考研英语作文155篇Plate Tectonics Sea
<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="the">the</span> <span word="lithosphere">lithosphere</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="that">that</span> <span word="includes">includes</span> <span word="all">all</span> <span word="the">the</span> <span word="crust">crust</span> <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="and">and</span> <span word="shapes">shapes</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="A">A</span> <span word="mid">mid</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="lithospheric">lithospheric</span> <span word="material">material</span> <span word="is">is</span> <span word="injected">injected</span> <span word="from">from</span> <span word="below">below</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="ocean">ocean</span> <span word="ridge">ridge</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> <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>.</p><p> <span word="Since">Since</span> <span word="the">the</span> <span word="size">size</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="is">is</span> <span word="consumed">consumed</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="plate">plate</span> <span word="boundary">boundary</span>: <span word="a">a</span> <span word="seduction">seduction</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="another">another</span> <span word="and">and</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="are">are</span> <span word="associated">associated</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="the">the</span> <span word="kinds">kinds</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="quite">quite</span> <span word="different">different</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="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="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="it">it</span> <span word="described">described</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="not">not</span> <span word="specify">specify</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="soon">soon</span> <span word="afterward">afterward</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="magnetic">magnetic</span> <span word="field">field</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="become">become</span> <span word="magnetized">magnetized</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="magma">magma</span> <span word="become">become</span> <span word="magnetized">magnetized</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="cools">cools</span> <span word="and">and</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="in">in</span> <span word="the">the</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="series">series</span> <span word="of">of</span> <span word="magnetic">magnetic</span> <span word="stripes">stripes</span> <span word="running">running</span> <span word="parallel">parallel</span> <span word="to">to</span> <span word="the">the</span> <span word="axis">axis</span> <span word="of">of</span> <span word="the">the</span> <span word="rift">rift</span>. <span word="The">The</span> <span word="oceanic">oceanic</span> <span word="crust">crust</span> <span word="thus">thus</span> <span word="serves">serves</span> <span word="as">as</span> <span word="a">a</span> <span word="magnetic">magnetic</span> <span word="tape">tape</span> <span word="recording">recording</span> <span word="of">of</span> <span word="the">the</span> <span word="history">history</span> <span word="of">of</span> <span word="the">the</span> <span word="geomagnetic">geomagnetic</span> <span word="field">field</span> <span word="that">that</span> <span word="can">can</span> <span word="be">be</span> <span word="dated">dated</span> <span word="independently">independently</span>; <span word="the">the</span> <span word="width">width</span> <span word="of">of</span> <span word="the">the</span> <span word="stripes">stripes</span> <span word="indicates">indicates</span> <span word="the">the</span> <span word="rate">rate</span> <span word="of">of</span> <span word="the">the</span> <span word="sea">sea</span>-<span word="floor">floor</span> <span word="spreading">spreading</span>.</p>
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