Earth’sStructure-TeacherWeb：地球的结构teacherweb

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1、Earth’sStructureThelayersofEarthEarthisdividedinto3layersbasedonchemicalcomposition.Core:Densemetalliccenter,madeupofmainlymetaliron.Mantle:Liquidmiddlelayermadeupofsilicon,oxygenandmagnesium.Crust:Thesolidouterlayermadeupofsilicon,oxygenandaluminum.ContinentalandOceanicCrustTherear

2、etwotypesofcrust:Continental:isthickerOceanic:isthinnerandheavier.Comparedtotheotherlayers,bothtypesofcrustarerocky,thinandfractured.ThePhysicalStructureofEarthEarthisdividedintofivelayersbasedonphysicalproperties.LithosphereAsthenosphereMesosphereOutercoreInnercoreLithosphereLithos

3、phere:coolrigidlayer,madeupofthecrustandupperlayerofthemantle.Lithosphereisdividedintopiecescalledtectonicplates.Asthenosphere2.AsthenosphereBelowthelithosphere.Madeupofslowflowingsolidrock.Themovingrockallowsfortectonicplatestomove.PhysicalStructurecont.3.Mesosphere:Slowflowinglaye

4、rbeneaththeAsthenosphere4.Outercore:LayerofliquidIronandNickel.5.Innercore:Solidironandnickel,temperatureisestimatedtobebetween4000ºCto5000ºCMappingEarth’sInteriorHowcanweknowsomuchaboutEarth’sinteriorifnoonehaseverdrilledthroughthecrust?Earthquakesproduceseismicwaves,andtravelthrum

5、aterialsatdifferentspeeds.ScientistsusethesewavestodeterminethedensityofeachofEarth'slayersContinentalDriftInthe1900’s,ScientistAlfredWagner,viewedthecontinentsaspuzzlepieces.Hadahypothesisthatourcontinentsusedtobeonelargecontinent.HenamedhishypothesistheContinentalDriftTheory.Evide

6、nceforContinentalDriftFossilsofsameplantcanbefoundoncontinentsthatarefarfromeachother.Locationofmountainrangeswithsimilarrocksshowapattern.TheBreakupofPangaeaAsinglecontinentPangaea(manythousandsofyearsago).Splitintotwocontinents–LaurasiaandGondwana(thousandsofyearsago).Splitintotod

7、ay'scontinents.Continentssometimescollided,formingmountainrangesandvolcanoes.Sea-FloorSpreading.WhenWagnerintroducedhishypothesis,manyscientistsdidnotacceptitbecausethestrengthneededtomoveEarth’scrustseemedimpossible.Inthe1960’sScientiststudyingtheoceanfloordiscoveredidenticalpatter

8、nsofmagnetismonboth