2023年托福阅读TPO20(试题+答案+译文)第3篇-FossilPreservation整理.pdf

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2023年托福阅读TPO20(试题+答案+译文)第3

篇:FossilPreservation整理

TPO是我们常用的托福模考工具，对我们的备考很有价值，下面

我给大家带来托福阅读TPO20(试题+答案+译文)第3篇:Fossil

Preservation。

托福阅读原文

【1】Whenoneconsidersthemanywaysbywhichorganismsare

completelydestroyedafterdeath,itisremarkablethatfossilsareas

commonastheyare.Attackbyscavengersandbacteria,chemicaldecay,

anddestructionbyerosionandothergeologicagenciesmaketheodds

againstpreservationveryhigh.However,thechancesofescaping

completedestructionarevastlyimprovediftheorganismhappenstohave

amineralizedskeletonanddiesinaplacewhereitcanbequicklyburied

bysediment.Bothoftheseconditionsareoftenfoundontheoceanfloors,

whereshelledinvertebrates(organismswithoutspines)flourishandare

coveredbythecontinuousrainofsedimentaryparticles.Althoughmost

fossilsarefoundinmarinesedimentaryrocks,theyalsoarefoundin

terrestrialdepositsleftbystreamsandlakes.Onoccasion,animalsand

plantshavebeenpreservedafterbecomingimmersedintarorquicksand,

trappediniceorlavaflows,orengulfedbyrapidfallsofvolcanicash.

【2】Thetermfossiloftenimpliespetrifaction,literallya

transformationintostone.Afterthedeathofanorganism,thesofttissueis

ordinarilyconsumedbyscavengersandbacteria.Theemptyshellofa

snailorclammaybeleftbehind,andifitissufficientlydurableand

resistanttodissolution,itmayremainbasicallyunchangedforalong

periodoftime.Indeed,unalteredshellsofmarineinvertebratesareknown

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千里之行，始于足下。

fromdepositsover100millionyearsold.Inmanymarinecreatures,

however,theskeletoniscomposedofamineralvarietyofcalcium

carbonatecalledaragonite.Althougharagonitehasthesamecomposition

asthemorefamiliarmineralknownascalcite,ithasadifferentcrystal