35第35章 (2/2)

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landforms.Betweenthewesternmountainrangeslievastplateausandbasins,amongwhichtheGreatBasinandtheMojaveDesertarerepresentativearidandsemi-aridregionswithsparserainfallandsparsevegetation.
  

  

  
ThecentralpartoftheUnitedStatesisoccupiedbytheworld-famousCentralPlains,alsoknownastheGreatPlains.StretchingfromthenorthernborderofCanadaallthewaytothesouthernGulfofMexicocoast,thisplainisflat,open,andextremelyfertile,knownasthe“granaryofNorthAmerica”.ItisthecoreagriculturalproductionareaoftheUnitedStates,plantinglargequantitiesofcorn,wheat,soybeans,andcotton,supportingthecountry’sstatusastheworld’slargestagriculturalexporter.
  

  

  
Theeasternregioniscomposedoftherelativelylow-lyingAppalachianMountainsandthenarrowAtlanticcoastalplain.TheAppalachianMountains,formedinancientgeologicalperiods,havegentleterrainandabundantforestresources.Theeasterncoastalplainisdenselypopulated,withdevelopedurbanagglomerations,prosperousports,andconvenienttransportation,becomingtheearliestdevelopedandmosteconomicallyprosperousregionintheUnitedStates.
  

  

  
Correspondingtoitscomplexterrain,theUnitedStateshasdiverseclimatetypes.Thenortheasternandnortherncentralregionsbelongtoatemperatecontinentalclimatewithdistinctfourseasons,coldandsnowywinters,andwarmandhumidsummers.Thesoutheasterncoastalareashaveasubtropicalhumidclimatewithabundantrainfall,hightemperatureandhumidityinsummer,andmildwinters.ThewesternPacificcoastpresentsazonalclimatedistribution:thenorthernPacificcoasthasatemperatemarineclimatewithperennialmildnessandabundantrainfall;theCaliforniaareainthewesthasaMediterraneanclimatewithdrysummersandrainywinters.Theinlandwesternplateausandbasinsbelongtoatemperatearidandsemi-aridclimatewithscarceprecipitationandlargetemperaturedifferencesbetweendayandnight.Alaskahasapolarandsubpolarcoldclimate,whileHawaiifeaturesatropicalmarineclimatewithperennialhightemperatureandpleasantscenery.
  

  

  
1.3RiverSystemsandNaturalResources
  

  

  
TheUnitedStateshascompletewatersystems,amongwhichtheMississippiRiversystemisthemostimportant.Knownasthe“FatherofWaters”inNorthAmerica,theMississippiRiveranditsnumeroustributariesformthelargestinlandriverbasininNorthAmerica,coveringnearlytwo-thirdsofthecontiguousUnitedStates.Theriversystemprovidesabundantirrigationwater,inlandshippingchannels,andhydropowerresourcesforthecentralplains,greatlypromotingthedevelopmentofagriculturalirrigation,inlandtransportation,andindustrialeconomyinthecentralUnitedStates.Inthenortheast,thefiveGreatLakesSuperior,Michigan,Huron,Erie,Ontarioconstitutethelargestfreshwaterlakegroupintheworld,withhugewaterstoragecapacity,shippingvalue,andecologicalvalue,nurturingtheurbanindustrialbeltinthenortheasternUnitedStates.
  

  

  
TheUnitedStatesisextremelyrichinnaturalresources,rankingamongthetopintheworldintermsofreservesandtypesofmineralresources,forestresources,energyresources,andbiologicalresources.Itsprovencrudeoilreserves,naturalgasreserves,coalreserves,ironore,copperore,andraremetalresourcesareallamongtheworld’sleadinglevels.Thecountry’sforestcoverageratereachesapproximately33%,withvastvirginforestsandforestcarbonsinks,providingsufficientrawmaterialsfortheforestryandpaperindustries.Atthesametime,theUnitedStateshasdiversebiologicalspeciesandcompleteecologicaltypes,withnumerousnationalparks,naturereserves,andwetlandprotectionareas,possessinghighecologicalprotectionvalueandtourismvalue.
  

  

  
Intermsofenergyresources,theUnitedStateshasachievedenergyind