herewehaveaneruptionrelievingandtakingtheplaceofanearthquake，aswouldhavehappenedatConcepcion，accordingtothebeliefofthelowerorders，ifthevolcanoatAntucohadnotbeenclosedbywitchcraft。Twoyearsandthree-quartersafterwards，ValdiviaandChiloewereagainshaken，moreviolentlythanonthe20th，andanislandintheChonosArchipelagowaspermanentlyelevatedmorethaneightfeet。Itwillgiveabetterideaofthescaleofthesephenomena，ifasinthecaseoftheglacierswesupposethemtohavetakenplaceatcorrespondingdistancesinEurope：——
　　thenwouldthelandfromtheNorthSeatotheMediterraneanhavebeenviolentlyshaken，andatthesameinstantoftimealargetractoftheeasterncoastofEnglandwouldhavebeenpermanentlyelevated，togetherwithsomeoutlyingislands，——atrainofvolcanosonthecoastofHollandwouldhaveburstforthinaction，andaneruptiontakenplaceatthebottomofthesea，nearthenorthernextremityofIreland——andlastly，theancientventsofAuvergne，Cantal，andMontd’Orwouldeachhavesentuptotheskyadarkcolumnofsmoke，andhavelongremainedinfierceaction。Twoyearsandthree-quartersafterwards，France，fromitscentretotheEnglishChannel，wouldhavebeenagaindesolatedbyanearthquakeandanislandpermanentlyupraisedintheMediterranean。
　　Thespace，fromunderwhichvolcanicmatteronthe20thwasactuallyerupted，is720milesinoneline，and400milesinanotherlineatrightanglestothefirst：hence，inallprobability，asubterraneanlakeoflavaisherestretchedout，ofnearlydoubletheareaoftheBlackSea。
　　Fromtheintimateandcomplicatedmannerinwhichtheelevatoryanderuptiveforceswereshowntobeconnectedduringthistrainofphenomena，wemayconfidentlycometotheconclusion，thattheforceswhichslowlyandbylittlestartsupliftcontinents，andthosewhichatsuccessiveperiodspourforthvolcanicmatterfromopenorifices，areidentical。Frommanyreasons，Ibelievethatthefrequentquakingsoftheearthonthislineofcoastarecausedbytherendingofthestrata，necessarilyconsequentonthetensionofthelandwhenupraised，andtheirinjectionbyfluidifiedrock。Thisrendingandinjectionwould，ifrepeatedoftenenoughandweknowthatearthquakesrepeatedlyaffectthesameareasinthesamemanner，formachainofhills；——andthelinearislandofS。Mary，whichwasupraisedthricetheheightoftheneighbouringcountry，seemstobeundergoingthisprocess。Ibelievethatthesolidaxisofamountain，differsinitsmannerofformationfromavolcanichill，onlyinthemoltenstonehavingbeenrepeatedlyinjected，insteadofhavingbeenrepeatedlyejected。Moreover，Ibelievethatitisimpossibletoexplainthestructureofgreatmountain-chains，suchasthatoftheCordillera，werethestrata，cappingtheinjectedaxisofplutonicrock，havebeenthrownontheiredgesalongseveralparallelandneighbouringlinesofelevation，exceptonthisviewoftherockoftheaxishavingbeenrepeatedlyinjected，afterintervalssufficientlylongtoallowtheupperpartsorwedgestocoolandbecomesolid；——forifthestratahadbeenthrownintotheirpresenthighlyinclined，vertical，andeveninvertedpositions，byasingleblow，theverybowelsoftheearthwouldhavegushedout；andinsteadofbeholdingabruptmountain-axesofrocksolidifiedundergreatpressure，delugesoflavawouldhaveflowedoutatinnumerablepointsoneverylineofelevation。[2][1]M。AragoinL’Institut，1839，p。337。SeealsoMiers’sChile，vol。i。p。392；alsoLyell’sPrinciplesofGeology，chap。
　　xv。，bookii。
　　[2]Forafullaccountofthevolcanicphenomenawhichaccompaniedtheearthquakeofthe20th，andfortheconclusionsdeduciblefromthem，ImustrefertoVolumeV。oftheGeologicalTransactions。PreviousChapterNextChapterTheVoyageoftheBeagle-Chapter15TheVoyageoftheBeaglebyCharlesDarwinPreviousChapterNextChapterChapter15-PassageoftheCordilleraMARCH7th，1835——WestayedthreedaysatConcepcion，andthensailedforValparaiso。Thewindbeingnortherly，weonlyreachedthemouthoftheharbourofConcepcionbeforeitwasdark。Beingveryneartheland，andafogcomingon，theanchorwasdropped。PresentlyalargeAmericanwhalerappearedalongsideofus；andweheardtheYankeeswearingathismentokeepquiet，whilsthelistenedforthebreakers。CaptainFitzRoyhailedhim，inaloudclearvoice，toanchorwherehethenwas。Thepoormanmusthavethoughtthevoicecamefromtheshore：suchaBabelofcriesissuedatoncefromtheship——everyonehallooingout，“Letgotheanchor！
　　veercable！shortensail！”ItwasthemostlaughablethingIeverheard。
　　Iftheship’screwhadbeenallcaptains，andnomen，therecouldnothavebeenagreateruproaroforders。Weafterwardsfoundthatthematestuttered：
　　Isupposeallhandswereassistinghimingivinghisorders。
　　Onthe11thweanchoredatValparaiso，andtwodaysafterwardsIsetouttocrosstheCordillera。IproceededtoSantiago，whereMr。Caldcleughmostkindlyassistedmeineverypossiblewayinmakingthelittlepreparationswhichwerenecessary。InthispartofChiletherearetwopassesacrosstheAndestoMendoza：theonemostcommonlyused，namely，thatofAconcaguaorUspallata——issituatedsomewaytothenorth；theother，calledthePortillo，istothesouth，andnearer，butmoreloftyanddangerous。
　　March18th——WesetoutforthePortillopass。LeavingSantiagowecrossedthewideburnt-upplainonwhichthatcitystands，andintheafternoonarrivedattheMaypu，oneoftheprincipalriversinChile。Thevalley，atthepointwhereitentersthefirstCordillera，isboundedoneachsidebyloftybarrenmountains；andalthoughnotbroad，itisveryfertile。
　　Numerouscottagesweresurroundedbyvines，andbyorchardsofapple，nectarine，andpeach-trees——theirboughsbreakingwiththeweightofthebeautifulripefruit。Intheeveningwepassedthecustom-house，whereourluggagewasexamined。ThefrontierofChileisbetterguardedbytheCordillera，thanbythewatersofthesea。Thereareveryfewvalleyswhichleadtothecentralranges，andthemountainsarequiteimpassableinotherpartsbybeastsofburden。Thecustom-houseofficerswereverycivil，whichwasperhapspartlyowingtothepassportwhichthePresidentoftheRepublichadgivenme；butImustexpressmyadmirationatthenaturalpolitenessofalmosteveryChileno。Inthisinstance，thecontrastwiththesameclassofmeninmostothercountrieswasstronglymarked。ImaymentionananecdotewithwhichIwasatthetimemuchpleased：wemetnearMendozaalittleandveryfatnegress，ridingastrideonamule。Shehada_goitre_soenormousthatitwasscarcelypossibletoavoidgazingatherforamoment；butmytwocompanionsalmostinstantly，bywayofapology，madethecommonsaluteofthecountrybytakingofftheirhats。WherewouldoneofthelowerorhigherclassesinEurope，haveshownsuchfeelingpolitenesstoapoorandmiserableobjectofadegradedrace？
　　Atnightwesleptatacottage。Ourmanneroftravellingwasdelightfullyindependent。Intheinhabitedpartsweboughtalittlefirewood，hiredpasturefortheanimals，andbivouackedinthecornerofthesamefieldwiththem。Carryinganironpot，wecookedandateoursupperunderacloudlesssky，andknewnotrouble。MycompanionswereMarianoGonzales，whohadformerlyaccompaniedmeinChile，andan“arriero。”withhistenmulesanda“madrina。”Themadrinaorgodmotherisamostimportantpersonage：
　　sheisanoldsteadymare，withalittlebellroundherneck；andwherevershegoes，themules，likegoodchildren，followher。Theaffectionoftheseanimalsfortheirmadrinassavesinfinitetrouble。Ifseverallargetroopsareturnedintoonefieldtograze，inthemorningthemuleteershaveonlytoleadthemadrinasalittleapart，andtinkletheirbells；althoughtheremaybetwoorthreehundredtogether，eachmuleimmediatelyknowsthebellofitsownmadrina，andcomestoher。Itisnearlyimpossibletoloseanoldmule；forifdetainedforseveralhoursbyforce，shewill，bythepowerofsmell，likeadog，trackouthercompanions，orratherthemadrina，for，accordingtothemuleteer，sheisthechiefobjectofaffection。Thefeeling，however，isnotofanindividualnature；forIbelieveIamrightinsayingthatanyanimalwithabellwillserveasamadrina。Inatroopeachanimalcarriesonalevelroad，acargoweighing416poundsmorethan29stone，butinamountainouscountry100poundsless；yetwithwhatdelicateslimlimbs，withoutanyproportionalbulkofmuscle，theseanimalssupportsogreataburden！Themulealwaysappearstomeamostsurprisinganimal。Thatahybridshouldpossessmorereason，memory，obstinacy，socialaffection，powersofmuscularendurance，andlengthoflife，thaneitherofitsparents，seemstoindicatethatarthashereoutdonenature。
　　Ofourtenanimals，sixwereintendedforriding，andfourforcarryingcargoes，eachtakingturnabout。Wecarriedagooddealoffoodincaseweshouldbesnowedup，astheseasonwasratherlateforpassingthePortillo。
　　March19th——Werodeduringthisdaytothelast，andthereforemostelevated，houseinthevalley。Thenumberofinhabitantsbecamescanty；
　　butwhereverwatercouldbebroughtontheland，itwasveryfertile。AllthemainvalleysintheCordilleraarecharacterizedbyhaving，onbothsides，afringeorterraceofshingleandsand，rudelystratified，andgenerallyofconsiderablethickness。Thesefringesevidentlyonceextendedacrossthevalleysandwereunited；andthebottomsofthevalleysinnorthernChile，wheretherearenostreams，arethussmoothlyfilledup。Onthesefringestheroadsaregenerallycarried，fortheirsurfacesareeven，andtheyrise，withaverygentleslopeupthevalleys：hence，also，theyareeasilycultivatedbyirrigation。Theymaybetraceduptoaheightofbetween7000and9000feet，wheretheybecomehiddenbytheirregularpilesofdebris。Atthelowerendormouthsofthevalleys，theyarecontinuouslyunitedtothoseland-lockedplainsalsoformedofshingleatthefootofthemainCordillera，whichIhavedescribedinaformerchapterascharacteristicofthesceneryofChile，andwhichwereundoubtedlydepositedwhentheseapenetratedChile，asitnowdoesthemoresoutherncoasts。NoonefactinthegeologyofSouthAmerica，interestedmemorethantheseterracesofrudely-stratifiedshingle。Theypreciselyresembleincompositionthematterwhichthetorrentsineachvalleywoulddeposit，iftheywerecheckedintheircoursebyanycause，suchasenteringalakeorarmofthesea；
　　butthetorrents，insteadofdepositingmatter，arenowsteadilyatworkwearingawayboththesolidrockandthesealluvialdeposits，alongthewholelineofeverymainvalleyandsidevalley。Itisimpossibleheretogivethereasons，butIamconvincedthattheshingleterraceswereaccumulated，duringthegradualelevationoftheCordillera，bythetorrentsdelivering，atsuccessivelevels，theirdetritusonthebeachheadsoflongnarrowarmsofthesea，firsthighupthevalleys，thenlowerandlowerdownasthelandslowlyrose。Ifthisbeso，andIcannotdoubtit，thegrandandbrokenchainoftheCordillera，insteadofhavingbeensuddenlythrownup，aswastilllatelytheuniversal，andstillisthecommonopinionofgeologists，hasbeenslowlyupheavedinmass，inthesamegradualmannerasthecoastsoftheAtlanticandPacifichaverisenwithintherecentperiod。AmultitudeoffactsinthestructureoftheCordillera，onthisviewreceiveasimpleexplanation。
　　Theriverswhichflowinthesevalleysoughtrathertobecalledmountain-torrents。
　　Theirinclinationisverygreat，andtheirwaterthecolourofmud。TheroarwhichtheMaypumade，asitrushedoverthegreatroundedfragments，waslikethatofthesea。Amidstthedinofrushingwaters，thenoisefromthestones，astheyrattledoneoveranother，wasmostdistinctlyaudibleevenfromadistance。Thisrattlingnoise，nightandday，maybeheardalongthewholecourseofthetorrent。Thesoundspokeeloquentlytothegeologist；thethousandsandthousandsofstones，which，strikingagainsteachother，madetheonedulluniformsound，wereallhurryinginonedirection。
　　Itwaslikethinkingontime，wheretheminutethatnowglidespastisirrevocable。Sowasitwiththesestones；theoceanistheireternity，andeachnoteofthatwildmusictoldofonemoresteptowardstheirdestiny。
　　Itisnotpossibleforthemindtocomprehend，exceptbyaslowprocess，anyeffectwhichisproducedbyacauserepeatedsooften，thatthemultiplieritselfconveysanidea，notmoredefinitethanthesavageimplieswhenhepointstothehairsofhishead。AsoftenasIhaveseenbedsofmud，sand，andshingle，accumulatedtothethicknessofmanythousandfeet，Ihavefeltinclinedtoexclaimthatcauses，suchasthepresentriversandthepresentbeaches，couldneverhavegrounddownandproducedsuchmasses。But，ontheotherhand，whenlisteningtotherattlingnoiseofthesetorrents，andcallingtomindthatwholeracesofanimalshavepassedawayfromthefaceoftheearth，andthatduringthiswholeperiod，nightandday，thesestoneshavegonerattlingonwardsintheircourse，Ihavethoughttomyself，cananymountains，anycontinent，withstandsuchwaste？
　　Inthispartofthevalley，themountainsoneachsidewerefrom3000
　　to6000or8000feethigh，withroundedoutlinesandsteepbareflanks。
　　Thegeneralcolouroftherockwasdullishpurple，andthestratificationverydistinct。Ifthescenerywasnotbeautiful，itwasremarkableandgrand。Wemetduringthedayseveralherdsofcattle，whichmenweredrivingdownfromthehighervalleysintheCordillera。Thissignoftheapproachingwinterhurriedoursteps，morethanwasconvenientforgeologizing。Thehousewherewesleptwassituatedatthefootofamountain，onthesummitofwhicharetheminesofS。PedrodeNolasko。SirF。Headmarvelshowmineshavebeendiscoveredinsuchextraordinarysituations，asthebleaksummitofthemountainofS。PedrodeNolasko。Inthefirstplace，metallicveinsinthiscountryaregenerallyharderthanthesurroundingstrata：