JackDykinga/GettyImagesTheChangingSurfaceofEarthFlyGeyser,Nevadaisahuman-madedrillwell,whichisnowaconstantlyspoutinghotspring.ItislocatedintheBlackRockDesert,nearGerlach,Nevada.Thetufaterraces,or“naturalsteps,”areformedbymineraldepositsfromthesprings.Sendallinquiriesto:Glencoe/McGraw-Hill8787OrionPlaceColumbus,OH43240-4027ISBN:0-07-861752-9PrintedintheUnitedStatesofAmerica.2345678910027/043090807060504Copyright©2005byTheMcGraw-HillCompanies,Inc.Allrightsreserved.ExceptaspermittedundertheUnitedStatesCopyrightAct,nopartofthispublicationmaybereproducedordistributedinanyformorbyanymeans,orstoredinadatabaseorretrievalsystem,withoutpriorwrittenpermissionofthepublisher.TheNationalGeographicfeaturesweredesignedanddevelopedbytheNationalGeographicSociety’sEducationDivision.Copyright©NationalGeographicSociety.Thename“NationalGeographicSociety”andtheYellowBorderRectanglearetrademarksoftheSociety,andtheiruse,withoutpriorwrittenpermission,isstrictlyprohibited.The“ScienceandSociety”andthe“ScienceandHistory”featuresthatappearinthisbookweredesignedanddevelopedbyTIMESchoolPublishing,adivisionofTIMEMagazine.TIMEandtheredborderaretrademarksofTimeInc.Allrightsreserved.JackDykinga/GettyImagesCONTENTWilliamC.Keel,PhDDepartmentofPhysicsandAstronomyUniversityofAlabamaTuscaloosa,ALRobertNiersteScienceDepartmentHeadHendrickMiddleSchool,PlanoISDPlano,TXMATHMichaelHopper,DEngManagerofAircraftCertificationL-3CommunicationsGreenville,TXTeriWillard,EdDMathematicsCurriculumWriterBelgrade,MTREADINGCarolA.Senf,PhDSchoolofLiterature,Communication,andCultureGeorgiaInstituteofTechnologyAtlanta,GASAFETYAileenDuc,PhDScience8TeacherHendrickMiddleSchool,PlanoISDPlano,TXSandraWest,PhDDepartmentofBiologyTexasStateUniversity-SanMarcosSanMarcos,TXACTIVITYTESTERSNermaCoatsHendersonPickeringtonLakeviewJr.HighSchoolPickerington,OHMaryHelenMariscal-CholkaWilliamD.SliderMiddleSchoolElPaso,TXScienceKitandBorealLaboratoriesTonawanda,NYG◆iiiAuthorsSeriesConsultantsLoisBurdetteGreenBankElementary-MiddleSc...
