What is Tectonic Shift? - National Ocean Service

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The Earth is in a constant state of change. Earth's crust, called the lithosphere, consists of 15 to 20 moving tectonic plates. HomeOceanFactsWhatisTectonicShift? WhatisTectonicShift? TectonicshiftisthemovementoftheplatesthatmakeupEarth’scrust. TheEarthismadeupofroughlyadozenmajorplatesandseveralminorplates. TheEarthisinaconstantstateofchange.Earth’scrust,calledthelithosphere,consistsof15to20movingtectonicplates.Theplatescanbethoughtoflikepiecesofacrackedshellthatrestonthehot,moltenrockofEarth’smantleandfitsnuglyagainstoneanother.Theheatfromradioactiveprocesseswithintheplanet’sinteriorcausestheplatestomove,sometimestowardandsometimesawayfromeachother.Thismovementiscalledplatemotion,ortectonicshift. Ourplanetlooksverydifferentfromthewayitdid250millionyearsago,whentherewasonlyonecontinent,calledPangaea,andoneocean,calledPanthalassa.AsEarth’smantleheatedandcooledovermanymillennia,theoutercrustbrokeupandcommencedtheplatemotionthatcontinuestoday. Thehugecontinenteventuallybrokeapart,creatingnewandever-changinglandmassesandoceans.HaveyouevernoticedhowtheeastcoastofSouthAmericalookslikeitwouldfitneatlyintothewestcoastofAfrica?That’sbecauseitdid,millionsofyearsbeforetectonicshiftseparatedthetwogreatcontinents. Earth’slandmassesmovetowardandawayfromeachotheratanaveragerateofabout0.6inchayear.That’sabouttheratethathumantoenailsgrow!Someregions,suchascoastalCalifornia,movequitefastingeologicalterms—almosttwoinchesayear—relativetothemorestableinteriorofthecontinentalUnitedStates.Atthe“seams”wheretectonicplatescomeincontact,thecrustalrocksmaygrindviolentlyagainsteachother,causingearthquakesandvolcanoeruptions.TherelativelyfastmovementofthetectonicplatesunderCaliforniaexplainsthefrequentearthquakesthatoccurthere. SearchOurFacts GetSocial MoreInformation NationalGeodeticSurvey Whatisgeodesy? Whatisthegeoid? "CopingwithTectonicShift,"TheAmericanSurveyor Didyouknow? Measuringthemotionoftectonicplatesispartofthescienceofgeodesy.TodefinetheshapeoftheEarth,NOAA’sNationalGeodeticSurvey,partoftheNationalOceanService,usesavarietyoftechniquestomeasuretheplanet’srateofrotation,itsplatemotion,andthewaysthatgravityaffectscertainscientificprocesses.   LearnMore Lastupdated:02/26/21 Author:NOAA Howtocitethisarticle ContactUs

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