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1、http://bailiedu.com托福听力TPO1原文Lecture2下面就让小编来为大家介绍一下托福听力TPO1原文中Lecture2的文本内容吧，大家要好好把握，这些都是非常有价值的材料，希望能够给准备托福听力的同学带来帮助。TPO1Lecture2GeologyListentopartofalectureinageologyclass.ProfessorOk,let’sgetstarted.Great.TodayIwanttotalkaboutawayinwhichweareabletodeterminehowoldapieceofland,orsomeothergeologicf
2、eatureis-datingtechniques.I’mgoingtotalkaboutaparticulardatingtechnique.Why?Gooddatingiskeytogoodanalysis.Inotherwords,ifyouwanttoknowhowalandformationwasformed,thefirstthingyouprobablywanttoknowishowolditis.It’sfundamental.Uh…TaketheGrandCanyonforinstance.Now,wegeologiststhoughtwehadaprettygoodide
3、aofhowtheGrandCanyoninthesouthwesternUnitedStateswasformed.Weknewthatitwasformedfromsandstonethatsolidifiedsomewherebetween150and300millionyearsago.Beforeitsolidified,itwasjustregularsand.Essentiallyitwaspartofavastdesert.Anduntiljustrecently,mostofusthoughtthesandhadcomefromanancientmountainrangef
4、airlyclosebythatflattenedoutovertime.That’sbeentheconventionalwisdomamonggeologistsforquitesometime.Butnowwe’velearnedsomethingdifferent,andquitesurprising,usingatechniquecalledUranium-LeadDating.IshouldsaythatUranium-LeadDatinghasbeenaroundforquiteawhile.Buttherehavebeensomerecentrefinements.Iwill
5、getintothisinaminute.Anyway,Uranium-LeadDatinghasproducedsomesurprises.TwogeologistsdiscoveredthatabouthalfofthesandfromtheGrandCanyonwasactuallyoncepartoftheAppalachianMountains.That’sreallyeye-openingnews,sincetheAppalachianMountainRangeis,ofcourse,thousandsofkilometerstotheeastoftheGrandCanyon.S
6、oundsprettyunbelievable,right?Ofcourse,theobviousquestionishowdidthatsandendupsofarwest?Thetheoryisthathugeriversandwindcarriedthesandwestwhereitmixedinwiththesandthatwasalreadythere.Well,thiswasaprettyrevolutionaryfinding.Um…anditwasbasicallybecauseofUranium-LeadDating.Why?Well,aseveryoneinthiscla
7、ssshouldknow,weusuallylookatthegraintypewithinsandstone,meaningtheactualparticlesinthesandstone,todeterminewhereitcamefrom.Youcandootherthingstoo,http://bailiedu.comlikelookatthewindorwaterthatbroughtthegra
