考研优美英语作文的背诵036
<p> <span word="The">The</span> <span word="theory">theory</span> <span word="of">of</span> <span word="plate">plate</span> <span word="tectonics">tectonics</span> <span word="describes">describes</span> <span word="the">the</span> <span word="motions">motions</span> <span word="of">of</span> <span word="thelithosphere">thelithosphere</span>, <span word="the">the</span> <span word="comparatively">comparatively</span> <span word="rigid">rigid</span> <span word="outer">outer</span> <span word="layer">layer</span> <span word="of">of</span> <span word="the">the</span> <span word="Earth">Earth</span> <span word="thatincludes">thatincludes</span> <span word="all">all</span> <span word="the">the</span> <span word="crust">crust</span></p><p> <span word="and">and</span> <span word="part">part</span> <span word="of">of</span> <span word="the">the</span> <span word="underlying">underlying</span> <span word="mantle">mantle</span>.<span word="The">The</span> <span word="lithosphere">lithosphere</span> <span word="is">is</span> <span word="divided">divided</span> <span word="into">into</span> <span word="a">a</span> <span word="few">few</span> <span word="dozen">dozen</span> <span word="plates">plates</span> <span word="of">of</span> <span word="various">various</span> <span word="sizes">sizes</span> <span word="andshapes">andshapes</span>, <span word="in">in</span> <span word="general">general</span> <span word="the">the</span> <span word="plates">plates</span> <span word="are">are</span> <span word="in">in</span> <span word="motion">motion</span> <span word="with">with</span> <span word="respect">respect</span> <span word="to">to</span> <span word="one">one</span> <span word="another">another</span>. <span word="Amid">Amid</span>-<span word="ocean">ocean</span> <span word="ridge">ridge</span> <span word="is">is</span> <span word="a">a</span> <span word="boundary">boundary</span> <span word="between">between</span> <span word="plates">plates</span> <span word="where">where</span> <span word="new">new</span> <span word="lithosphericmaterial">lithosphericmaterial</span> <span word="is">is</span> <span word="injected">injected</span> <span word="from">from</span> <span word="belows">belows</span>. <span word="As">As</span> <span word="the">the</span> <span word="plates">plates</span> <span word="diverge">diverge</span> <span word="from">from</span> <span word="a">a</span> <span word="mid">mid</span>-<span word="oceanridge">oceanridge</span> <span word="they">they</span> <span word="slide">slide</span> <span word="on">on</span> <span word="a">a</span> <span word="more">more</span> <span word="yielding">yielding</span></p><p> <span word="layer">layer</span> <span word="at">at</span> <span word="the">the</span> <span word="base">base</span> <span word="of">of</span> <span word="the">the</span> <span word="lithosphere">lithosphere</span>.<span word="Since">Since</span> <span word="thesize">thesize</span> <span word="of">of</span> <span word="the">the</span> <span word="Earth">Earth</span> <span word="is">is</span> <span word="essentially">essentially</span> <span word="constant">constant</span>, <span word="new">new</span> <span word="lithosphere">lithosphere</span> <span word="can">can</span> <span word="be">be</span> <span word="created">created</span> <span word="at">at</span> <span word="the">the</span> <span word="mid">mid</span>-<span word="ocean">ocean</span> <span word="ridges">ridges</span> <span word="only">only</span> <span word="if">if</span> <span word="an">an</span> <span word="equal">equal</span> <span word="amount">amount</span> <span word="of">of</span> <span word="lithospheric">lithospheric</span> <span word="material">material</span> <span word="isconsumed">isconsumed</span> <span word="elsewhere">elsewhere</span>. <span word="The">The</span> <span word="site">site</span> <span word="of">of</span> <span word="this">this</span> <span word="destruction">destruction</span> <span word="is">is</span> <span word="another">another</span> <span word="kind">kind</span> <span word="of">of</span> <span word="plateboundary">plateboundary</span>: <span word="a">a</span> <span word="subduction">subduction</span> <span word="zone">zone</span>. <span word="There">There</span> <span word="one">one</span> <span word="plate">plate</span> <span word="dives">dives</span> <span word="under">under</span> <span word="the">the</span> <span word="edge">edge</span> <span word="of">of</span> <span word="anotherand">anotherand</span> <span word="is">is</span> <span word="reincorporated">reincorporated</span> <span word="into">into</span> <span word="the">the</span> <span word="mantle">mantle</span>. <span word="Both">Both</span> <span word="kinds">kinds</span> <span word="of">of</span> <span word="plate">plate</span> <span word="boundary">boundary</span> <span word="areassociated">areassociated</span> <span word="with">with</span> <span word="fault">fault</span> <span word="systems">systems</span>, <span word="earthquakes">earthquakes</span> <span word="and">and</span> <span word="volcanism">volcanism</span>, <span word="but">but</span> <span word="thekinds">thekinds</span> <span word="of">of</span> <span word="geologic">geologic</span> <span word="activity">activity</span> <span word="observed">observed</span> <span word="at">at</span> <span word="the">the</span> <span word="two">two</span> <span word="boundaries">boundaries</span> <span word="are">are</span> <span word="quitedifferent">quitedifferent</span>.</p><p> <span word="The">The</span> <span word="idea">idea</span> <span word="of">of</span> <span word="sea">sea</span>-<span word="floor">floor</span> <span word="spreading">spreading</span> <span word="actually">actually</span> <span word="preceded">preceded</span> <span word="thetheory">thetheory</span> <span word="of">of</span> <span word="plate">plate</span> <span word="tectonics">tectonics</span>. <span word="In">In</span> <span word="its">its</span> <span word="original">original</span> <span word="version">version</span>, <span word="in">in</span> <span word="the">the</span> <span word="early">early</span> 1960<span word="s">s</span>, <span word="itdescribed">itdescribed</span> <span word="the">the</span> <span word="creation">creation</span> <span word="and">and</span> <span word="destruction">destruction</span> <span word="of">of</span> <span word="the">the</span> <span word="ocean">ocean</span> <span word="floor">floor</span>, <span word="but">but</span> <span word="it">it</span> <span word="did">did</span> <span word="notspecify">notspecify</span> <span word="rigid">rigid</span> <span word="lithospheric">lithospheric</span> <span word="plates">plates</span>. <span word="The">The</span> <span word="hypothesis">hypothesis</span> <span word="was">was</span> <span word="substantiated">substantiated</span> <span word="soonafterward">soonafterward</span> <span word="by">by</span> <span word="the">the</span> <span word="discovery">discovery</span> <span word="that">that</span> <span word="periodic">periodic</span> <span word="reversals">reversals</span> <span word="of">of</span> <span word="the">the</span> <span word="Earths">Earths</span> <span word="magneticfield">magneticfield</span> <span word="are">are</span> <span word="recorded">recorded</span> <span word="in">in</span> <span word="the">the</span> <span word="oceanic">oceanic</span> <span word="crust">crust</span>. <span word="As">As</span> <span word="magma">magma</span> <span word="rises">rises</span> <span word="under">under</span> <span word="the">the</span> <span word="mid">mid</span>-<span word="ocean">ocean</span> <span word="ridge">ridge</span>, <span word="ferromagnetic">ferromagnetic</span> <span word="minerals">minerals</span> <span word="in">in</span> <span word="the">the</span> <span word="magma">magma</span> <span word="becomemagnetized">becomemagnetized</span> <span word="in">in</span> <span word="the">the</span> <span word="direction">direction</span> <span word="of">of</span> <span word="the">the</span> <span word="geomagnetic">geomagnetic</span> <span word="field">field</span>. <span word="When">When</span> <span word="the">the</span> <span word="magma">magma</span> <span word="coolsand">coolsand</span> <span word="solidifies">solidifies</span>, <span word="the">the</span> <span word="direction">direction</span> <span word="and">and</span> <span word="the">the</span> <span word="polarity">polarity</span> <span word="of">of</span> <span word="the">the</span> <span word="field">field</span> <span word="are">are</span> <span word="preserved">preserved</span> <span word="inthe">inthe</span> <span word="magnetized">magnetized</span> <span word="volcanic">volcanic</span> <span word="rock">rock</span>. <span word="Reversals">Reversals</span> <span word="of">of</span> <span word="the">the</span> <span word="field">field</span> <span word="give">give</span> <span word="rise">rise</span> <span word="to">to</span> <span word="a">a</span> <span word="seriesof">seriesof</span> <span word="magnetic">magnetic</span></p>
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