TheseplainsarethenewestpartofAmerica，formanyofthemhaveemergedfromtheseaonlyinrecentgeologicaltimes。Takenasawholetheresemblancebetweenthetwocontinentsisstriking。
IfthesefourphysiographicprovincesofNorthandSouthAmericalayinsimilarlatitudesintherespectivecontinentswemightexpecteachpairtohaveacloselysimilareffectonlife。Infauna，flora，andeveninhumanhistorytheywouldpresentbroadandimportantresemblances。Asamatteroffact，however，theyareasdifferentascanwellbeimagined。WhereNorthAmerica，isbathedbyicywatersfullofsealsandfloatingiceSouthAmericaisbathedbywarmseasfullofflying-fishandcoralreefs。Thenortherncontinentisbroadestinthecoollatitudesthataremostfavorableforhumanactivity。Thesouthernexpandsmostwidelyinlatitudeswhosedebilitatingmonotonyofheatandmoistureistheworstofhandicapstohumanprogress。Thegreatriversofthenortherncontinentcorrespondverycloselytothoseofthesouthern。TheMackenzie，however，isboundintherigidbandsofwinterforeightmonthseachyear，whiletheOrinoco，thecorrespondingSouthAmericanriver，liesswelteringunderatropicalsunwhichburnsitsgrassyplainstobitterdustevenasthesharpcoldreducedtheMackenzieregiontobarrentundra。TheSt。Lawrenceflowsthroughfertilegrainfieldsandthehomesofanactivepeopleofthetemperatezone，buttheAmazonwindsitsslowwayamidthemalariouslanguorofvasttropicalforestsinwhichthetreesshutouttheskyandthefewnativesareapatheticwiththeeternalinertiaofthehot，damptropics。
OnlywhenwecometotheMississippiinthenortherncontinentandtheRiodelaPlatainthesoutherndowefindapairofriverswhichcorrespondtoanydegreeinthecharacterofthelifesurroundingthem，aswellasintheirphysiographiccharacter。Yetevenherethereisavastdifference，especiallyintheuppercoursesoftheriver。Eachatitsmouthflowsthrougharich，fertileplainoccupiedbyaprogressive，prosperouspeople。ButtheRiodelaPlatatakesitsriseinoneoftheworld’smostbackwardplains，thehomeofuncivilizedIndians，heartlessrubberadventurers，andthemostrapaciousofofficials。Notinfrequently，thedegeneratewhitemenoftheseregions，yieldingtothesubtleandinsidiousinfluenceofthetropics，inflictthemostoutrageousabusesuponthenatives，andevenkillthemonslightprovocation。Thenativesinturnhatetheiroppressors，andwhenthechancecomesbetraythemorleavethemtoperishinsicknessandmisery。TheupperMississippi，ontheotherhand，comesfromaplainwhereagricultureiscarriedonwithmorelabor-savingdevicesthanarefoundanywhereelseintheworld。ThereStateslikeWisconsinandMinnesotastandintheforefrontofeducationalandsocialprogress。ThecontrastsbetweenthecorrespondingriversofthetwoAmericasaretypicalofthecontrastsinthehistoryofthetwocontinents。
CHAPTERIII。THEGEOGRAPHICPROVINCESOFNORTHAMERICA
ThefourgreatphysicaldivisionsofNorthAmerica——theLaurentianhighland，theAppalachianhighland，theplains，andthewesterncordillera——arestrikinglydifferentinformandstructure。TheLaurentianhighlandpresentsamonotonouswasteofroughhills，irregularvalleys，picturesquelakes，andcrookedrivers。Mostofitisthinlyclothedwithpinetreesandbushessuchastheblueberryandhuckleberry。Yeteverywheretheancientrockcropsout。Noonecantraveltherewithoutbecomingtiresomelyfamiliarwithfine-grained，shatteredschists，coarsegranites，andtheircuriouslybandedrelatives，thegneisses。