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1、①Helloeveryone,todayIwanttoshowyouapartofhowtheearthwasmade,andmainlytalkaboutYellowstone.②Ascontinentsshiftandclash,volcanoeserupt,andglaciersgrowandrecede,theEarth’scrustiscarvedincountlessfascinatingways,leavingatrailofgeologicalmysteriesbehind.AndoneofthegreatestisYellowstoneNationa

2、lParkinWyoming.Thisisoneoftheworld’smostgeologicallyactiveplaces,shakenbyupto5000earthquakeseveryyear,andwithmoregeysersandhotspringsthanintherestoftheworldcombined.ScientistsstudyingYellowstoneareuncoveringaviolentpast.Carvedwater,crushedbyancientglaciersandblastedbythebiggestvolcanice

3、ruptionseverknownontheplanet.Andeventoday,YellowstoneisoneofthemostdangerousplacesonEarth.③YellowstoneisoneofthemostamazingplacesonEarth,andit’sunique.ItcontainssomeofAmerica’smoststunningsceneryandwildlife.Yellowstone is the world’s first national park which is in the northwestern corn

4、er of Wyoming and overlaps into Montana and Idaho.Theparkcovers3468squaremiles,63milesnorthtosouthand54mileseasttowest.It’saveryunusualgeologythatcreatedthepark.④OldFaithfulisthestarattractionofYellowstone.It’soneofthemostpredictablegeographicalfeaturesonEarth,eruptingalmost91minutes.⑤B

5、eneathOldFaithfulisarathercomplexplumbingsystem,filledwithcavernsandconduitsandconstrictions.Rainwatersaturatingthegroundaroundthegeyserslowlyfillsitsundergroundreservoir.Hotrocksbelowgroundheatthewaterunderpressureforaround90minutes.Suddenlysomewaterspurtsthroughatiny,fiveinchwidecrack

6、intherocks.Thiscausesadropinthepressurewithinthewaterchamber.Inainstant,thousandsofgallonsofwaterareturnedtosteamandblastedupintotheair.Thegasescomeoutfromthegeysersisthesamemixthatisfoundcomingoutofvolcanoes.Sogasesareclearevidencethatunderthespringsandgeysersisavolcano.Yellowstonemust

7、bepoweredbytheheatofthevolcano.⑥Peoplecan’tseeasmokingvolcanoorabigsteepvolcaniccrater.Butwhereisthevolcano?ScientistsfindoutevidencestoshowusthatYellowstoneisthesupervolcano.⑦Theblacklayerthatgeologistscall“obsidian”isactuallyatypeofglass.It’scrucialevidencethattherocksandsoil