从雅思阅读真题积累词汇SandDune

很多雅思考生在阅读了雅思真题后，或许更了解了出题思路和解题方法，但不知大家有没有做过有心人，发掘雅思阅读真题的其它功能呢？其实，通过雅思阅读真题也可以有的放矢地扩充雅思词汇量。今天，环球雅思向大家推荐一篇地理类科普性的雅思阅读真题文章SandDuner。阅读本文后，大家在丰富知识面之余，雅思词汇量也在不知觉中上涨哦。雅思阅读真题SandDuneTheaccumulationofwindblownsandmarksthebeginningofoneofnature'smostinterestingandbeautifulphenomena.Sanddunesoccurthroughouttheworld,fromcoastalandlakeshoreplainstoariddesertregions.Inadditiontotheremarkablestructureandpatternsofsanddunes,theyalsoprovidehabitatsforavarietyoflifewhichismarvelouslyadaptedtothisuniqueenvironment.Picturesquedunesagainstaskyofblueorafullmoon,withperfectlycontouredshadowsofripplesandundulatingcrests,havealwaysbeenafavoritesubjectofphotographers.Duneshavealsobeenthesubjectofmanydesertmovies,andhavehistoricallybeenaformidablebarriertovehicularandrailtravel.Dependinguponone'sparticularsituation,theycanbeoneofthemostincrediblybeautiful,thrilling,eerie,treacherousorjustplaininhospitableplacesonearth.Theoriginofsanddunesisverycomplex,buttherearethreeessentialprerequisites:(1)Anabundantsupplyofloosesandinaregiongenerallydevoidofvegetation(suchasanancientlakebedorriverdelta);(2)awindenergysourcesufficienttomovethesandgrains;(3)atopographywherebythesandparticleslosetheirmomentumandsettleout.Anynumberofobjects,suchasshrubs,rocksorfencepostscanobstructthewindforcecausingsandtopileupindriftsandultimatelylargedunes.Thereareevenreportsofanthillsformingthenucleusuponwhichsanddunesarebuilt.Thedirectionandvelocityofwinds,inadditiontothelocalsupplyofsand,resultinavarietyofduneshapesandsizes.Thewindmovesindividualgrainsalongtheinclinedwindwardsurfaceuntiltheyreachthecrestandcascadedownthesteepleewardsideorslipface,pilingupatthebaseandslowlyencroachingonnewterritory.SomeCaliforniaduneswithcrestsonly30feethighmayadvance50feetayear,posingaseriousthreattonearbyfarmsandroads.Ifthewinddirectionisfairlyuniformovertheyears,thedunesgraduallyshiftinthedirectionoftheprevailingwind.Vegetationmaystabilizeadune,thuspreventingitsmovementwiththeprevailingwind.AlongtheOregoncoast,entireforestsmaycoversandduneareas.Sometimesseverestormsorotherdisturbancescandestroytheforestcanopyallowingsandfromnearbydunestomoveintothedisturbedarea.Infact,Mr.Wolffiahasstoodatthecrestofashiftingdunewherethetipofasitkaspruce(Piceasitchensis)wasprotrudingfromthesand.Thestructureandmineralcompositionofsandgrainsdependsonthegeologyofthemountainsthathavebeenerodedawaybywindandwater.Althoughmostdunesarecomposedofquartzandfeldspargrains,thebrilliantsnow-whitedunesofWhiteSands,NewMexicoarecomposedofgypsum.SpectacularblacksandbeachesofthetropicalSouthPacificislandsaremadeoffinevolcanicparticles.Gleamingwhitesandsoftropicalcoralbeachesandatollsarecomposedofaglistening,microscopicassortmentofreefanimalsandalgae,includingwave-wornfragmentsofbrightly-coloredcorals,minuteone-celledforaminiferans,fragmentsofseashells,star-shapedspongespiculesandfragmentsofjointedplatesfromacommoncalcareousgreenalga(Halimeda)thatgrowsamongsubmarineseagrassmeadowsandcoralreefs.Evidenceofabrasiononsandblastedsurfacesoftelephonepolesandpostsrevealsthatsandgrainsseldomtravelmorethanafewfeetabovetheground.Myriadsofsandgrainsbouncingandrollingupthewindwardsurfaceofaduneoftenformaseriesofridgesandtroughscalledwindripples.Bouncingsandgrainstendtolandonthewindwardsideofeachripple,thusproducingalowridge.Withoutgettingtoocomplicated,thespacingofripplesisrelatedtotheaveragedistancegrainsjump.Thisinturn,isrelatedtothewindvelocityandsizeofthegrains.Windripplesareoftenveryspectacularandphotogenic,especiallywhenthethousandsoftinyridgescatchtheshadowsofearlymorningorlateafternoon.Forcenturies,explorersandnaturaliststhroughouttheworldhavedescribedstrangesoundsemanatingfromsanddunes.Strangesqueakingsoundsarealsoproducedbybeachsandbysimplycompressingthesandwithyourfootorpokingitwitharod.SomeoftheearliestreferencesaboutacousticaldunesarefoundinChineseandMideasternchroniclesdatingbackmorethan1500years.MarcoPolodescribedweirdsoundsonajourneythroughtheGobiDesert,andCharlesDarwinmentioneditwhiletravelingthroughChile.Thesoundshavebeenvariouslydescribedassinging,whistling,squeaking,roaringandbooming.Someaccountscomparethesoundswithdistantkettledrums,artilleryfire,thunder,low-flyingpropelleraircraft,bassviolins,pipeorgansandhummingtelegraphwires.Lowfrequencysoundsareproducedwhencloselypackedsandgrainsslideovereachother,suchasanavalanchedowntheslipfaceofadune.Thestationarysandunderneathapparentlyactsasagiantsoundingboardoramplifiertoproducetheenormousvolumeofsound.Thesandmustbeverydryforsoundproduction,andunderamicroscopethegrainsappearmoreroundedandfinelypolishedcomparedwithordinary(silent)sand.AstronomersandgeologistshavespeculatedthatthisremarkablephenomenonmaybecommoninthewindyandnearlywaterlesssanddunesonMars.雅思阅读真题词汇积累：Dune沙丘Arid干旱的Picturesque风景如画的，独特的Formidable强大的Eerie可怕的，奇异的Treacherous背叛的Inhospitable冷淡的Prerequisite先决条件Devoid缺乏的Topography地形学Drift漂流Velocity速度Crest顶部，顶峰Stabilize使稳定Cascade成瀑布落下sandgrains沙粒foraminiferan有孔虫目abrasion磨损ripple波纹emanate散发该雅思阅读真题取自1月30日阅读考试第3篇题源文章。这篇环球雅思介绍的具有地理知识的雅思阅读真题SandDuner是否让你的词汇量轻轻松松的积累起来