Thesefactsareofhighgeologicalinterestwithrespecttotheclimateofthenorthernhemisphereattheperiodwhenbouldersweretransported。
Iwillnotheredetailhowsimplythetheoryoficebergsbeingchargedwithfragmentsofrock，explaintheoriginandpositionofthegiganticbouldersofeasternTierradelFuego，onthehighplainofSantaCruz，andontheislandofChiloe。InTierradelFuego，thegreaternumberofboulderslieonthelinesofoldsea-channels，nowconvertedintodryvalleysbytheelevationoftheland。Theyareassociatedwithagreatunstratifiedformationofmudandsand，containingroundedandangularfragmentsofallsizes，whichhasoriginated[15]intherepeatedploughingupofthesea-bottombythestrandingoficebergs，andbythemattertransportedonthem。Fewgeologistsnowdoubtthatthoseerraticboulderswhichlienearloftymountainshavebeenpushedforwardbytheglaciersthemselves，andthatthosedistantfrommountains，andembeddedinsubaqueousdeposits，havebeenconveyedthithereitheronicebergsorfrozenincoast-ice。Theconnectionbetweenthetransportalofbouldersandthepresenceoficeinsomeform，isstrikinglyshownbytheirgeographicaldistributionovertheearth。InSouthAmericatheyarenotfoundfurtherthan48degs。oflatitude，measuredfromthesouthernpole；inNorthAmericaitappearsthatthelimitoftheirtransportalextendsto53。5degs。fromthenorthernpole；butinEuropetonotmorethan40degs。oflatitude，measuredfromthesamepoint。Ontheotherhand，intheintertropicalpartsofAmerica，Asia，andAfrica，theyhaveneverbeenobserved；norattheCapeofGoodHope，norinAustralia。[16]
OntheClimateandProductionsoftheAntarcticIslands——ConsideringtheranknessofthevegetationinTierradelFuego，andonthecoastnorthwardofit，theconditionoftheislandssouthandsouth-westofAmericaistrulysurprising。SandwichLand，inthelatitudeofthenorthpartofScotland，wasfoundbyCook，duringthehottestmonthoftheyear，“coveredmanyfathomsthickwitheverlastingsnow；“andthereseemstobescarcelyanyvegetation。Georgia，anisland96mileslongand10broad，inthelatitudeofYorkshire，“intheveryheightofsummer，isinamannerwhollycoveredwithfrozensnow。”Itcanboastonlyofmoss，sometuftsofgrass，andwildburnet；ithasonlyoneland-birdAnthuscorrendera，yetIceland，whichis10degs。nearerthepole，has，accordingtoMackenzie，fifteenland-birds。TheSouthShetlandIslands，inthesamelatitudeasthesouthernhalfofNorway，possessonlysomelichens，moss，andalittlegrass；andLieut。Kendall[17]foundthebay，inwhichhewasatanchor，beginningtofreezeataperiodcorrespondingwithour8thofSeptember。Thesoilhereconsistsoficeandvolcanicashesinterstratified；
andatalittledepthbeneaththesurfaceitmustremainperpetuallycongealed，forLieut。Kendallfoundthebodyofaforeignsailorwhichhadlongbeenburied，withthefleshandallthefeaturesperfectlypreserved。Itisasingularfact，thatonthetwogreatcontinentsinthenorthernhemispherebutnotinthebrokenlandofEuropebetweenthem，wehavethezoneofperpetuallyfrozenundersoilinalowlatitude——namely，in56degs。
inNorthAmericaatthedepthofthreefeet，[18]andin62degs。inSiberiaatthedepthoftwelvetofifteenfeet——astheresultofadirectlyoppositeconditionofthingstothoseofthesouthernhemisphere。Onthenortherncontinents，thewinterisrenderedexcessivelycoldbytheradiationfromalargeareaoflandintoaclearsky，norisitmoderatedbythewarmth-bringingcurrentsofthesea；theshortsummer，ontheotherhand，ishot。IntheSouthernOceanthewinterisnotsoexcessivelycold，butthesummerisfarlesshot，forthecloudedskyseldomallowsthesuntowarmtheocean，itselfabadabsorbentofheat：andhencethemeantemperatureoftheyear，whichregulatesthezoneofperpetuallycongealedunder-soil，islow。Itisevidentthatarankvegetation，whichdoesnotsomuchrequireheatasitdoesprotectionfromintensecold，wouldapproachmuchnearertothiszoneofperpetualcongelationundertheequableclimateofthesouthernhemisphere，thanundertheextremeclimateofthenortherncontinents。