Abigbouldersticksoutofthedriedmud.Thisrockistooheavytopickup.Yet,ithasmysteriouslymoved.Atrailshowswhereitmovedacrossthe dirt.
Thisisn’ttheonlyrockonthemovehere.ManyoftherocksinthispartofDeathValleyinNorthAmericadon’tstayinoneplace.Theirtrailscrisscrossthecrackedmudofadried lake.
Somerocksmoveinstraightlines.Somemoveinpairs.Otherszigzagthiswayandthat,leavingajaggedtrail.Howdidtheymove?Noonehaseverseenit.It’sa mystery.
Bouldersmysteriouslyzigand zaginDeathValley,California, U.S.A.
North
America
Death
Valley
Amantakesaphotographofbouldersandtheir trails.
Searching
foraCause
Overtheyears,peoplehavewonderedwhatmakestherocksmove.Theyhavecomeupwithsomewildideas.Somepeoplethinktherocksaremagical.Otherssaypranksterssecretlymovethe rocks.
Scientistswantedabettertheory.So,theylookedforsome evidence.
LookingtoNature
Anearlytheorywasthatgravitymovestherocks.Gravityisaforceinnature.Itpullsthingsdown.Manyrocksmoveduphill,notdownhill.So,gravitywasn’tthe answer.
Anothertheorywasthatstrongwindspushedtherocks.Scientiststestedthistheory.Thetestsshowedthateventhestrongestwindsintheareaweren’tstrongenough.Theycouldn’tmovebig boulders.
Thisvideofollowsthetrailmadebyaheavy stone.
ColdClue
Thenscientistsrealizedanimportantfact.Therocksmoveonlyinwinter,whenthisareafloods.Onescientistdecidedtostudythe water.
Shefoundaslimybacteriagrewinthewater.Theslimemadethegroundslippery.Onawindyday,asmallwindcouldmaketherocks slide.
AnExperiment
Thewatergaveanotherscientistadifferentidea.Heknewthaticefloats.Maybeicehelpedtherocks move.
Totesthistheory,hefrozearockinatrayofwaterandsand.Theiceliftedtherockalittlebit.Whenheblewontherock,itmoved!Itleftatrailinthe sand.
Thebacteriaandicetheoriesmightbetrue.Yetnoonehasseentherocksmove.Thismysteryremains unsolved.
Scientist RalphLorenz standsnearafloodedareaofDeath Valley.