continental drift and plate - pb drift plate...continental drift and plate 2 march 25, 2013...

Download Continental Drift and Plate   - PB  drift plate...Continental Drift and Plate   2 March 25, 2013 Continental Drift According to the theory, about 250 million years ago, the continents were

Post on 06-Apr-2018

218 views

Category:

Documents

4 download

Embed Size (px)

TRANSCRIPT

  • ContinentalDriftandPlateTectonics.notebook

    1

    March25,2013

    Continental Drift and Plate Tectonics

    In1912,aGermanscientistnamedAlfredWegenernoticedthattheEarth'scontinentsseemedtofittogetherlikepuzzlepieces.Heproposedthetheoryofcontinentaldrifttoexplainwhathesaw.

  • ContinentalDriftandPlateTectonics.notebook

    2

    March25,2013

    ContinentalDrift

    Accordingtothetheory,about250millionyearsago,thecontinentswereonceapartofasupercontinent.ThesupercontinentwasknownasPangaea,whichmeans"allland."

    About180millionyearsago,Pangaeasplitintotwohugecontinents:LaurasiaandGondwana.Thesecontinentsthenstartedbreakingapartanddriftinguntiltheyreachedtheircurrentpositionstoday.

    EvidencetoSupportContinentalDrift1)SimilarFossils2)TypesofRocks3)GlaciationPatternsonsurfacesthatwerewidespread

    1)Similarfossils(thatcouldnothavetraveledacrossentireoceans)werefoundonseveraldifferentlandmasses.

    Example:Mesosaurus,afreshwaterreptile,wasfoundinSouthAmericaandSouthernAfrica.

  • ContinentalDriftandPlateTectonics.notebook

    3

    March25,2013

    EvidencetoSupportContinentalDrift

    2)Rocktypesthatarefoundoncontinentsthatareoceansapartarefurtherevidencetosupportcontinentaldrift.

    Example:MatchingmountainrangesinNorthAmericaandGreatBritian/Scandinavia.

    3)Glacialdepositshavebeenfoundinareasthattodayhavetropicalclimates,alsosuggestingthatthecontinentswereonceconnected.

    ContinentaldriftandthechangestotheEarthcanbeexplainedbyplatetectonics.ThetheoryofplatetectonicsstatesthatEarth'slithosphere(land)isbrokenintolargesectionscalledtectonicplatesthatmoveandchangepositionovertime.

    Continentalplatessupportthelandwhileoceanicplatessupporttheoceans.

  • ContinentalDriftandPlateTectonics.notebook

    4

    March25,2013

    Tectonicplatesfloatonadense,moltenlayerofsemifluidrockknownastheasthenosphere.Temperaturedifferencesintheasthenospherecauseslowmovingcurrents.

    Themotionofthecurrentscausestheplatesabovetomoveaswell.Wherecurrentsarerising,platesarepushedapart.Wherecurrentsaresinking,platesarepulledtogether.

    PlateTectonics

    TypesofPlateBoundariesPlateboundariesarewheretectonicplatestouch.

    ConvergentBoundaries:Areformedwheretheplatesconvergeormovetogether.Oftencausemountainstoform.

    DivergentBoundaries:Areformedwheretheplatesdivergeormoveapart.Createmidoceanridges,newland,orcanproducevolcanoesonland.

    TransformFaultBoundaries:occurwheretwoplatesgrindpasteachother.Causesearthquakes.

    Thetypeofboundarydependsonhowthetectonicplatesmoverelativetooneanother.

  • ContinentalDriftandPlateTectonics.notebook

    5

    March25,2013

    ConvergentBoundaries

    OceanicContinental:Becauseitisdenser,theoceanicplateissubductedbeneathacontinentalplate,createsmountainrangeex.AndesMountainrangeinSouthAmerica

    OceanicOceanic:oneoceanicplateissubductedbeneathanotheroceanicplate,createsatrench,underseavolcanoes>islandsEx.theAleutianislandsinAlaskawereformedthisway

    ContinentalContinental:twoplateswithcontinentalcrustcollideandpushupward,createsmountainranges,sometimesearthquakes.ex.Himalayanmountains

    DrawingPlateBoundaries

    imagefromtasaclips.com/illustrations.html

    Thesubductionzoneiswherethedenseroceaniccrustsinksbelowthecontinentalplate.Oldoceancrustgetspusheddownintotheasthenosphere,whereitisremeltedandrecycled.

    http://geology.com/nsta/

  • ContinentalDriftandPlateTectonics.notebook

    6

    March25,2013

    DivergentPlateBoundariesWheretwoplatesseparateandmoveapart.Wheretwooceanicplatesaremovingapart,newoceanfloorformsasmagmarisestowardthesurfaceandhardens.Theoceansgetwider,andalongchainofvolcanicmountains,calledthemidoceanridge,formsalongtheboundary.Ex.themidAtlanticRidge

    Whentwocontinentalplatesseparate,aridge,orrift,isformed.Streamsandriversflowintotheriftvalleytoformalonglinearlake.Iftheriftdropsbelowsealevel,oceanwaterstoflowin,creatinganarrow,shallowsea.Iftheriftgrowsdeeperandwider,anewoceanbasincouldbeproduced.Ex.TheEastAfricaRiftValley

    TransformFaultBoundariesTectonicplatesslidepasteachotherhorizontally.Becausetheplateshaveirregularedges,theygrindandjerk,producingearthquakes.

    Ex.SanAndreasfaultinCalifornia

  • ContinentalDriftandPlateTectonics.notebook

    7

    March25,2013

    ThreeTypesofBoundaries:

    Labeltheboxesbelowtoindicatethemovementofthethreetypesofboundaries.

    Transform

    Convergent

    Divergent

    Typically,platesonlymoveafewcentimetersperyear,butcanstillcauseearthquakes,volcanoes,andtheformationofmountains.

    TheDecember26,2004,IndonesianearthquakethatcauseddevastatingtsunamisallaroundtheIndianOceanandSouthAsiawasunusualbecausetheplatesmoved10m(33ft)horizontallyand45m(1316ft)vertically!

    Ithastaken169,000,000years(169millionyears)forNewYorkandAfricatoreachtheircurrentlocations,iftheyaremovingapartat4cmayear:

    6760km1000m100cm=676,000,000cm1km 1m

    676,000,000cm/4cmperyear=169,000,000years

    Page 1Page 2Page 3Page 4Page 5Page 6Page 7