PZGLI007-品質(zhì)管理-石油資源勘查專業(yè)英語(yǔ)

Unit1BasicGeology

Lesson1Geology

Earthscience(alsoknownasgeoscience,thegeosciencesortheEarthsciences),isan

all-embracingtermforthesciencesrelatedtotheplanetEarth.Itisarguablyaspecialcasein

planetaryscience,theEarthbeingtheonlyknownlife-bearingplanet.Therearebothreductionist

andholisticapproachestoEarthsciences.TheformaldisciplineofEarthSciencesmayincludethe

studyoftheatmosphere,oceansandbiosphere,aswellasthesolidearth.Geologyisgenerally

categorizedwithinthegeosciences.

Geology(fromtheGreek,geo,"earth"and,logos,“speech")isanaturalscience,which

studiesthegeologyscienceoftheearth'shistory,composition,andstructure,andtheassociated

processes.Itdrawsuponchemistry,biology,physics,astronomy,andmathematics(notably

statistics)forsupportofitsformulations.

Geologyisaverycomplexscience.TherearemanybranchesofGeology,whichcanbe

groupedunderthemajorheadingsofphysicalandhistoricalgeology.

PhysicalGeology

Physicalgeologyincludesmineralogy,thestudyofthechemicalcompositionandstructureof

minerals;petrology,thestudyofthecompositionandoriginofrock;geomorphology,thestudyof

theoriginoflandformsandtheirsmodificationbydynamicprocesses;geochemistry,thestudyof

thechemicalcompositionoftheearthmaterialsandthechemicalchangesthatoccurwithinthe

earthandonitssurface;geophysics,thestudyofthebehaviorofrockmaterialsandinresponseto

stressesandaccordingtotheprinciplesofphysics;sedimentology,thescienceoftheerosionand

depositionofrockparticlesbywind,water,orice;structuralgeology,thestudyoftheforcesthat

deformtheearth'srocksandthedescriptionandmappingofdeformedrockbodies;economic

geology,thestudyoftheexplorationandrecoveryofnaturalresources,suchasoresand

petroleum;andengineeringgeology,thestudyoftheinteractionoftheearth'scrustwith

human-madestructuressuchastunnel,mines,dams,bridges,andbuildingfoundations.

Historicalgeology

Historicalgeologydealswiththehistoricaldevelopmentoftheearthfromthestudyofits

rocks.Theyareanalyzedtodeterminetheirstructure,composition,andinterrelationshipsandare

examinedforremainsofpastlife.Historicalgeologyincludespaleontology,thesystematicstudy

ofpastlifeforms;stratigraphy,oflayeredrocksandtheirinterrelationships;paleogeography,of

thelocationsofancientlandmassesandtheirboundaries;andgeologicmapping,the

superimposingofgeologicinformationuponexistingtopographicmaps.

Historicalgeologistsdividealltimesincetheinformationoftheearliestknownrocks(c,4

billionyearsago)intofourmajordivisions:thePrecambrian,Paleozoic,Mesozoic,andCenozoic

eras.Each,excepttheCenozoic,endedwithprofoundchangesinthedispositionoftheearth's

continentsandmountainsandwascharacterizedbytheemergenceofnewformsoflife.Broad

cyclicalpatterns,whichrunthroughallhistoricalgeology,includeaperiodofmountainand

continentbuildingfollowedoneoferosionand,inturn,byanewperiodofelevation.

EarlyGeologicStudies

Observationsonearthstructureandprocessesweremadebyanumberoftheancients,

includingHerodotus,Aristotle,Lucretius,Strabo,andSeneca.Theirindividualeffortsinthe

naturalhistoryoftheearth,however,providednosustainedprogress.Theirmajorcontributionis

thattheyattributedthephenomenatheyobservedtonaturalandnotsupernaturalcauses.Manyof

theideasexpressedbythesemenwerenottoresurfaceuntiltheRenaissance.LaterLeonardoda

Vincicorrectlyspeculatedonthenatureoffossilsasremainofancientorganismsandontherole

thatriversplayintheerosionofland.Agricolamadeasystematicstudyoforedepositsinthe

early16thcentury.RobertHookeandNicolausStenobothmadepenetratingobservationsonthe

natureoffossilsandsediments.

EvolutionofModernGeology

Moderngeologybeganinthe18thcentury,whenfieldstudiesbytheFrenchmineralogist

J.E.Gultardandothersprovedmorefruitfulthanspeculation.TheGermangeologistAbraham

GottlobWerner,inspiteofthemanyerrorsofhisspecificdoctrinesandthediversionofmuchof

hisenergyintoafruitlesscontroversy(inwhichhemaintainedthatoriginofallrockswas

aqueous),performedagreatserviceforthesciencebydemonstratingthechronologicalsuccession

ofrocks.

In1795theScottishgeologistJamesHuttonlaidthetheoreticalfoundationformuchofthe

modernsciencewithhisdoctrineofuniformitarianism,firstpopularizedbytheBritishJohn

Playfair.LargelythroughtheworkofsirCharlesLyell,thisdoctrinereplacedtheopposingoneof

catastrophism.Geologyinthe19thcenturywasinfluencedalsobytheworkofCharlesDarxvin

andenrichedbytheresearchesoftheSwiss-AmericanLouisAgassiz.

Inthe20thcentury,geologyhasadvancedatanever-increasingpace.Theunravelingofthe

mysteryofatomicstructureandthediscoveryofradioactivityallowedprofoundadvancesinmany

phasesofgeologicresearch.ImportantdiscoveriesweremadeduringtheInternationalGeological

Year(1957-58),whenscientistsfrom67nationsjoinedforceininvestigatingproblemsinall

branchesofgeology.Thesystematicsurveyoftheearth'soceansbroughtradicalchangesin

conceptsofcrustalevolution.

Asaresultofnumerousflybyspacecraft,geologicalstudieshavebeenextendedtoinclude

remotesensingofotherplanetsandsatellitesinthesolarsystemandthemoon.Laboratory

analysesofrockssamplesbroughtbackfromthemoonhaveprovidedinsightintotheearlyhistory

ofnear-earthspace.On-siteanalysesofMartiansoilsamplesandphotographicmappingofits

surfacehavegivencluesaboutitscompositionandgeologichistory,includingthepossibilitythat

Marsoncehadenoughwatertoformoceans.Photographsofthemanyactivevolcanoeson

Jupiter'smoonIohaveprovidedcluesaboutearth'searlyvolcanicactivity.Geologicalstudiesalso

havebeenfurtheredbyorbitinglaboratories,suchasthesixlaunchedbetween1964inthe

OrbitingGeophysicalObservatory(OGO)seriesandthePolarOrbitingGeomagneticSurvey

(POGS)satellitelaunchedin1990;remote-imagingspacecraft,suchastheU.S.Landsatprogram

(Landsat7,launchedin1999,wasthemostrecent)andFrenchSPOTseries(SPOT4,launchedin

1988,wasthemostrecentintheprogram);andgeologicalstudiesonspaceshuttlemissions.

NewWordsandPhrases

1.mineralogy/產(chǎn)明_一n.礦物學(xué)

2.petrology/y。一n.巖石學(xué)

3.geomorphologyZn.地貌學(xué)

4.geochemistryZn.地球化學(xué)

5.geophysics/G_、n.地球物理學(xué)

6.sedimentology/_0O耳_?二,.缸O/G\n,沉積學(xué)

7.structuralgeology構(gòu)造地質(zhì)學(xué)

8.economicgeology經(jīng)濟(jì)地質(zhì)學(xué)（礦床學(xué)）

9.paleontologyZytR2「.缸o(hù)/。'n.古生物學(xué)

10.stratigraphyn.地層學(xué)

11.paleogeographyZYTGJJO/Gn.古地理學(xué)

12.Precambrian/2?,.阡n.adj.前寒紀(jì)

13.Paleozoic/Y?.?g_i_\n.adj.古生代（界）

14.MesozoicZTOu_I_O\n.adj.中生代（界）（的）

15.CenozoicZ3'n.adj.新生代（界）（的）

16.catastrophism一?.?一匚＞。?災(zāi)難論

17.remotesensingn.遙感

18.spaceshuttle航天飛機(jī)

19.Herodotus一一\（希臘歷史學(xué)家）希羅多德（約公元前485-約公元前425）

20.Werne維爾納（1750/817）德國(guó)地質(zhì)學(xué)家、礦物學(xué)家，水成論的創(chuàng)立者

21.uniformitarianismZ。一?匯_?n.均變論

22.Aristotle/?.?一。_、4\亞里士多德（公元前322-公元前384古希臘大哲學(xué)家，科學(xué)家）

23.Renaissancen.文藝復(fù)興（時(shí)期）

24.CharlesDarwin/??―一\查爾斯達(dá)爾文，英國(guó)博物學(xué)家，進(jìn)化論創(chuàng)立者

25.Landsat/n.（美國(guó)）地球資源（探測(cè)）衛(wèi)星

26.aqueous[??-；]adj.含水的，似水的

Translations&InterpretationsofdifficultSentences

1Broadcyclicalpatterns,whichrunthroughallhistoricalgeology,includeaperiodof

mountainandcontinentbuildingfollowedoneoferosionand,inturn,byanewperiodof

elevation.

貫穿著整個(gè)地史時(shí)期最主要的循環(huán)模式，包括一段時(shí)期的造山和大陸，隨后發(fā)生的侵蝕

作用，然后，是一個(gè)新時(shí)期的抬升。

2Theirindividualeffortsinthenaturalhistoryoftheearth,however,providednosustained

progress.

然而，他們的個(gè)人努力并沒(méi)有使得地球的自然歷史研究持續(xù)進(jìn)步。

3LaterLeonardodaVincicorrectlyspeculatedonthenatureoffossilsasremainofancient

organismsandontherolethatriversplayintheerosionofland.

后來(lái)，列奧納多?達(dá)?芬奇把化石的本質(zhì)作為古代生物的殘?bào)w進(jìn)行了正確的考辨反思，

并推測(cè)了河流對(duì)陸地的剝蝕作用。

Lesson2TheEarth

Ingeologyandastronomy,theEarthisthefifthlargestplanetofthesolarsystemandtheonly

planetdefinitelyknowntosupportlife.Gravitationforceshavemoldedtheearth,likeallcelestial

bodies,intoasphericalshape.However,theearthisnotanexactsphere,beingslightlyflattenedat

thepolesandbulgingattheequator,whichmeansthattheequatorialdiameterof12,756kmis

largerthanthepolardiameterof12,714km.Andthemassoftheearthis6X1024kg.Thealtitude

ofthesurfacefeaturesrangefrom11kmbelowto9kmabovesealevel,and70%ofthesurfaceis

coveredwithliquidwater,whichmakesituniqueinthesolarsystem.Additional,Earthhasan

atmospherereachingseveralhundredkmintospace,consistingof78%nitrogen,21%oxygen,1%

othergasesincludingcarbondioxideandwatervapour.Earthistheonlyplanetinoursolarsystem

tohavelargequantitiesoffreeoxygeninitsatmosphere.

Knowledgeoftheearth'sinteriorhasbeen

gatheredbythreemethods:bytheanalysisof

earthquakewavespassingthroughtheearth,by

analogywiththecompositionofmeteorites,andby

considerationoftheearth'ssize,shape,anddensity.

Researchbythesemethodsindicatesthatthe

FigureofTheEarth'sLayersearthhasazonedinterior,consistingofconcentric

shellsdifferingfromoneanotherbysize,chemicalmakeup,anddensity.TheplanetEarthismade

upofthreemainshells:theverythin,brittlecrust,themantle,andthecore;themantleandcore

areeachdividedintotwoparts.Althoughthecoreandmantleareaboutequalinthickness,the

coreactuallyformsonly15percentoftheEarth'svolume,whereasthemantleoccupies84percent.

Thecrustmakesuptheremaining1percent.

TheEarth'sCrustandtheMoho

Becausethecrustisaccessibletous,itsgeologyhasbeenextensivelystudied,andtherefore

muchmoreinformationisknownaboutitsstructureandcompositionthanaboutthestructureand

compositionofthemantleandcore.Withinthecrust,intricatepatternsarecreatedwhenrocksare

redistributedanddepositedinlayersthroughthegeologicprocessesoferuptionandintrusionof

lava,erosion,andconsolidationofrockparticles,andsolidificationandrecrystallizationofporous

rock.Bythelarge-scaleprocessofplatetectonics,abouttwelveplates,whichcontain

combinationsofcontinentsandoceanbasins,havemovedaroundontheEarth'ssurfacethrough

muchofgeologictime.Theedgesoftheplatesaremarkedbyconcentrationsofearthquakesand

volcanoes.CollisionsofplatescanproducemountainsliketheHimalayas,thetallestrangeinthe

world.Theplatesincludethecrustandpartoftheuppermantle,andtheymoveoverahot,

yieldinguppermantlezoneatveryslowratesofafewcentimetersperyear,slowerthantherateat

whichfingernailsgrow.Thecrustismuchthinnerundertheoceansthanundercontinents.

TheboundarybetweenthecrustandmantleiscalledtheMohorovicicdiscontinuity(or

Moho);itisnamedinhonorofthemanwhodiscoveredit,theCroatianscientistAndrija

Mohorovicic.Noonehaseverseenthisboundary,butitcanbedetectedbyasharpincrease

downwardinthespeedofearthquakewavesthere.TheexplanationfortheincreaseattheMohois

presumedtobeachangeinrocktypes.DrillholestopenetratetheMohohavebeenproposed,and

aSovietholeontheKolaPeninsulahasbeendrilledtoadepthof12kilometers,butdrilling

expenseincreasesenormouslywithdepth,andMohopenetrationisnotlikelyverysoon.

TheEarth'sMantle

Extendingtoadepthofc.2,900km,themantleprobablyconsistsofverydense(average

c.3.9)rockrichinironandmagnesiumminerals.Althoughtemperaturesincreasewithdepth,the

meltingpointoftherockisnotreachedbecausethemeltingtemperatureisraisedbythegreat

confiningpressure.Atdepthsbetweenc.100andc.200kminthemantle,aplasticzone,called

theasthenosphere,isfoundtooccur.Presumablytherocksinthisregionareveryclosetomelting,

andthezonerepresentsafundamentalboundarybetweenthemovingcrustalplatesoftheearth's

surfaceandtheinteriorregions.Themoltenmagmathatintrudesupwardintocrustalrocksor

issuesfromavolcanointhefromoflavamayoweitsorigintoradioactiveheatingortotherelief

ofpressureinthelowercrustanduppermantlecausedbyearthquakefaultingoftheoverlying

crustalrocks.Similarly,itisthoughtthattheheatenergyreleasedintheupperpartofmantle

hasbrokentheearth'scrustintovastplatesthatslidearoundontheplasticzone,settingup

stressesalongtheplatemarginsthatresultintheformationoffoldsandfaults.

TheEarth'sCore

Thoughtobecomposedofironandnickel,thedense(c.l1.0)coreoftheearthliesbelow

mantle.Theabruptdisappearanceofdirectcotnpressionalearthquakewaves,whichcannottravel

thoughliquids,atdepthsbelowc.2,900kmindicatesthattheouter2,200kmofthecorearemolten.

Itisthought,however,thattheinner1,260kmofthecorearesolid.Theoutercoreisthoughttobe

thesourceoftheearth'smagneticfield:Inthe'dynamotheory'advancedbyW.M.ElasserandE.

Bullard,tidalenergyorheatisconvertedtomechanicalenergyintheformofcurrentsintheliquid

core;thismechanicalenergyisthenconvertedtoelectromagneticenergy,whichweseeasthe

magneticfield.

TheEarth'sAge

theearthisestimatedtobe4.5billionto5billionyearsold,basedonradioactivedatingof

lunarrocksandmeteorites,whicharethoughttohaveformedatthesametime.Theoriginofthe

earthcontinuestobecontroversial.Amongthetheoriesastoitsorigin,themostprominentare

gravitationalcondensationhypotheses,whichsuggestthattheentiresolarsystemwasformedat

onetimeinasingleseriesofprocessesresultingintheaccumulationofdiffuseinterstellargases

anddustintoasolarsystemofdiscretebodies.Oldandnowgenerallydiscreditedtheories

invokedextraordinaryevents,suchasgravitationaldisruptionofastarpassingclosetothesunor

theexplosionofacompanionstartothesun.

NewWordsandPhrases

1.geology[O/Gn.地質(zhì)學(xué)

2.astronomy一?.?一4、n.天文學(xué)

3.solarsystemn.太陽(yáng)系

4.gravitation-。叼-?、n.地心吸力

5.celestialbody10一4」\n.天體

6.equatorn.赤道

7.altitude/n.（海拔）高度

8.meteoriteZP?-LU、n.隕石

9.concentricZadj.同心的

10.brittle/，上￡、adj.易碎的

11.intricateZadj.復(fù)雜的

12.collisionZi_夕/」.、n.碰撞

13.Himalayas20GL\n.喜馬拉雅山脈

14.Moho/「力」、n.莫霍面

Mohoroviidiscontinuity莫霍不連續(xù)面

15.asthenosphere。?―＞。\n.軟流圈

16.radioactiveZ?：…白、adj.放射性的

17.magma/n.巖漿

18.compressionalZi_+adj.壓縮的，縱（波）的

19.dynamotheory[n.（地磁場(chǎng)成因的）發(fā)電機(jī)理論

20.lunar[adj.月亮的，月球的

21.gravitationalcondensationhypotheses（天體形成的）重力凝聚假設(shè)，也稱吸積作用

22.crustalplate地殼板塊

23.interstellarZ一。心\adj.星際的

24.lava/償~一」'n.熔巖

Translations&InterpretationsofdifficultSentences

1Researchbythesemethodsindicatesthattheearthhasazonedinterior,consistingof

concentricshellsdifferingfromoneanotherbysize,chemicalmakeup,anddensity.

通過(guò)這些方法研究表明地球的內(nèi)部是由同心圈層組成，這些圈層的大小，化學(xué)組成以及

密度互不相同。

2Althoughthecoreandmantleareaboutequalinthickness,thecoreactuallyformsonly15

percentoftheEarth'svolume,whereasthemantleoccupies84percent.

雖然地核和地幔在重量上是近似均等的，地核只占地球體積的大約15%,而地幔占了

84%o

3Withinthecrust,intricatepatternsarecreatedwhenrocksareredistributedanddepositedin

layersthroughthegeologicprocessesoferuptionandintrusionoflava,erosion,andconsolidation

ofrockparticles,andsolidificationandrecrystallizationofporousrock.

當(dāng)如巖漿噴發(fā)和侵入，侵蝕，巖石顆粒的固結(jié)以及多孔巖石的凝固和重結(jié)晶等地質(zhì)過(guò)程

作用于地殼時(shí)，創(chuàng)造了地殼內(nèi)復(fù)雜的格局。

4Althoughtemperaturesincreasewithdepth,themeltingpointoftherockisnotreached

becausethemeltingtemperatureisraisedbythegreatconfiningpressure.

雖然隨著深度的增加溫度升高，但由于熔點(diǎn)隨著壓力的增加而升高，溫度并未達(dá)到巖石

的熔點(diǎn)。

5Themoltenmagmathatintrudesupwardintocrustalrocksorissuesfromavolcanointhe

fromoflavamayoweitsorigintoradioactiveheatingortotherelieffpressureinthelowercrust

anduppermantlecausedbyearthquakefaultingoftheoverlyingcrustalrocks.

上覆地殼巖石的地震斷層會(huì)導(dǎo)致下地殼和上地幔的熱輻射或解壓,這可能是是熔融的巖

漿侵入地表巖石或火山噴發(fā)熔巖的主要原因。

6Theoutercoreisthoughttobethesourceoftheearth9smagneticfield:Inthe4dynamo

theory,advancedbyW.M.ElasserandE.Bullard,tidalenergyorheatisconvertedtomechanical

energyintheformofcurrentsintheliquidcore;thismechanicalenergyisthenconvertedto

electromagneticenergy,whichweseeasthemagneticfield.

外地核被認(rèn)為是地球磁場(chǎng)的來(lái)源，根據(jù)W.M.ElasserandE.Bullard的“地磁場(chǎng)理論”，潮

汐能或者熱可以轉(zhuǎn)化為液芯中的機(jī)械能流，機(jī)械能再轉(zhuǎn)化為電磁能，也就是我們所知道的磁

場(chǎng)。

Lesson3EarthquakeandVolcanoes

Earthquake

Earthquakeistremblingorshakingmovementoftheearth'ssurface.Mostearthquakesare

minortremors.Largerearthquakesusuallybeginwithslighttremorsbutrapidlytaketheformof

oneormoreviolentshocks,andendinvibrationsofgraduallydiminishingforcecalled

aftershocks.Thesubterraneanpointoforiginofanearthquakeiscalleditsfocus;thepointonthe

surfacedirectlyabovethefocusistheepicenter.Themagnitudeandintensityofanearthquakeis

determinedbytheuseofscales,e.g.,theRichterscaleandMercalliscale.

Mostearthquakesarecausallyrelatedtocompressionalortensionalstressesbuiltupatthe

marginsofthehugemovinglithosphericplatesthatmakeuptheearth'surface.Theimmediate

causeofmostshallowearthquakesisthesuddenreleaseofstressalongafault,orfractureinthe

earth'scrusfresultinginmovementoftheopposingblocksofrockpastoneanother.These

movementscausevibrationstopassthroughandaroundtheearthinwavefrom,justasripplesare

generatedwhenapebbleisdroppedintowater.Volcaniceruption,rockfalls,landslides,and

explosionscanalsocauseaquake,butmostoftheseareofonlylocalextent.

ThereareseveraltypesofearthquakewavesincludingP,orprimary,waves,whichare

compressionalandtravelfastest;andS,orsecondary,waves,whicharetransverse,i.e.,theycause

theearthtovibrateperpendicularlytothedirectionoftheirmotion.Surfacewavesconsistof

severalmajortypesandarecalledL,orlong,waves.SincethevelocitiesofthePandSwavesare

affectedbythechangesinthedensityandrigidityofthematerialthroughwhichtheypass,the

boundariesbetweentheregionsoftheearthknownasthecrust,mantle,andcorehavebeen

discernedbyseismologists,scientistswhodealwiththeanalysisandinterpretationofearthquake

waves.SeismographsareusedtorecordP,SandL'waves.ThedisappearanceofSwavesbelow

depthsof2,900kmindicatesthatatleasttheouterpartoftheearth'scoreisliquid.

Theeffectsofanearthquakearestrongestinabroadzonesurroundingtheepicenter.The

extentofearthquakevibrationandsubsequentdamagetoaregionispartlydependenton

characteristicsoftheground.Forexample,earthquakevibrationslastlongerandareofgreater

waveamplitudesinunconsolidatedsurfacematerial,suchaspoorlycompactedfillorriver

deposits;bedrockareasreceivefewereffects.Theworstdamageoccursindenselypopulated

urbanareaswherestructuresarenotbuilttowithstandintenseshaking.There,Lwavescan

producedestructivevibrationsinbuildingsandbreakwaterandgaslines,startinguncontrollable

fires.

Damageandlossoflifesustainedduringanearthquakeresultfromfallingstructuresand

flyingglassandobjects.Flexiblestructuresbuiltonbedrockaregenerallymoreresistantto

earthquakedamagethanrigidstructuresbuiltonloosesoil.Incertainareas,anearthquakecan

triggermudslides,whichslipdownmountainslopesandcanburyhabitationsbelow.Asubmarine

earthquakecancausetsunamis,damagingwavesthatrippleoutwardfromtheearthquake

epicenterandinundatecoastalcities.

Onaverageabout1,000earthquakeswithintensitiesof5.0orgreaterarerecordedeachyear.

Greatearthquakes(intensity8.()orhigher)occuronceayear,majorearthquakes(intensity7.0-7.9)

occur18timesayear,strongearthquakes(intensity6.0-6.9)10timesamonth,andmoderate

earthquakes(intensity5.0-5.9)morethantwiceaday.Becausemostoftheseoccurunderthe

oceanorinunderpopulatedareas,theypassunnoticedbyallbutseismologists.

Volcanoes

Volcanoesareventsorfissuresintheearth'scrustthoughwhichgases,moltenrock,orlava,

andsolidfragmentsaredischarged.Thetermvolcanoiscommonlyappliedbothtotheventandto

theconicalmountainbuiltuparoundtheventbytheeruptedrockmaterials.Volcanoesare

describedasactive,dormant,orextinct.Thesoilresultingfromdecompositionofvolcanic

materialsisextremelyfertile,andtheashitselfisagoodpolishingandcleansingagent.

Volcanoesarefoundinassociationwithmidoceanridgesystemsandalongconvergentplate

boundaries,suchasaroundthePacificOcean's'RingofFire',theringofplateboundaries

associatedwithvolcanicislandarcsandoceantrenchessurroundingthePacificOcean.Isolated

volcanoesalsoforminthemidoceanareaofthePacificapparentlyunrelatedtocrustalplate

boundaries.Theseseamountsandvolcanicislandchains,suchastheHawaiianchain,mayform

fromrisingmagmaregionscalledhotspots.

Morethan500volcanoesknowntohaveeruptedontheearth'ssurfacesincehistorictimes,

andmanymorehaveeruptedontheoceanfloorunobservedbyhumans.Fiftyvolcanoeshave

eruptedintheUnitedStates,whichranksthird,behindIndonesiaandJapan,inthenumberof

historicallyactivevolcanoes.Oftheworld'sactivevolcanoes,morethanhalfarefoundaroundthe

perimeterofthePacific,aboutathirdonmidoceanicislandsandinanarcalongthesouthofthe

Indonesianisland,andaboutatenthintheMediterraneanarea,Africa,andAsiaMinor.

Evidenceofextraterrestrialvolcanicactivityalsohasbeenfound.Spaceprobeshavedetected

theremnantsofancienteruptionsonearth'smoon,Mars,andMercury;theseprobablyoriginated

billionsofyearsago,sincethesebodiesarenolongercapableofvolcanicactivity.Triton(a

satelliteofNeptune),Io(asatelliteofJupiter),andVenusaretheonlybodiesinthesolarsystem

besidesearththatareknowntobevolcanicallyactive.Thevolcanicprocessesthatoccurinthe

outerportionofthesolarsystemareverydifferentfromthoseintheinnerpart.Eruptionsonearth,

Venus,Mercury,andMarsareofrockymaterialandaredrivenbyinternalheat.lo'seruptionsare

probablysulfurcompoundsdrivenbytidalinteractionswithJupiter.Triton'seruptionsareofvery

volatilecompounds,suchasmethaneornitrogen,drivenbyseasonalheatingfromthesun.

Terrestrialvolcaniceruptionsmaytakeoneormoreoffourchiefforms,orphases,knownas

Hawaiian,Strombolian,Vulcanian,andPelean.IntheHawaiianphasethereisarelativelyquiet

effusionofbasalticlavaunaccompaniedbyexplosionsortheejectionoffragments;theeruptions

ofMaunaLoaontheislandofHawaiiaretypical.TheStrombolianphasederivesitsnamefrom

thevolcanoStromboliintheLipari,orAeolian,Islands,NofSicily.Itappliestocontinuousbut

milddischargesinwhichviscouslavaisemittedinrecurringexplosion;theejectionof

incandescentmaterialproduceluminousclouds.Amoreexplosivevolcaniceruptionisthe

Vulcanian,wherethemagma(lavabeforeemission)accumulatesintheupperleveloftheventbut

isblockedbyahardenedplugoflavathatformsbetweenconsecutiveexplosions.Whenthe

explosivegaseshavereachedacriticalpressurewithinthevolcano,massesofsolidandliquid

rockeruptintotheairandcloudsofvaporformoverthecrater.ThePelean,derivedformMont

Pelee,isthemostviolent,emittingfineash;hot,gas-chargedfragmentsoflava;andsuperheated

steaminanincandescent'cloud'thattravelsdownhillatgreatspeed.Eruptionsareoften

accompaniedbytorrentialrainscausedbythecondensationofsteam.Theeruptedfragmentsvary

insize,includingminuteparticlesofvolcanicdustandash,lapilli(cinderorpellets),bombs

(roundedorellipsoidalmassesofhardenedmagma),andhugemassescalledblocks.

NewWordsandPhrases

1.aftershock?.Xn.余震

2.subterranean_。。?門—專、adj.地下的

3.RichterscaleZn.里氏震級(jí)

4.Mercalliscale/干o金?麥加利震級(jí)

5.compressionalstress壓應(yīng)力

6.tensionalstress張應(yīng)力

7.focus/n.焦點(diǎn)，焦距，(地震的)震源

8.epicenter/n.震中

9.rigidityn.剛度

10.seismologist/孑"6_0/，\n.地震學(xué)家

11.seismographZJ-?°+i_O-=^>\n.地震儀

12.waveamplitudeZ,.阡y/JU?0、n.波幅

13.bedrocki/$OO\n.巖基

14.mudslide/工1Gn.泥石流

15.tsunami?金?n.海嘯

16.inundate?/:0cV.淹沒(méi)

17.volcanon.火山

18.dormantZO"?：?一\adj.休眠的

19.convergentplateboundary會(huì)聚板塊邊緣

20.oceantrench海溝

21.perimeter_阡％_\n.周長(zhǎng)，周邊

22.extralerreslrialV一adj.地球外的，宇宙的

24.