2015考研英语阅读真题 小火山活跃区

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1、http://www.kaoyan365.cn　　Scatteredaroundtheglobearemorethan100smallregionsofisolatedvolcanicactivityknowntogeologistsashotspots.Unlikemostoftheworld’svolcanoes,theyarenotalwaysfoundattheboundariesofthegreatdriftingplatesthatmakeuptheearth’ssurface;onthecontrary,manyofthemliedeepin

2、theinteriorofaplate.Mostofthehotspotsmoveonlyslowly,andinsomecasesthemovementoftheplatespastthemhaslefttrailsofdeadvolcanoes.Thehotspotsandtheirvolcanictrailsaremilestonesthatmarkthepassageoftheplates.　　Thattheplatesaremovingisnotbeyonddispute.AfricaandSouthAmerica,forexample,arem

3、ovingawayfromeachotherasnewmaterialisinjectedintotheseafloorbetweenthem.Thecomplementarycoastlinesandcertaingeologicalfeaturesthatseemtospantheoceanareremindersofwherethetwocontinentswereoncejoined.Therelativemotionoftheplatescarryingthesecontinentshasbeenconstructedindetail,butth

4、emotionofoneplatewithrespecttoanothercannotreadilybetranslatedintomotionwithrespecttotheearth’sinterior.Itisnotpossibletodeterminewhetherbothcontinentsaremovinginoppositedirectionsorwhetheronecontinentisstationaryandtheotherisdriftingawayfromit.Hotspots,anchoredinthedeeperlayersof

5、theearth,providethemeasuringinstrumentsneededtoresolvethequestion.FromananalysisofthehotspotpopulationitappearsthattheAfricanplateisstationaryandthatithasnotmovedduringthepast30millionyears.　　Thesignificanceofhotspotsisnotconfinedtotheirroleasaframeofreference.Itnowappearsthatthey

6、alsohaveanimportantinfluenceonthegeophysicalprocessesthatpropeltheplatesacrosstheglobe.Whenacontinentalplatecometorestoverahotspot,thematerialrisingfromdeeperlayercreatesabroaddome.Asthedomegrows,itdevelopsseedfissures(cracks);inatleastafewcasesthecontinentmaybreakentirelyalongsom

7、eofthesefissures,sothatthehotspotinitiatestheformationofanewocean.Thusjustasearliertheorieshaveexplainedthemobilityofthecontinents,sohotspotsmayexplaintheirmutability(inconstancy).　　译文中公考研http://www.kaoyan365.cnhttp://www.kaoyan365.cn　　地球上散落分布着100多个互不相连的小火山活跃区，地质学家称之为热点。与地球上大多数火山不

8、同的是，它们并不总是在构成地球表面的巨大漂流板块之间的连接处上出现