofhighertemperatureth

anthehumanbody.

Humus:

Thedarkportionofasoilthatconsistsoforganicmaterial

thatiswellenoughdecayedthattheoriginalsource

materialcannotbeidentified.

HydraulicConductivity:

Theabilityofaporou

smaterialto

transmitafluid.

Permeability.

Hydrocarbon:

Anyorganicchemicalco

mpound(gaseous,liquidorsolid)

thatiscomposedofca

rbonandhydrogen.Theterm

is

frequentlyusedinrefe

rencetofossilfuels,specifically

crudeoilandnaturalgas.

Hydrograph:


25/60

GeneralDictionaryof

Geology

Agraphthatshow

sthechangeofawaterrelatedvaria

ble

overtime.Examp

le:Astreamdischargehydrographshows

thechangeindisc

hargeofastreamovertime.

Hydrologic

Cycle:

The

naturalcycling

of

Earth's

water

between

the

atmosphere,

su

rface

and

subsurface

through

the

processes

of

evaporation,

transpiration,

percolation,

infiltration,runoffandprecipitation.

Hydrology:

ThescienceofEarth'swater,itsmovement,abundan

ce,

chemistryanddistributionon,aboveandbelow

Earth's

surface.

Hydrolysis:

Achemicalreactioninvolvingwaterthatresultsin

the

breakdownofmineralmaterial.

Hydrothermal:

Pertainingtohot

water,theactionsofhotwateror

the

productsproduce

dbytheactionsofhotwater.

HydrothermalDeposits:

Mineraldeposits

thatareformedbytheactionsof

hot

waterorgasesassociatedwithamagmaticsource.

HydrothermalMetamorphism:

Alterationofrock

byhotwatersorgasesassociatedwitha

magmaticsource.

HydrothermalVein:

Adepositofmin

eralsprecipitatedinafractureby

the

actionsofhotwa

terorgasesassociatedwithamagmatic

source.

Hypocenter:

Apointbeneathearth'ssurfacewherethevibrationsofan

earthquakearethought

tohaveoriginated.Alsoknownas

thefocus


26/60

GeneralDictionaryof

Geology

IIgneousRo

ck:

Arockformedby

thecrystallizationofmagmaorlava.

Ignimbrite:

Anigneousrockformedbythelithificationofashflow

or

pyroclasticflowdeposits.

ImpermeableLayer:

Alayerofrock,se

dimentorsoilthatdoesnotallowwa

ter

topassthrough.

Thiscouldbecausedbyalackofp

ore

space

orpore

spacesthatare

so

smallthatwa

ter

moleculeshavedifficultypassingthrough.

Infiltration

:

Themovementof

surfacewaterintoporoussoil.

InjectionW

ell:

Awellthatisusedtoforceafluidintotheground.The

injectioncouldbedonefordisposalortoplacethefluid

(suchasnaturalgas)intoasubsurfacereservoir.

InteriorDrainage:

Asystemofstrea

msthatflowintoalandlockedbasinand

evaporate.

Intermedia

teRock:

Anigneousrockthatha

sanintermediatesilicacontent.

Examplesaresyenitea

nddiorite.Alsoseeentriesfor

acidic,basicandultrabas

icrocks.

Intrusion:

Aigneousrockbodythatformedfrommagmathatforced

itswayinto,throughorb

etweensubsurfacerockunits.

Intrusive:

Igneousrocksthatcrysta

llizebelowEarth'ssurface.

Ion:

Anatomorgroupofatomsthathavegainedorlostoneor

moreelectronandasaresulthasanelectricalcharge.

IonicBond:

Achemicalbondforme

dbytheelectrostaticattraction

betweenoppositelychargedions.

IronFormation:

A

layered

deposit

of

chemical

sedimentary

rocks

containingatleast15pe

rcent(byweight)ironintheform

ofsulfide,oxide,hydroxide,orcarbonateminerals.

Isograd:

Alineonamapthat

representsaspecificdegreeof

metamorphism.Rockso

nonesideofthelinehavebeen

subjectedtoagreaterle

velofmetamorphismandonthe

othersideofthelinealo

werlevelofmetamorphism.

Isostasy:

Aconditionofgravitationalbalance(similartofloating)in

which

a

massoflightercrustalrocksare

buoyantly

supportedfrombelowbydensermantlerocks.Thecrustal

rocksabovesubsidein

tothemantleuntiltheyhave

displacedanadequate

amountofmantlematerialto

supportthem.


27/60

GeneralDictionaryof

Geology

Isotope:

Oneofseveralformsofanelement.Thesedifferentforms

havethesamenu

mberofprotonsbutvaryingnumbersof

neutrons.


28/60

GeneralDictionaryof

Geology

JJade:

Atranslucentge

mstoneconsistingofeitherjadeite

or

nephritethatis

typicallygreenincolor.Jadeisav

ery

durablestonean

disusedforavarietyofjewelryand

ornamentalobjec

ts.Typicallycutinthecabochonshape

or

carved.

Jadeite:

Ahighpressure

clinopyroxenethatisfrequentlycarved

andpolishedasa

gemstone.

Jasper:

Avarietyofcoloredchert,typicallyredorgreenandoften

foundinassociat

ionwithironores.Jasperisfrequently

usedasagemstoneorintheproductionofornaments.

Jet:

Avarietyofcoal

thatisfrequentlycutandpolished

for

jewelryorornaments.

Jetty:

Ahumanmadestructurebuiltatrightanglestoacoastline

andextendingintothewater.Jettiesarebuilttoprot

ect

anareaofshorelinefrom

theeffectsofcurrents,eros

ion

ordeposition.

Joint:

A

fracture

in

rockalong

which

there

hasbeen

no

displacement.

JointSet:

Agroupofjointsthatar

eparallelornearlyparallel.They

arefrequentlyformeda

tthesametimeintervalfrom

a

commonprocess.

JollyBalance:

Aspringbalanceused

inthedeterminationofspecific

gravity.

JuvenileWater:

Waterthatisnew

tothehydrologiccycle.Broughtto

Earth'ssurfacethroughv

olcaniceruptions.


29/60

GeneralDictiona

ryofGeology

KKarst:

A

landscapetha

tischaracterized

bythe

features

of

solutionweatheringanderosioninthesubsurface.These

featuresinclude

caves,sinkholes,disappearingstrea

ms

andsubsurfacedr

ainage.

Kerogen:

Solidorganicsub

stancesfrequentlyfoundinshales.The

organiccomponentofanoilshale.

Kettle:

Adepressionformedinglacialdepositswhenabur

ied

blockofice,leftbehindbyaretreatingglacier,melts.

KettleLake

:

Alakethatformsinakettle.

Kfeldspar:

A

potassium

feldsparsuch

asorthoclase,microcline,

sanidineoradular

ia.Alsoreferredtoaspotashfeldspar.

Kilobar:

A

unitofpressure

equalto

1000

bars

(the

mean

atmosphericpressureat100metersabovesealevelisone

bar).

Kimberlite:

Avarietyofperidotitethatisfoundinvolcanicpipeswhich

arethoughttobeintrusionsfromtheuppermantle.Many

diamonddepositsarefou

ndinkimberlitepipes.

Knickpoint:

Anabruptchangeinslo

pe.Apointonastream

profile

whereachangeingradientoccurs.Thiscouldbecaused

byachangeinunderlyingbedrockorbedrockstructure.

Knob:

Asmallhilltopthatisrou

ndinshape.


30/60

GeneralDictiona

ryofGeology

LLaccolith:

Anigneousintrusionthathasbeenforcedbetweent

wo

layeredrockunits.Thetopoftheintrusionisarch

ed

upwardsandthebottomoftheintrusionisnearlyflat.

Lahar:

Amudflowcomp

osedofwaterandvolcanicash.Lah

ars

canbetriggeredbytheflashmeltingofthesnowcapo

fa

volcanicmountainorfrom

heavyrain.Laharsarev

ery

dangerousbecausetheycanoccursuddenlyandtravelat

greatspeeds.

LaminarFlow:

Astateofuniform

flowwithinafluidinwhichthemov

ing

particles

travel

along

parallelpaths

(compare

w

ith

TurbulentFlow).

Landslide:

Adownslopemo

vementofrockandsoiloverafailure

surface

and

und

erthe

influence

ofgravity.Slum

ps,

earthflows,debris

flowsanddebrisslidesareexamples.

Lapilli:

Volcanicrockmaterialswhichareformedwhenmagmais

ejectedbyavolcano.Typicallyusedformaterialthat

rangesbetween2

and64millimetersindiameter.

LateralMoraine:

Anaccumulation

oftillalongthesidesofavalleyglacier

thatisproducedb

yiceaction.

Lava:

MoltenrockmaterialonEarth'ssurface.

LavaTube:

Atunnelbelowthesurfaceofasolidifiedlavaflow,formed

whentheexteriorportionsoftheflow

solidifyandthe

molteninternalmaterial

isdrainedaway.

Leaching:

Theremovalofsolublec

onstituentsfromarockorsoilby

movinggroundwaterorhydrothermalfluids.

LeftLateralFau

lt:

Afaultwithhorizontalm

ovement.Ifyouarestandingon

onesideofthefaultandlookacrossittheblockonthe

oppositesideofthefaulthasmovedtotheleft.(Alsosee

RightLateralFault.)

Levee:

Alongcontinuousridgebuiltbypeoplealongthebanksof

astream

tocontainthe

waterduringtimesofhighflow.

Naturalleveescanalso

bebuiltalongthebanksofa

stream.Whentheflood

waterdeceleratesuponleaving

thechannel,sedimentsq

uicklydropoutofsuspensionand

buildaridgeovertime.

Limb:

Onesideofafold.The

dippingrockunitsbetweenthe

crestofananticlineandthetroughofasyncline.

Limestone:

Asedimentaryrockconsistingofatleast50%

calcium

carbonate(CaCO2)bywe

ight.

Lineament:


31/60

GeneralDictiona

ryofGeology

Astraighttopographicfeatureofregionalextentwhichis

thoughttorepre

sentcrustalstructure.Afault,line

of

sinkholes,straightstream

stretchoralineofvolcanoes

canbeconsidered

linearfeatures.

Lithification:

Theprocessesth

roughwhichsedimentsareconverted

into

sedimentar

yrock,

including

compaction

a

nd

cementation.

Lithology:

Thestudyanddescriptionofrocks,includingtheirmine

ral

compositionand

texture.Alsousedinreferencetothe

compositionaland

texturalcharacteristicsofarock.

Lithosphere:

Therigidoutersh

elloftheearthwhichincludesthecr

ust

andaportionoftheuppermantle.

LithosphericPlate:

Alargeslabofthelithospherethatcanbemoved

by

convectioncurren

tmotionwithinthemantle.

Load:

Thetotalamount

ofsedimentbeingcarriedbyastream

or

a

glacier.

Inclu

des

suspended

materials,

dissolved

materialsandmaterialsmovedalongEarth'ssurface.(A

lso

see:bedload,dissolvedload,suspendedload.)

Lode:

Arichaccumulationofmineralsinsolidrock.Frequentlyin

the

form

ofa

vein,layeroran

area

with

a

large

concentration

ofdisseminated

particles.(See

pla

cer

depositforcontra

st.)

LongitudinalDune:

Along,narrow

sanddunethathasitslongdimension

orientedparalleltothedirectionofthewind.

LongitudinalProfile:

Acrosssectionofastream

orvalleybeginningatthe

sourceandcontinuingt

othemouth.Theseprofilesare

drawntoillustratethegradientofthestream.

LongshoreCurrent:

Aflowofwaterparallel

toacoastlinethatiscausedby

wavesstrikingthecoastatanobliqueangle.

LongshoreDrift:

Themovementofsedim

entalongacoastlinecausedby

wavesstrikingthecoast

atanobliqueangle.Thewaves

washsedimentparticles

upthebeachatanobliqueangle

andtheswashbacktotheseacarriestheparticlesdown

thegradientofthebeach.Thisproducesazigzagpathof

particlemovementalong

thebeach.

Lowland:

A

relativelyflatareainthelowerlevelsofregional

elevation.

LowVelocityZo

ne:

A

zonewithintheupp

ermantlewhereseismicwave

velocitiesarerelativelylow.Thiszoneislocatedabout35

to155milesbelowthesu

rface.

Luster:

Themannerinwhichligh

treflectsfromamineralsurface.

Metallic,submetallicand

nonmetallicarethebasictypes

ofluster.


32/60

GeneralDictiona

ryofGeology

MMafic:

Aterm

usedtodescribeanigneousrockthathasalarge

percentageofda

rkcoloredmineralssuchasamphibo

le,

pyroxene

and

olivine.Also

used

in

reference

to

the

magmasfrom

wh

ichtheserockscrystallize.Maficrocks

aregenerallyrichinironandmagnesium.Basalta

nd

gabbro

are

examplesofmafic

rocks.(See

felsic

to

contrast.)

Magma:

Moltenrockmate

rialthatoccursbelowEarth'ssurface.

MagmaChamber:

Afulloremptied

magmareservoirintheshallowportion

ofthelithosphere

.

MagmaticWater:

Waterthatisdissolvedinamagmaorwaterthat

is

releasedfromam

agma.Somemagmascancontainup

to

severalpercentdissolvedwaterbyweight.

MagneticA

nomaly:

An

increase

or

decrease

in

the

localmagneticfield

comparedtothen

ormallyexpectedvalue.

MagneticD

eclination:

ThehorizontalangulardifferencebetweenTrueNortha

nd

MagneticNorth.

MagneticInclination:

Theverticalangulardiffe

rencebetweenahorizontalplane

andtheorientationofEarth'smagneticfield.

MagneticNorth

:

Thedirectionthatacom

passpoints.Thelocationwhere

Earth'smagneticfielddip

sverticallyintotheEarth.

MagneticRever

sal:

Achangeinthepolarity

ofEarth'smagneticfieldinwhich

thenorthmagneticpolebecomesthesouthmagneticpole

andviceversa.Alsoknownasgeomagneticreversalor

polarityreversal.Earth's

magneticfieldhasreversedmany

timesinthepastandthetimeintervalsbetweenthese

changesareknownaspo

larityepochs.

MagneticStratigraphy:

ThecorrelationofrockunitsandstudyofEarth'shistory

usingmagneticeventsandmagneticepochsasatime

reference.

Magnetometer:

Aninstrumentdesigned

tomeasurethestrengthand

characterofEarth'smagn

eticfield.

Magnitude:

Ameasureofearthquake

strengthbasedupontheamount

ofground

motion

experienced

and

corrected

forthe

distancebetweentheobservationpointandtheepicenter.

Thereareseveralmagnitudescalesinuse.

Manganesenod

ule:

Aroundedconcretion,richinmanganesemineralswith

minorconcentrationsof

cobalt,copperandnickel.These

occurinabundanceonsomepartsofthedeepoceanfloor

and

have

been

considered

asa

potentialsource

of

manganese.

Mantle:


33/60

GeneralDictiona

ryofGeology

AmajorsubdivisionofEarth'sinternalstructure.Located

betweenthebase

ofthecrustandoverlyingthecore.

MantlePlume:

Arisingmassofhotmantlematerialthatcancreate

an

areaofvolcanic

activityinthecenterofalithosphe

ric

plate.

Massive:

A

term

used

in

reference

to

a

rock

unitthat

is

homogeneousint

exture,fabricandappearance.

MassWasting(alsoMassMovemen

t):

Ageneraltermusedforanydownslopemovementofro

ck,

soil,snoworiceundertheinfluenceofgravity.Includ

es:

landslides,creep,rockfallsandavalanches.

Meanderin

gStream:

Astream

thatha

smanybends(meanders).Thistype

of

drainage

pattern

usually

developson

a

nearly

le

vel

landscapeandwherethebanksofthestream

areeasily

eroded.

MechanicalWeathering:

A

generalterm

applied

to

a

variety

ofweather

ing

processesthatresultintheparticlesizereductionofrock

materialswithno

changeincomposition.Frostaction,salt

crystalgrowthandpressurerelieffracturingareexamples.

Alsoknownasphysicalweathering.

MedialMoraine:

Astreakoftillin

thecenterofaglacier.Thesearefou

nd

downslopefrom

thejunctionoftwoglaciersandarea

mergingoftheirla

teralmorainedeposits.

MedicalGe

ology:

Thestudyofhumanhea

lthrelatedtogeology.Examples

wouldincludethecorre

lationofdiseaseorvitalitywith

residencesoverspecific

typesofbedrock

orhealth

problemsassociatedwithexposuretospecificmineral

materials.

Metamorphism:

Alterationoftheminerals,texturesandcompositionofa

rockcausedbyexposuretoheat,pressureandchemical

actions.

MeteoricWater:

Waterfrom

theatmosphere,suchasrain,snow,hail,or

sleet.

Meteor:

A

meteoroid

that

penetrates

Earth's

atmosphere,

producingastreakofbrig

htlightcausedbyincineration.

Meteorite:

Aparticleofironorrock

thathasfallentoEarth'ssurface

frominterplanetaryspac

e.

Meteoroid:

Aparticleofironorrockfoundininterplanetaryspace.

Distinguished

from

planetsorasteroidsbyitsmuch

smallersize.

Microseism:

AvibrationoftheEarth

thatisunrelatedtoearthquake

activityinsteaditiscau

sedbywind,movingtrees,ocean

wavesorhumanactivity.

Mineral:

A

naturallyoccurring,

inorganicsolid

with

a

definite

chemicalcompositionandanorderedinternalstructure.


34/60

GeneralDictiona

ryofGeology

Mineralogy

:

The

studyofminerals

theircomposition,structu

re,

formation,uses,

properties,occurrenceandgeograp

hic

distribution.

MohorovicicDiscontinuity:

The

boundary

b

etween

the

crust

and

the

mantle.

Frequentlyreferre

dtoastheMoho.

MohsHard

nessScale:

Acollectionofm

ineralsrangingfrom

verysofttovery

hard.

Use

as

a

comparison

scale

during

mine

ral

identification.Fro

msoftesttohardest,thetenminerals

are:talc1,gypsum2,calcite3,fluorite4,apatite

5,

orthoclase6,quartz7,topaz8,corundum9,anddiamo

nd

10.Developedby

FriedrichMohs,aGermanmineralogist

intheearly1800's

.

Monocline:

Anareaofincreas

eddipinotherwisegentlydippingstra

ta.

Moraine:

Amound,ridgeorgroundcoveringofunstratifieda

nd

unsortedtill,depo

sitedbyiceactionorbymeltingaway

of

aglacier.

Mountain:

Ageneralterm

usedinreferencetoanareathatisa

ta

conspicuouslyhig

herelevationthansurroundinglan

ds.

Mountainsarelar

gerthanhillsandaresignificantenou

gh

inreliefthattheyaregivennamesbylocalresidents.

Mudflow:

Atypeofmassm

ovementcomposedmainlyofclays

ize

materialswithahighenoughwatercontentthatitflo

ws

readily.

Mudstone:

Asedimentaryrockcom

posedofclaysizeparticlesbut

lackingthestratifiedstructurethatischaracteristicofa

shale.

M.Y.:

Millionyearsabbreviation.

M.Y.A.:

Millionyearsagoabbreviation.

Mylonite:

Abrecciatedmetamorph

icrockfrequentlyfoundinafault

zone.Thefracturedtex

tureisthoughttoform

bythe

crushingactionsoffaultm

ovement.


35/60

GeneralDictiona

ryofGeology

NNannofossils:

Agenerictermus

edinreferencetoverysmallfossilsthat

areatthelimitofresolutionbyalightmicroscope.Th

ey

arethereforestudiedwithelectronmicroscopesandare

frequentlyfossildiscoastersandcoccoliths.

Nappe:

Alargeslabofea

rth'ssurfacethathasbeenmovedina

horizontalornea

rhorizontaldirectionoveraplane

of

separation.Thismotioncanbeproducedbyfaulting

or

sliding.Theterm

isgenerallyusedforverylargeslabs

whicharemanysq

uarekilometersormilesinsurfacearea.

NativeMet

al:

Anaturaldepositofametallicelementsuchasgold,silv

er,

copperorironina

pureform.

NaturalBridge:

Anarchshapedrockformationproducedbyweathering

and/orerosion.

NaturalGas:

Naturallyoccurrin

ghydrocarbonsthatexistinsubsurface

rockunitsinthe

gaseousstate.Methaneisthemost

abundantbutethane,propaneandothersalsooccur.

NaturalLev

ee:

Amoundofsedimentthatparallelsastream

channel

formingaleveelikedeposit.Whenfloodwatersleavethe

normalstreamchannelandenterthefloodplainthereisa

reductionofvelocitythatcausessuspendedsediments

to

falltothebottom,producingthisdeposit.

Neaptide:

Adailytidalrangeofmin

imalamplitudethatoccurswhen

themoonandsunarepositionedat90degreestoone

another.

In

this

moo

nearthsun

configuration,

the

gravitationalattractiono

fthemoonandsuncompetefor

Earth'swater.Occursatthefirstandthirdquartersofthe

moon.Seespringtidefor

contrast.

Nebula:

AcloudofinterstellardustthatisfaintlyvisiblefromEarth.

Neutron:

Asubatomicparticle,con

tainedinthenucleusofanatom.

Ithasnoelectricalcharg

eandamasssimilartothatofa

proton.

Nodule:

Amineralmassthathasadifferentcompositionorismore

weatheringresistantthanitssurroundingrock.Theseare

normally

rounded

in

s

hape.Examplesinclude:chert

massesinalimestonerockunit,pyritemassesinacoal

seam,orcarbonatemass

esinashale.Inmostcasesthese

"nodules"haveformedwithintherockunitoritsformer

sedimentmass.Thete

rmisalso

applied

to

rounded

massesofmanganesem

ineralsthatoccuronsomeparts

oftheoceanfloor.

NonPointSourcePollution:

Pollutionthatdoesnoto

riginateatasinglelocation.Inan

urbanarearunoffwater

canbepollutedasitflowstoa

stream

by

gasoline,a

ntifreeze,road

salt

or

other

contaminants.Inruralareasrunoffcanbecontaminated

byinsecticides,manure,

orfertilizer.Thiscontamination

canbesignificantbutcannotbetracedbacktoaspecific

source.

NormalFault:


36/60

GeneralDictiona

ryofGeology

Afaultwithverticalmovementandaninclinedfaultplane.

Theblockabovethefaulthasmoveddownrelativetothe

blockbelowthefa

ult.


37/60

GeneralDictiona

ryofGeology

OObliqueSlipFault:

Afaultthathasb

othhorizontalandverticalelements

of

displacement.

Obsidian:

Aglassyigneousrockwithacompositionsimilartogranite.

Theglassytexture

isaresultofcoolingsofastthatmine

ral

latticeswerenotd

eveloped.

OilField:

Thegeographicar

eaaboveanundergroundaccumulation

ofoilandnaturalgas.

OilShale:

Adarkcoloredshalecontaininganunusualamount

of

solidorganicmaterial.Thisshalecanbecrusheda

nd

heatedtoliberategaseousandliquidhydrocarbons.

At

presenttheexpen

diturerequiredtoprocessoilshaleinto

a

fuel

makes

this

effort

marginally

profitable

or

unprofitable.

OldAge:

Astageinthedevelopmentofalandscapewhenstreams

havealowgradie

ntandmeanderbackandforthacross

broadfloodplains.Thelandscapeismarkedbymeander

scarsandoxbowlakes.

Oolite:

Asmallsphereof

calcium

carbonatenomorethanafew

millimetersindiameterandwithaconcentricinternal

structure.These

spheresarethoughttohaveformed

by

inorganicprecipitationofcalcium

carbonateinverythin

layersaroundagrainofs

andoraparticleofshellorcoral.

Arockcomposedprimarilyofoolites.

Oolitic:

A

limestonetexturethatischaracterizedbyspherical

grainsofcalcium

carbo

natewithaconcentricinternal

structure.Thesegrainsa

rethoughttoform

byinorganic

precipitationofcalciumcarbonatearoundasandgrainor

shellparticlenucleus.

Opaque:

Anadjectiveusedinreferencetoasubstancethatdoes

notallow

lightofvisiblewavelengthtoenterorpass

through.Mineralswitha

metallicorsubmetalliclusterare

normallyopaque.

OphioliteSuite:

Thetypicalsequenceof

rocksintheoceaniccrust:from

bottom

totop:ultrabas

icrocks,gabbro,sheeteddikes,

pillowbasalts,andseafloorsediments.Igneousrocksand

deepseasedimentsassociatedwithdivergencezonesand

theseafloorenvironmen

t.

Orbit:

Anellipticalorhyperbo

licpathtraveledbyasatellite

objectaroundamoremassivebody.Forexample,the

EarthorbitstheSun.

OreDeposit:

Anaturalaccumulation

ofametal,gemstoneorother

valuable

mineralsubstance,which

isrich

enough

in

concentrationthatitcanbeminedandprocessedata

profit.

OreMineral:

Amineralthatcontainsahighenoughconcentrationofa

usefulelement

or

compound

that

the

element

or

compoundcanbeextract

edataprofit.


38/60

GeneralDictiona

ryofGeology

OriginalHo

rizontality:

Oneoftheprinciplesofrelativedating.Baseduponthe

goodassumption

thatsedimentaryrocksaredeposited

in

horizontalornear

lyhorizontallayers;thenifsedimentary

layersarefoundinaninclinedorientationtheforcethat

movedthemtothatorientationmusthavebeenapplied

at

sometimeafterth

eirdeposition.

OrogenicBelt:

Alinearorarcuate

regionoffoldedandupliftedrocks.

Orogeny:

Acompressivete

ctonicprocessthatresultsininten

se

folding,reversefaulting,crustalthickening,upliftandde

ep

plutonicactivity.A

mountainbuildingepisode.

OscillationRippleMarks:

Symmetricalridge

sinsandorothersedimentthatare

causedbyabackandforthwaveaction.

Outcrop:

Anexposureofbe

drock.Outcropscanbeformednatura

lly

or

by

human

a

ction.Stream

erosion

and

highw

ay

constructioncanp

roduceoutcrops.

Outfall:

Alocationwhere

waterisdischarged.Normallyused

in

referencetowhe

reawatertreatmentfacilityreleases

treatedwaterinto

theenvironment.

Outgassing:

Thereleaseofju

venilegasesandwatertothesurfa

ce

fromamagmasou

rce.

Outwash:

Sortedandstratifiedse

dimentdepositedinfrontofa

glacierbymeltwaterstreams.

OverturnedFold

:

Afoldthathasbothlimbsdippinginthesamedirection,

resultingfromoneofthoselimbsbeingrotatedthroughan

angleofatleast90degre

es.Overturnedfoldsarefoundin

areasofintensedeform

ation.Thenameoverturnedis

givenbecausethestrat

aononelimbofthefoldare

"overturned"orupsidedown.

OxbowLake:

Acrescentshapedlake

thatformswhenameandering

streamchangescourse.S

uchchangesincoursefrequently

occurduringfloodeventswhenoverbankwaterserodea

newchannel.

Oxidation:

Achemicalreactioninwhichsubstancescombinewith

oxygen.Forexample,the

combinationofironwithoxygen

toformanironoxide.


39/60

GeneralDictiona

ryofGeology

PPahoehoe:

AHawaiianterm

foralavaflowthathasasurfaceflow

structureappeara

ncethatlookslikecoiledropeorco

rd.

Seeaaforcontrast.

Paleoclimate:

Theclimateofag

ivenareaataspecifictimeinthepa

st.

Paleoclimatescan

bereadfrom

therocksmuchasare

as

withdifferenttyp

esofclimatesproducesedimentsw

ith

specificcharacteristicstoday.

PaleocurrentMap:

Amapthatshows

thedirectionsofcurrentsatthetime

of

sedimentdeposition.Thesedirectionscanbedetermin

ed

throughthestudyofcrossbedding,ripplemarks,tool

marksandothersedimentarystructures.

Paleogeogr

aphicMap:

A

map

thatshows

the

distribution

ofsedimentary

environmentsataspecifictimeinthepast.Thesema

ps

aremadebystud

yingtherockrecordtocorrelatero

ck

unitsthatweredepositedatthesametime,thenrelating

rockcharacteristic

stospecificsedimentaryenvironments.

Paleomagnetism:

ThestudyofEarth

'smagneticfieldovertime.Whenrocks

that

contain

magnetic

minerals

are

deposited,the

character(verticalandhorizontalorientation)ofEarth's

magneticfieldislockedwithintherocks.Thisinformation

canbeusedtostudychangesinEarth'smagneticfield

as

wellasthemovem

entofplatesovertime.

Paleontology:

Thestudyofancientlifethroughfossils.

Pangaea:

Alargecontinentallandm

assthatexistedfromabout300

millionyearsagothroughabout200millionyearsago.It

includedmostoftheco

ntinentallithospherepresentat

thattime.Ithassincebr

okenupandthefragmentshave

driftedtobecometheconfigurationofEarth'spresentday

continents.

Panthalassa:

Theancientoceanthatsu

rroundedthePangaealandmass.

ParentElement:

Aradioactiveelementthatspontaneouslydecaysintoa

newsubstance.Theproductofthisdecayisknownasa

"daughter"element.

PeakFlow:

Themaximum

instantaneousdischargeofastream

ata

specificlocation.Correspondstothehigheststageofa

flood.

Peat:

Anaccumulationofunc

onsolidatedplantdebristhatif

buried

and

preserved

could

become

coal.

Special

conditionsarerequiredt

oaccumulateandpreserveplant

materials.Theseconditionsaremostoftenfoundina

marshorswampwhere

watercoverpreventsoxidation

andattackbymostorgan

isms.

Pediment:

Abroad,gentlyslopingerosionalsurfaceoflowlocalrelief

adjacenttoanerodingclifformountainrange.Theareais

likelycoveredwithsediments.

Pegmatite:


40/60

GeneralDictiona

ryofGeology

Averycoarsegra

inedigneousrock,normallyofgranitic

composition.Typicallyformsduringthefinalstates

of

magma

chamber

crystallization

when

the

high

water

contentsolutionsallowrapidcrystalgrowth.

PelagicSed

iment:

Aoceansediment

thataccumulatesfarenoughfromla

nd

thatdetritalmaterialsareaminorcomponent.The

se

sedimentsarelarg

elycomposedofthetinyshelldebris

of

radiolariansandfo

raminifera.

PerchedWaterTable:

Awatertabletha

tisisolatedfrom

andhigherthant

he

regionalwaterta

ble.Thiscanoccurwhenahilltop

is

underlainbyanim

permeablerockunit.Infiltratingwaters

stackupontheimpermeableunit,creatinganisolat

ed

watertablethat

ishigherthanthewatertableoft

he

surroundingland.

Peridotite:

Adarkcolored,co

arsegrainedigneousrockthatisma

de

upmainlyofolivineandpyroxene,withverylittlequa

rtz

orfeldspar.

Permeability:

Ameasureofhow

wellamaterialcantransmitwat

er.

Materialssuchasgravel,thattransmitwaterquickly,ha

ve

highvaluesofpermeability.Materialssuchasshale,that

transmitwaterpoorly,havelow

values.Permeability

is

primarilydeterminedbythesizeoftheporespacesa

nd

theirdegreeofinterconnection.Permeabilitymeasures

areexpressedinu

nitsofvelocity,suchascentimetersp

er

second,andassum

eagradientofoneverticalfootofdr

op

perlinearfoot.

pH:

Arelativemeasur

eoftheacidityoralkalinityofawater

baseduponascalethatrangesbetween0and14with

7

beingneutral.ValuesofpHbelow7indicateacidsolutio

ns

andvaluesofpHa

bove7indicatebasicsolutions.

PhysicalWeathering:

A

generalterm

applied

to

a

variety

ofweathering

processesthatresultintheparticlesizereductionofrock

materialswithnochange

incomposition.Frostaction,salt

crystalgrowthandpressu

rerelieffracturingareexamples.

Alsoknownasmechanica

lweathering.

PlacerDeposit:

Amassofstreamsedime

ntthatcontainsaneconomically

significant

concentration

of

mineral

particles.

This

accumulationofmineralparticlesisaresultoftheirbeing

ofhighspecificgravity

orresistanttoabrasion.Gold,

magnetite,anddiamonds

canbefoundinplacerdeposits.

PlateauBasalt:

Asequenceofparallel

tosubparallelbasaltflowsthat

wereformedduringageologicallybriefintervaloftime

andwhichcoveredanextensivegeographicarea.Thought

tohaveformedfrom

simultaneousorsuccessivefissure

eruptions.

PointSourcePo

llution:

Watercontaminationtha

tcanbetracedtoasinglepoint.

Atoxicmaterialspillan

dasewagedischargepipeare

examplesofpointsources.

PolarityEpoch:

AnintervaloftimebetweenreversalsofEarth'smagnetic

field.

PolarityEvent:

Aspecificeventintheh

istoryofEarth'smagneticfield.

Usuallyusedinreference

toaspecificpolarityreversal.

PolarityReversa

l:

AchangeinthepolarityofEarth'smagneticfieldinwhich

thenorthmagneticpolebecomesthesouthmagneticpole

andviceversa.Alsoknownasgeomagneticreversalor


41/60


magneticreversal.Earth'smagneticfieldhasrevers

ed

manytimesinthepastandthetimeintervalsbetwe

en

thesechangesare

knownaspolarityepochs.

Porosity:

Thevolumeofporespaceinarock,sedimentorsoil.

Usuallyexpressed

asapercentage.Thisporespacec

an

includeopenings

betweengrains,fractureopeningsa

nd

caverns.

PotableWa

ter:

Waterthatisofad

equatequalityfordrinking.

Pothole:

Acylindricalorh

emisphericalholdinthebedrockofa

stream

thatisformedfrom

thecontinualswirlingmotion

ofsandandgravelbyswirlingcurrents.

PPM:

Anabbreviationfo

rpartspermillion.

Precipitatio

n:

Movementofwaterfromtheatmospheretothelandor

to

asurfacewaterbody.Rain,hail,snow,dew,andsleetare

allexamplesofpre

cipitation.

PrimarySeismicWaves:

Thefastestsetofearthquakevibrationsalsoknownas

P

waves.Theymove

throughtheEarthincompressiona

nd

expansionmotions(muchlikesoundwavesmovethrou

gh

air).Calledprimarybecausetheyarethefirstrecordeda

ta

seismograph.Prim

arywavesareabletotravelthrou

gh

bothsolidsandliquids.

ProtoSun:

Anintermediatestageinthedevelopmentofastarin

whichalargecloudofdu

standgasesgraduallycondenses

throughgravitationalactions.

ProvenReserves:

Mineraldepositsthath

avebeen

explored

thoroughly

enoughtobequantifiedb

utwhicharestillintheground.

Pumice:

Avesicularvolcanicglass

ofgraniticcomposition.Ithasso

manyvesiclesthatithasaverylow

specificgravity

sometimeslowenoughto

floatonwater.

Pwave:

Primaryseismicwaves.

Thefastestsetofearthquake

vibrations.Theymoveth

roughtheEarthincompression

andexpansionmotions

(muchlikesoundwavesmove

throughair).Calledprim

arybecausetheyarethefirst

recordedataseismograph.Primarywavesareableto

travelthroughbothsolids

andliquids.

PyroclasticRock

:

Arockformedwhensmallparticlesofmagmaareblown

fromtheventofavolcanobyescapinggas.

PyroxeneGranu

lite:

Acoarsegrainedcontact

metamorphicrockthatisformed

athightemperaturesand

lowpressuresandwhichisrich

inpyroxeneminerals


42/60


QQuarry:

Asurfacemineus

uallyfortheextractionofconstruction

stone.

Quartz:

Oneofthemostabundantmineralsintheearth'scru

st.

HasachemicalcompositionofSiO2andahardness

of

seven.Oneofthe

indexmineralsinMoh'sHardnessSca

le.

Occursinsedimentary,metamorphicandigneousrocks.

QuartzArenite:

Asandstoneconsistingofatleast95%quartz.

Quartzite:

Ametamorphicrockformedbythealterationofsandsto

ne

byheat,pressureandchemicalactivity.

Quartzose:

Anadjectiveused

inreferencetoarockthatiscompost

ed

primarilyofquartz

.

Quicksand:

Abedofsandthathasahighwatercontent.Thewater

within

thesand

isoften

flowingthrough

the

spac

es

betweenthesandgrains.Thiscreatesasoft,fluidlike

materialthatyield

seasilytopressureandinwhichhea

vy

objectswillsink.

Quicksilver:

Anicknamefortheeleme

ntmercury.


43/60


RRadialDrainage:

Adrainagepatter

ninwhichstream

channelsrunaw

ay

fromacentralhigh

pointsuchasavolcanoordome.

Radiolarian

:

Agroupofonec

elledmarineanimalswithasiliceo

us

skeleton

thatoccupiesshallow

portionsofthewater

column.Radiolarianshavearangefrom

Cambrian

to

present.

Radiolarian

Ooze:

Adeepseapelagicsedimentthatcontainsatleast30%

siliceousradiolaria

nremains.

RatingCurv

e:

Aplotthatshows

therelationshipbetweenthestagea

nd

discharge(streamflow)ofaspecificstream

ataspecific

location.Itiscusto

marytoplotstreamstageontheya

xis

oftheplotanddischargeonthexaxis.Theresulting

relationshipisnormallyacurve.Ratingcurvescanbeus

ed

to

estimate

discharge

(which

istime

consuming

a

nd

expensivetomeasure)usingasinglestagemeasureme

nt

(whichcanbecollectedwithautomaticequipment).T

he

principleofaratin

gcurveenableshydrologiststomonitor

thedischargeofm

anystreamssimultaneouslyoncegag

es

havebeenplaced

tocollectandreportthestageoft

he

stream.

ReactionSe

ries:

A

seriesofinter

actionsbetween

ameltand

mine

ral

crystalsincontact

withthemelt.Inareactionseriest

he

firstformedcrysta

ls(highesttemperatureminerals)react

withthemelttoproduceanewmineral.

Recharge:

Wateraddedtoanaquife

rorotherwaterbody.Anaquifer

isrechargedbyprecipitationinanareawheretheaquifer

hasaporousconnectiont

othesurface.

RechargeArea:

Thegeographicareawhere

waterinfiltratesinto

the

groundandentersanaqu

ifer.

Recrystallization

:

A

solidstatereactioninwhichtheatomsofexisting

crystalswithinarockare

reorganizedinresponsetoheat

and/orpressure.Therecrystallized

mineralgrainsare

typicallylargerinsizethantheoriginalcrystals.

RectangularDra

inage:

A

drainagepatterninwhichstream

channelsdevelop

withinalargescalenetworkofintersectingjoints.This

drainagepatternischara

cterizedbyrightanglebendsin

thechannelsofstreamsa

ndstreamsthatintersectatright

angles.

RecumbentFold

:

Anoverturnedfoldthat

hastwolimbswhicharenearly

horizontal.

Refraction:

Thebendingofaseismic

waveasitentersamaterialof

differentdensity,or,the

bendingofabeam

oflightasit

entersamaterialofdiffer

entrefractiveindex.

RegionalMetam

orphism:

Metamorphism

across

a

broad

area

caused

by

the

elevatedtemperaturesandpressuresofplatecollisionor

deepburial.

Regolith:


44/

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BOOK DICTIONARY General Dictionary of Geology

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