Beforesuckingtheyarequitethin，butafterwardstheybecomeroundandbloatedwithblood，andinthisstateareeasilycrushed。OnewhichIcaughtatIquique，fortheyarefoundinChileandPeru，wasveryempty。Whenplacedonatable，andthoughsurroundedbypeople，ifafingerwaspresented，theboldinsectwouldimmediatelyprotrudeitssucker，makeacharge，andifallowed，drawblood。Nopainwascausedbythewound。Itwascurioustowatchitsbodyduringtheactofsucking，asinlessthantenminutesitchangedfrombeingasflatasawafertoaglobularform。Thisonefeast，forwhichthebenchucawasindebtedtooneoftheofficers，keptitfatduringfourwholemonths；but，afterthefirstfortnight，itwasquitereadytohaveanothersuck。
　　March27th——WerodeontoMendoza。Thecountrywasbeautifullycultivated，andresembledChile。Thisneighbourhoodiscelebratedforitsfruit；andcertainlynothingcouldappearmoreflourishingthanthevineyardsandtheorchardsoffigs，peaches，andolives。Weboughtwater-melonsnearlytwiceaslargeasaman’shead，mostdeliciouslycoolandwell-flavoured，forahalfpennyapiece；andforthevalueofthreepence，halfawheelbarrowfulofpeaches。Thecultivatedandenclosedpartofthisprovinceisverysmall；
　　thereislittlemorethanthatwhichwepassedthroughbetweenLuxanandthecapital。Theland，asinChile，owesitsfertilityentirelytoartificialirrigation；anditisreallywonderfultoobservehowextraordinarilyproductiveabarrentraversiaisthusrendered。
　　WestayedtheensuingdayinMendoza。Theprosperityoftheplacehasmuchdeclinedoflateyears。Theinhabitantssay“itisgoodtolivein，butverybadtogrowrichin。”Thelowerordershavethelounging，recklessmannersoftheGauchosofthePampas；andtheirdress，riding-gear，andhabitsoflife，arenearlythesame。Tomymindthetownhadastupid，forlornaspect。Neithertheboastedalameda，northescenery，isatallcomparablewiththatofSantiago；buttothosewho，comingfromBuenosAyres，havejustcrossedtheunvariedPampas，thegardensandorchardsmustappeardelightful。SirF。Head，speakingoftheinhabitants，says，“Theyeattheirdinners，anditissoveryhot，theygotosleep——andcouldtheydobetter？”IquiteagreewithSirF。Head：thehappydoomoftheMendozinosistoeat，sleepandbeidle。
　　March29th——WesetoutonourreturntoChile，bytheUspallatapasssituatednorthofMendoza。Wehadtocrossalongandmoststeriletraversiaoffifteenleagues。Thesoilinpartswasabsolutelybare，inotherscoveredbynumberlessdwarfcacti，armedwithformidablespines，andcalledbytheinhabitants“littlelions。”Therewere，also，afewlowbushes。Althoughtheplainisnearlythreethousandfeetabovethesea，thesunwasverypowerful；andtheheataswellasthecloudsofimpalpabledust，renderedthetravellingextremelyirksome。OurcourseduringthedaylaynearlyparalleltotheCordillera，butgraduallyapproachingthem。Beforesunsetweenteredoneofthewidevalleys，orratherbays，whichopenontheplain：
　　thissoonnarrowedintoaravine，wherealittlehigherupthehouseofVillaVicencioissituated。Aswehadriddenalldaywithoutadropofwater，bothourmulesandselveswereverythirsty，andwelookedoutanxiouslyforthestreamwhichflowsdownthisvalley。Itwascurioustoobservehowgraduallythewatermadeitsappearance：ontheplainthecoursewasquitedry；bydegreesitbecamealittledamper；thenpuddlesofwaterappeared；thesesoonbecameconnected；andatVillaVicenciotherewasanicelittlerivulet。
　　30th——ThesolitaryhovelwhichbearstheimposingnameofVillaVicencio，hasbeenmentionedbyeverytravellerwhohascrossedtheAndes。Istayedhereandatsomeneighbouringminesduringthetwosucceedingdays。Thegeologyofthesurroundingcountryisverycurious。TheUspallatarangeisseparatedfromthemainCordillerabyalongnarrowplainorbasin，likethosesooftenmentionedinChile，buthigher，beingsixthousandfeetabovethesea。ThisrangehasnearlythesamegeographicalpositionwithrespecttotheCordillera，whichthegiganticPortillolinehas，butitisofatotallydifferentorigin：itconsistsofvariouskindsofsubmarinelava，alternatingwithvolcanicsandstonesandotherremarkablesedimentarydeposits；thewholehavingaverycloseresemblancetosomeofthetertiarybedsontheshoresofthePacific。FromthisresemblanceIexpectedtofindsilicifiedwood，whichisgenerallycharacteristicofthoseformations。
　　Iwasgratifiedinaveryextraordinarymanner。Inthecentralpartoftherange，atanelevationofaboutseventhousandfeet，Iobservedonabareslopesomesnow-whiteprojectingcolumns。Thesewerepetrifiedtrees，elevenbeingsilicified，andfromthirtytofortyconvertedintocoarsely-crystallizedwhitecalcareousspar。Theywereabruptlybrokenoff，theuprightstumpsprojectingafewfeetabovetheground。Thetrunksmeasuredfromthreetofivefeeteachincircumference。Theystoodalittlewayapartfromeachother，butthewholeformedonegroup。Mr。RobertBrownhasbeenkindenoughtoexaminethewood：hesaysitbelongstothefirtribe，partakingofthecharacteroftheAraucarianfamily，butwithsomecuriouspointsofaffinitywiththeyew。Thevolcanicsandstoneinwhichthetreeswereembedded，andfromthelowerpartofwhichtheymusthavesprung，hadaccumulatedinsuccessivethinlayersaroundtheirtrunks；andthestoneyetretainedtheimpressionofthebark。
　　Itrequiredlittlegeologicalpracticetointerpretthemarvellousstorywhichthissceneatonceunfolded；thoughIconfessIwasatfirstsomuchastonishedthatIcouldscarcelybelievetheplainestevidence。IsawthespotwhereaclusteroffinetreesoncewavedtheirbranchesontheshoresoftheAtlantic，whenthatoceannowdrivenback700milescametothefootoftheAndes。Isawthattheyhadsprungfromavolcanicsoilwhichhadbeenraisedabovethelevelofthesea，andthatsubsequentlythisdryland，withitsuprighttrees，hadbeenletdownintothedepthsoftheocean。Inthesedepths，theformerlydrylandwascoveredbysedimentarybeds，andtheseagainbyenormousstreamsofsubmarinelava——onesuchmassattainingthethicknessofathousandfeet；andthesedelugesofmoltenstoneandaqueousdepositsfivetimesalternatelyhadbeenspreadout。
　　Theoceanwhichreceivedsuchthickmasses，musthavebeenprofoundlydeep；
　　butagainthesubterraneanforcesexertedthemselves，andInowbeheldthebedofthatocean，formingachainofmountainsmorethanseventhousandfeetinheight。Norhadthoseantagonisticforcesbeendormant，whicharealwaysatworkwearingdownthesurfaceoftheland；thegreatpilesofstratahadbeenintersectedbymanywidevalleys，andthetreesnowchangedintosilex，wereexposedprojectingfromthevolcanicsoil，nowchangedintorock，whenceformerly，inagreenandbuddingstate，theyhadraisedtheirloftyheads。Now，allisutterlyirreclaimableanddesert；eventhelichencannotadheretothestonycastsofformertrees。Vast，andscarcelycomprehensibleassuchchangesmusteverappear，yettheyhavealloccurredwithinaperiod，recentwhencomparedwiththehistoryoftheCordillera；
　　andtheCordilleraitselfisabsolutelymodernascomparedwithmanyofthefossiliferousstrataofEuropeandAmerica。
　　April1st——WecrossedtheUpsallatarange，andatnightsleptatthecustom-house——theonlyinhabitedspotontheplain。Shortlybeforeleavingthemountains，therewasaveryextraordinaryview；red，purple，green，andquitewhitesedimentaryrocks，alternatingwithblacklavas，werebrokenupandthrownintoallkindsofdisorderbymassesofporphyryofeveryshadeofcolour，fromdarkbrowntothebrightestlilac。ItwasthefirstviewIeversaw，whichreallyresembledthoseprettysectionswhichgeologistsmakeoftheinsideoftheearth。
　　Thenextdaywecrossedtheplain，andfollowedthecourseofthesamegreatmountainstreamwhichflowsbyLuxan。Hereitwasafurioustorrent，quiteimpassable，andappearedlargerthaninthelowcountry，aswasthecasewiththerivuletofVillaVicencio。Ontheeveningofthesucceedingday，wereachedtheRiodelasVacas，whichisconsideredtheworststreamintheCordilleratocross。Asalltheserivershavearapidandshortcourse，andareformedbythemeltingofthesnow，thehourofthedaymakesaconsiderabledifferenceintheirvolume。Intheeveningthestreamismuddyandfull，butaboutdaybreakitbecomesclearer，andmuchlessimpetuous。ThiswefoundtobethecasewiththeRioVacas，andinthemorningwecrosseditwithlittledifficulty。
　　Thescenerythusfarwasveryuninteresting，comparedwiththatofthePortillopass。Littlecanbeseenbeyondthebarewallsoftheonegrandflat-bottomedvalley，whichtheroadfollowsuptothehighestcrest。Thevalleyandthehugerockymountainsareextremelybarren：duringthetwopreviousnightsthepoormuleshadabsolutelynothingtoeat，forexceptingafewlowresinousbushes，scarcelyaplantcanbeseen。InthecourseofthisdaywecrossedsomeoftheworstpassesintheCordillera，buttheirdangerhasbeenmuchexaggerated。IwastoldthatifIattemptedtopassonfoot，myheadwouldturngiddy，andthattherewasnoroomtodismount；butIdidnotseeaplacewhereanyonemightnothavewalkedoverbackwards，orgotoffhismuleoneitherside。Oneofthebadpasses，called_lasAnimas_thesouls，Ihadcrossed，anddidnotfindouttilladayafterwards，thatitwasoneoftheawfuldangers。Nodoubttherearemanypartsinwhich，ifthemuleshouldstumble，theriderwouldbehurleddownagreatprecipice；butofthisthereislittlechance。Idaresay，inthespring，the“laderas。”orroads，whicheachyearareformedanewacrossthepilesoffallendetritus，areverybad；butfromwhatI
　　saw，Isuspecttherealdangerisnothing。Withcargo-mulesthecaseisratherdifferent，fortheloadsprojectsofar，thattheanimals，occasionallyrunningagainsteachother，oragainstapointofrock，losetheirbalance，andarethrowndowntheprecipices。IncrossingtheriversIcanwellbelievethatthedifficultymaybeverygreat：atthisseasontherewaslittletrouble，butinthesummertheymustbeveryhazardous。Icanquiteimagine，asSirF。Headdescribes，thedifferentexpressionsofthosewho_have_
　　passedthegulf，andthosewho_are_passing。Ineverheardofanymanbeingdrowned，butwithloadedmulesitfrequentlyhappens。Thearrierotellsyoutoshowyourmulethebestline，andthenallowhertocrossasshelikes：thecargo-muletakesabadline，andisoftenlost。
　　April4th——FromtheRiodelasVacastothePuentedelIncas，halfaday’sjourney。Astherewaspastureforthemules，andgeologyforme，webivouackedhereforthenight。WhenonehearsofanaturalBridge，onepicturestoone’sselfsomedeepandnarrowravine，acrosswhichaboldmassofrockhasfallen；oragreatarchhollowedoutlikethevaultofacavern。Insteadofthis，theIncasBridgeconsistsofacrustofstratifiedshinglecementedtogetherbythedepositsoftheneighbouringhotsprings。
　　Itappears，asifthestreamhadscoopedoutachannelononeside，leavinganoverhangingledge，whichwasmetbyearthandstonesfallingdownfromtheoppositecliff。Certainlyanobliquejunction，aswouldhappeninsuchacase，wasverydistinctononeside。TheBridgeoftheIncasisbynomeansworthyofthegreatmonarchswhosenameitbears。
　　5th——Wehadalongday’srideacrossthecentralridge，fromtheIncasBridgetotheOjosdelAgua，whicharesituatednearthelowest_casucha_
　　ontheChilianside。Thesecasuchasareroundlittletowers，withstepsoutsidetoreachthefloor，whichisraisedsomefeetabovethegroundonaccountofthesnow-drifts。Theyareeightinnumber，andundertheSpanishgovernmentwerekeptduringthewinterwellstoredwithfoodandcharcoal，andeachcourierhadamaster-key。Nowtheyonlyanswerthepurposeofcaves，orratherdungeons。Seatedonsomelittleeminence，theyarenot，however，illsuitedtothesurroundingsceneofdesolation。ThezigzagascentoftheCumbre，orthepartitionofthewaters，wasverysteepandtedious；itsheight，accordingtoMr。Pentland，is12，454feet。Theroaddidnotpassoveranyperpetualsnow，althoughtherewerepatchesofitonbothhands。Thewindonthesummitwasexceedinglycold，butitwasimpossiblenottostopforafewminutestoadmire，againandagain，thecolouroftheheavens，andthebrillianttransparencyoftheatmosphere。
　　Thescenerywasgrand：tothewestwardtherewasafinechaosofmountains，dividedbyprofoundravines。Somesnowgenerallyfallsbeforethisperiodoftheseason，andithasevenhappenedthattheCordillerahavebeenfinallyclosedbythistime。Butweweremostfortunate。Thesky，bynightandbyday，wascloudless，exceptingafewroundlittlemassesofvapour，thatfloatedoverthehighestpinnacles。Ihaveoftenseentheseisletsinthesky，markingthepositionoftheCordillera，whenthefar-distantmountainshavebeenhiddenbeneaththehorizon。