美国自然人文地理(英文讲授)

GeographyoftheUSAGulfofMexicoTheAtlanticThePacificNationalFlagThe50starsrepresentthe50states,the13stripesrepresentthe13originalcolonies;knownasOldGlory.AmericanNationalEmblemArrowsmeaningself-protectionOlivebranches:thepursuitofpeaceGeologicalSurveyTheUnitedStatescanbedividedintothreepartsaccordingtoitsgeographicalfeatures:theeasternpart,thewesternpart,andthegreatcentralplaininbetween.TheeasternpartismadeupofthehighlandsformedbytheAppalachianRange.Itholdsonesixthofthenationalterritoryonthecontinent.Thesehighlandsarerelativelylow.Theaveragealtitudeisonly800metersabovesealeave.TherangebeginsfromnorthMaineandreachestocentralAlabama,coveringadistanceof1200miles.Threecomponentsmakeupthisuplandbelt,thePiedmontPlateauintheeast,theAppalachianPlateauinthewestandtheAppalachianRangeinthemiddle.ThewesternpartconsistsofhighplateausandmountainsformedbytheGreatCordilleraRange,extendingfromCanadathroughthewesternpartoftheUnitedStatestoMexicoandfurthersouth.FromwesttoeastthismountainsystemiscomposedoftheCoastRange,theCascadesandtheRockyMountains.Thewholeareaofthispartholdsonethirdofthecountry’sterritoryonthecontinent.RockyMountains/RockiesFromthepeacefulvillage,RockyMountainscanbeviewedinthedistance.MountainlionYellowstoneNationalPark,locatedinnorthwesternpartofWyomingTheoldestnationalparkintheworldandthelargestwildlifepreserveintheUSA.Yellowstonehasthousandsofhotspringsandmorethan200geysers,withOldFaithfulasthemostfamous.BetweentheRockyMountainsandtheAppalachiansliesthecentralplainwhichoccupiesonesecondofAmerica’slandmassonthecontinent.ItstretchesfromtheGreatLakesinthenorthtotheGulfofMexicointhesouth.DrainedbytheMississippianditstributariesGreatPlainsTheThreeMajorRiverSystemsThesystemoftheGulf,thesystemoftheAtlanticandthesystemofthePacific.(1)TheMississippiRiveristhelongestandthemostimportantriverinthesystemoftheGulf.ItflowsfromtheGreatLakestotheGulfofMexico,havingthelengthof6,262kilometersandadrainageareaof3,225,000squarekilometers.Itisofthegreatestriversintheworld.TheMississippihasmanytributaries,amongwhichtheMissouriandtheOhioaretwoofitslargestones.Theseriversformanimportantinlandnavigationandirrigationsystem.MississippiRiverDelta(2)TherearenolongriversinthesystemoftheAtlantic.TheHudsonRiver,linkedbycanalswiththefiveGreatLakes,flowsthroughthestateofNewYork,havingalengthofonly520kilometers.Itis,however,oneofthemainarteriesforinlandwaterwaytraffic.TheDelawareRiverformstheboundaryofPennsylvaniaandNewJersey.Washington,thecapitaloftheU.S.A.,isonthePotomacRiver.TheSt.LawrenceRiverformspartoftheboundarybetweenCanadaandtheU.S.A.,servingasaninternationalriver.BearMountainBridgespanstheHudsonRivernearPeekskill,NewYork.(3)InthesystemofthePacific,therearetwomajorrivers:theColumbiaRiverandtheColoradoRiver.Theyflowthroughthewesternplateausandarerichinpotentialwaterpowerresourcesduetotheirswiftcurrents.TheColumbiaRiverrisesinCanadaandflowsthroughWashingtonStateandformspartoftheboundarybetweenOregonandWashington.ItfinallyemptiesintothePacific.TheColoradoRiverflowsthoughColorado,Utah,ArizonaandformspartoftheboundarybetweenCaliforniaandArizonaandthenpoursintotheGulfofCalifornia.TheColoradoRiverhascarvedanumberofdeepcanyonsandgorgesalongitspaththroughtheAmericanstatesofColoradoandUtah.OneofthelongestriversofNorthAmerica,theColoradoRiverspans2330kmfromitssourceinnorthernColorado,intheUnitedStates,toitsterminusinMexicoattheGulfofCalifornia.LakeMead,avastartificiallake,straddlestheborderbetweenArizonaandNevada.ThelakewasformedbytheconstructionoftheHooverDamontheColoradoRiver.Duringwetperiods,itstoresexcesswateruntilitisneeded.GreatLakesThefiveGreatLakeslyingbetweentheboundaryofCanadaandtheUnitedStatesare:LakeMichigan,LakeSuperior,LakeErie,LakeHuronandLakeOntario.LakeMichiganiswhollywithintheUnitedStateswhiletheotherfourrunalongthenationalboundarybetweentheU.S.A.andCanada.ThefiveGreatLakesareopentonavigationbylargesteamers.LakeMichigan,innorthcentralUnitedStates,isthethirdlargestoftheGreatLakes,andtheonlyonelyingwhollywithintheUnitedStates,borderedbyMichiganonthenorthandeast,Indianaonthesouth,andIllinoisandWisconsinonthewest.Thelakeis494kmlongandupto190kmwide,withanareaof57,800sqkm.LakeSuperior,largestbodyoffreshwaterintheworld,thedeepestandwesternmostofthefiveGreatLakes,itis560kmlongandhasasurfaceareaofabout82,100sqkm;abouttwo-thirdsofthelakeisintheUnitedStates.LakeErie,southernmostandfourthlargestoftheGreatLakesofNorthAmerica,isborderedonthenorthbyOntario,Canada,ontheeastbyNewYork,onthesouthbyPennsylvaniaandOhio,andonthewestbyMichigan.LakeEriecovers25,700sqkm,almostevenlydividedbetweentheU.S.andCanada.LakeHuronisthesecondlargestofthefiveGreatLakesofcentralNorthAmerica.LocatedastridetheboundarybetweentheUnitedStatesandCanada,LakeHuronisborderedonthenorthandeastbyOntario,Canada,andonthewestbyMichigan.TheareaofLakeHuron,is59,600sqkmofwhich36,001sqkmareinCanada.LakeOntario,centralNorthAmerica,isborderedonthenorthbytheCanadianprovinceofOntarioandonthesouthbythestateofNewYork.Some311kmlonganduptoabout85kmwide,thelakecoversanareaof19,010sqkm,sligh