Insignificantasthisstreamis，theJesuitFalconer，whoseinformationisgenerallysoverycorrect，figuresitasaconsiderableriver，risingatthefootoftheCordillera。Withrespecttoitssource，IdonotdoubtthatthisisthecasefortheGauchosassuredme，thatinthemiddleofthedrysummer，thisstream，atthesametimewiththeColoradohasperiodicalfloods；whichcanonlyoriginateinthesnowmeltingontheAndes。ItisextremelyimprobablethatastreamsosmallastheSaucethenwas，shouldtraversetheentirewidthofthecontinent；andindeed，ifitweretheresidueofalargeriver，itswaters，asinotherascertainedcases，wouldbesaline。DuringthewinterwemustlooktothespringsroundtheSierraVentanaasthesourceofitspureandlimpidstream。IsuspecttheplainsofPatagonialikethoseofAustralia，aretraversedbymanywater-courseswhichonlyperformtheirproperpartsatcertainperiods。ProbablythisisthecasewiththewaterwhichflowsintotheheadofPortDesire，andlikewisewiththeRioChupat，onthebanksofwhichmassesofhighlycellularscoriaewerefoundbytheofficersemployedinthesurvey。
Asitwasearlyintheafternoonwhenwearrived，wetookfreshhorses，andasoldierforaguide，andstartedfortheSierradelaVentana。ThismountainisvisiblefromtheanchorageatBahiaBlanca；andCapt。FitzRoycalculatesitsheighttobe3340feet——analtitudeveryremarkableonthiseasternsideofthecontinent。Iamnotawarethatanyforeigner，previoustomyvisit，hadascendedthismountain；andindeedveryfewofthesoldiersatBahiaBlancaknewanythingaboutit。Henceweheardofbedsofcoal，ofgoldandsilver，ofcaves，andofforests，allofwhichinflamedmycuriosity，onlytodisappointit。Thedistancefromthepostawasaboutsixleaguesoveralevelplainofthesamecharacterasbefore。
Theridewas，however，interesting，asthemountainbegantoshowitstrueform。Whenwereachedthefootofthemainridge，wehadmuchdifficultyinfindinganywater，andwethoughtweshouldhavebeenobligedtohavepassedthenightwithoutany。Atlastwediscoveredsomebylookingclosetothemountain，foratthedistanceevenofafewhundredyardsthestreamletswereburiedandentirelylostinthefriablecalcareousstoneandloosedetritus。IdonotthinkNatureevermadeamoresolitary，desolatepileofrock；——itwelldeservesitsnameof_Hurtado_，orseparated。Themountainissteep，extremelyrugged，andbroken，andsoentirelydestituteoftrees，andevenbushes，thatweactuallycouldnotmakeaskewertostretchoutourmeatoverthefireofthistle-stalks。[1]Thestrangeaspectofthismountainiscontrastedbythesea-likeplain，whichnotonlyabutsagainstitssteepsides，butlikewiseseparatestheparallelranges。Theuniformityofthecolouringgivesanextremequietnesstotheview，——thewhitishgreyofthequartzrock，andthelightbrownofthewitheredgrassoftheplain，beingunrelievedbyanybrightertint。Fromcustom，oneexpectstoseeintheneighbourhoodofaloftyandboldmountain，abrokencountrystrewedoverwithhugefragments。Herenatureshowsthatthelastmovementbeforethebedoftheseaischangedintodrylandmaysometimesbeoneoftranquillity。UnderthesecircumstancesIwascurioustoobservehowfarfromtheparentrockanypebblescouldbefound。OntheshoresofBahiaBlanca，andnearthesettlement，thereweresomeofquartz，whichcertainlymusthavecomefromthissource：thedistanceisforty-fivemiles。
Thedew，whichintheearlypartofthenightwettedthesaddle-clothsunderwhichweslept，wasinthemorningfrozen。Theplain，thoughappearinghorizontal，hadinsensiblyslopeduptoaheightofbetween800and900
feetabovethesea。Inthemorning9thofSeptembertheguidetoldmetoascendthenearestridge，whichhethoughtwouldleadmetothefourpeaksthatcrownthesummit。Theclimbingupsuchroughrockswasveryfatiguing；thesidesweresoindented，thatwhatwasgainedinonefiveminuteswasoftenlostinthenext。Atlast，whenIreachedtheridge，mydisappointmentwasextremeinfindingaprecipitousvalleyasdeepastheplain，whichcutthechaintransverselyintwo，andseparatedmefromthefourpoints。Thisvalleyisverynarrow，butflat-bottomed，anditformsafinehorse-passfortheIndians，asitconnectstheplainsonthenorthernandsouthernsidesoftherange。Havingdescended，andwhilecrossingit，Isawtwohorsesgrazing：Iimmediatelyhidmyselfinthelonggrass，andbegantoreconnoitre；butasIcouldseenosignsofIndiansIproceededcautiouslyonmysecondascent。Itwaslateintheday，andthispartofthemountain，liketheother，wassteepandrugged。Iwasonthetopofthesecondpeakbytwoo’clock，butgottherewithextremedifficulty；everytwentyyardsIhadthecrampintheupperpartofboththighs，sothatIwasafraidIshouldnothavebeenabletohavegotdownagain。Itwasalsonecessarytoreturnbyanotherroad，asitwasoutofthequestiontopassoverthesaddle-back。Iwasthereforeobligedtogiveupthetwohigherpeaks。Theiraltitudewasbutlittlegreater，andeverypurposeofgeologyhadbeenanswered；sothattheattemptwasnotworththehazardofanyfurtherexertion。Ipresumethecauseofthecrampwasthegreatchangeinthekindofmuscularaction，fromthatofhardridingtothatofstillharderclimbing。Itisalessonworth。remembering，asinsomecasesitmightcausemuchdifficulty。