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1、①Helloeveryone,todayIwanttoshowyouapartofhowtheearthwasmade,andmainlytalkaboutYellowstone.②Ascontinentsshiftandclash,volcanoeserupt,andglaciersgrowandrecede,theEarth’scrustiscarvedincountlessfascinatingways,leavingatrailofgeologicalmysteriesbehind.Andoneoftheg
2、reatestisYellowstoneNationalParkinWyoming.Thisisoneoftheworld’smostgeologicallyactiveplaces,shakenbyupto5000earthquakeseveryyear,andwithmoregeysersandhotspringsthanintherestoftheworldcombined.ScientistsstudyingYellowstoneareuncoveringaviolentpast.Carvedwater,c
3、rushedbyancientglaciersandblastedbythebiggestvolcaniceruptionseverknownontheplanet.Andeventoday,YellowstoneisoneofthemostdangerousplacesonEarth.③YellowstoneisoneofthemostamazingplacesonEarth,andit’sunique.ItcontainssomeofAmerica’smoststunningsceneryandwildlife
4、.Yellowstone is the world’s first national park which is in the northwestern corner of Wyoming and overlaps into Montana and Idaho.Theparkcovers3468squaremiles,63milesnorthtosouthand54mileseasttowest.It’saveryunusualgeologythatcreatedthepark.④OldFaithfulisthes
5、tarattractionofYellowstone.It’soneofthemostpredictablegeographicalfeaturesonEarth,eruptingalmost91minutes.⑤BeneathOldFaithfulisarathercomplexplumbingsystem,filledwithcavernsandconduitsandconstrictions.Rainwatersaturatingthegroundaroundthegeyserslowlyfillsitsun
6、dergroundreservoir.Hotrocksbelowgroundheatthewaterunderpressureforaround90minutes.Suddenlysomewaterspurtsthroughatiny,fiveinchwidecrackintherocks.Thiscausesadropinthepressurewithinthewaterchamber.Inainstant,thousandsofgallonsofwaterareturnedtosteamandblastedup
7、intotheair.Thegasescomeoutfromthegeysersisthesamemixthatisfoundcomingoutofvolcanoes.Sogasesareclearevidencethatunderthespringsandgeysersisavolcano.Yellowstonemustbepoweredbytheheatofthevolcano.⑥Peoplecan’tseeasmokingvolcanoorabigsteepvolcaniccrater.Butwhereist
8、hevolcano?ScientistsfindoutevidencestoshowusthatYellowstoneisthesupervolcano.⑦Theblacklayerthatgeologistscall“obsidian”isactuallyatypeofglass.It’scrucialevidencethattherocksandsoil
