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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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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
Ge
sdicti
eoft
logynary
isdict
Sy
edic
at
onar
y
ney
at
dtoJ
contr
Decem
smine
butor
ber20
Anita
hich8
Putri
eadin
4
s
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aryofGeology
5
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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aryofGeology
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Contents
Listofedito
rs
......................................................................................................3
Dedicationpage
......................................................................................................4
Foreword
......................................................................................................5
Contents
......................................................................................................6
A
......................................................................................................8
B
......................................................................................................10
C
......................................................................................................13
D
......................................................................................................15
E
......................................................................................................18
F
......................................................................................................20
G
......................................................................................................22
H
......................................................................................................24
I
......................................................................................................26
J
......................................................................................................28
K
......................................................................................................29
L
......................................................................................................30
M
......................................................................................................32
N
......................................................................................................35
O
......................................................................................................37
P
......................................................................................................39
Q
......................................................................................................42
R
......................................................................................................43
S
......................................................................................................46
T
......................................................................................................50
U
......................................................................................................53
V
......................................................................................................54
W
......................................................................................................56
X
......................................................................................................57
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Y
......................................................................................................58
Z
......................................................................................................59
References
......................................................................................................60
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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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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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Butte:
Aconspicuoushillwithsteepsidesandaflattop.The
top
isusuallyacaprockofresistantmaterial.Thisstructureis
frequentlyaner
osionalremnantinanareaofflatlying
sedimentaryrock
s.
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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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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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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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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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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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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:
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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.
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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:
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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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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:
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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.
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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:
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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
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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.
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Isotope:
Oneofseveralformsofanelement.Thesedifferentforms
havethesamenu
mberofprotonsbutvaryingnumbersof
neutrons.
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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.
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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.
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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:
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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.
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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:
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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.
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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.
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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:
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Afaultwithverticalmovementandaninclinedfaultplane.
Theblockabovethefaulthasmoveddownrelativetothe
blockbelowthefa
ult.
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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.
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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.
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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:
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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
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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
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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.
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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:
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