第64章

类别:其他 作者:Charles Darwin字数:5955更新时间:18/12/21 17:23:57
[2]Observa。sobreelClimadeLima,p。67——Azara’sTravels,vol。i。p。381——Ulloa’sVoyage,vol。ii。p。28——Burchell’sTravels,vol。ii。p。524——Webster’sDescriptionoftheAzores,p。124—— Voyageal’IsledeFranceparunOfficerduRoi,tom。i。p。248—— DescriptionofSt。Helena,p。123。 [3]Temple,inhistravelsthroughUpperPeru,orBolivia,ingoingfromPotositoOruro,says,“IsawmanyIndianvillagesordwellingsinruins,upeventotheverytopsofthemountains,attestingaformerpopulationwherenowallisdesolate。”Hemakessimilarremarksinanotherplace;butIcannottellwhetherthisdesolationhasbeencausedbyawantofpopulation,orbyanalteredconditionoftheland。 [4]Edinburgh,Phil。Journ。,Jan。,1830,p。74; andApril,1830,p。258——alsoDaubenyonVolcanoes,p。438;andBengalJourn。,vol。vii。p。324。 [5]PoliticalEssayontheKingdomofNewSpain,vol。iv。p。199。 [6]AsimilarinterestingcaseisrecordedintheMadrasMedicalQuart。Journ。,1839,p。340。Dr。Ferguson,inhisadmirablePaper(see9thvol。ofEdinburghRoyalTrans。),showsclearlythatthepoisonisgeneratedinthedryingprocess;andhencethatdryhotcountriesareoftenthemostunhealthy。PreviousChapterNextChapterTheVoyageoftheBeagle-Chapter17TheVoyageoftheBeaglebyCharlesDarwinPreviousChapterNextChapterChapter17-GalapagosArchipelagoSEPTEMBER15th——Thisarchipelagoconsistsoftenprincipalislands,ofwhichfiveexceedtheothersinsize。TheyaresituatedundertheEquator,andbetweenfiveandsixhundredmileswestwardofthecoastofAmerica。 Theyareallformedofvolcanicrocks;afewfragmentsofgranitecuriouslyglazedandalteredbytheheat,canhardlybeconsideredasanexception。 Someofthecraters,surmountingthelargerislands,areofimmensesize,andtheyrisetoaheightofbetweenthreeandfourthousandfeet。Theirflanksarestuddedbyinnumerablesmallerorifices。Iscarcelyhesitatetoaffirm,thattheremustbeinthewholearchipelagoatleasttwothousandcraters。Theseconsisteitheroflavaorscoriae,oroffinely-stratified,sandstone-liketuff。Mostofthelatterarebeautifullysymmetrical;theyowetheirorigintoeruptionsofvolcanicmudwithoutanylava:itisaremarkablecircumstancethateveryoneofthetwenty-eighttuff-craterswhichwereexamined,hadtheirsouthernsideseithermuchlowerthantheothersides,orquitebrokendownandremoved。Asallthesecratersapparentlyhavebeenformedwhenstandinginthesea,andasthewavesfromthetradewindandtheswellfromtheopenPacifichereunitetheirforcesonthesoutherncoastsofalltheislands,thissingularuniformityinthebrokenstateofthecraters,composedofthesoftandyieldingtuff,iseasilyexplained。 Consideringthattheseislandsareplaceddirectlyundertheequator,theclimateisfarfrombeingexcessivelyhot;thisseemschieflycausedbythesingularlylowtemperatureofthesurroundingwater,broughtherebythegreatsouthern[map] Polarcurrent。Exceptingduringoneshortseason,verylittlerainfalls,andeventhenitisirregular;butthecloudsgenerallyhanglow。Hence,whilstthelowerpartsoftheislandsareverysterile,theupperparts,ataheightofathousandfeetandupwards,possessadampclimateandatolerablyluxuriantvegetation。Thisisespeciallythecaseonthewindwardsidesoftheislands,whichfirstreceiveandcondensethemoisturefromtheatmosphere。 Inthemorning(17th)welandedonChathamIsland,which,liketheothers,riseswithatameandroundedoutline,brokenhereandtherebyscatteredhillocks,theremainsofformercraters。Nothingcouldbelessinvitingthanthefirstappearance。Abrokenfieldofblackbasalticlava,thrownintothemostruggedwaves,andcrossedbygreatfissures,iseverywherecoveredbystunted,sun-burntbrushwood,whichshowslittlesignsoflife。 Thedryandparchedsurface,beingheatedbythenoon-daysun,gavetotheairacloseandsultryfeeling,likethatfromastove:wefanciedeventhatthebushessmeltunpleasantly。AlthoughIdiligentlytriedtocollectasmanyplantsaspossible,Isucceededingettingveryfew;andsuchwretched-lookinglittleweedswouldhavebetterbecomeanarcticthananequatorialFlora。Thebrushwoodappears,fromashortdistance,asleaflessasourtreesduringwinter;anditwassometimebeforeIdiscoveredthatnotonlyalmosteveryplantwasnowinfullleaf,butthatthegreaternumberwereinflower。ThecommonestbushisoneoftheEuphorbiaceae: anacaciaandagreatodd-lookingcactusaretheonlytreeswhichaffordanyshade。Aftertheseasonofheavyrains,theislandsaresaidtoappearforashorttimepartiallygreen。ThevolcanicislandofFernandoNoronha,placedinmanyrespectsundernearlysimilarconditions,istheonlyothercountrywhereIhaveseenavegetationatalllikethisoftheGalapagosIslands。 TheBeaglesailedroundChathamIsland,andanchoredinseveralbays。 OnenightIsleptonshoreonapartoftheisland,whereblacktruncatedconeswereextraordinarilynumerous:fromonesmalleminenceIcountedsixtyofthem,allsurmountedbycratersmoreorlessperfect。Thegreaternumberconsistedmerelyofaringofredscoriaeorslags,cementedtogether: andtheirheightabovetheplainoflavawasnotmorethanfromfiftytoahundredfeet;nonehadbeenverylatelyactive。Theentiresurfaceofthispartoftheislandseemstohavebeenpermeated,likeasieve,bythesubterraneanvapours:hereandtherethelava,whilstsoft,hasbeenblownintogreatbubbles;andinotherparts,thetopsofcavernssimilarlyformedhavefallenin,leavingcircularpitswithsteepsides。Fromtheregularformofthemanycraters,theygavetothecountryanartificialappearance,whichvividlyremindedmeofthosepartsofStaffordshire,wherethegreatiron-foundriesaremostnumerous。Thedaywasglowinghot,andthescramblingovertheroughsurfaceandthroughtheintricatethickets,wasveryfatiguing;butIwaswellrepaidbythestrangeCyclopeanscene。 AsIwaswalkingalongImettwolargetortoises,eachofwhichmusthaveweighedatleasttwohundredpounds:onewaseatingapieceofcactus,andasIapproached,itstaredatmeandslowlywalkedaway;theothergaveadeephiss,anddrewinitshead。Thesehugereptiles,surroundedbytheblacklava,theleaflessshrubs,andlargecacti,seemedtomyfancylikesomeantediluviananimals。Thefewdull-colouredbirdscarednomoreformethantheydidforthegreattortoises。 23rd——TheBeagleproceededtoCharlesIsland。Thisarchipelagohaslongbeenfrequented,firstbythebucaniers,andlatterlybywhalers,butitisonlywithinthelastsixyears,thatasmallcolonyhasbeenestablishedhere。Theinhabitantsarebetweentwoandthreehundredinnumber;theyarenearlyallpeopleofcolour,whohavebeenbanishedforpoliticalcrimesfromtheRepublicoftheEquator,ofwhichQuitoisthecapital。Thesettlementisplacedaboutfourandahalfmilesinland,andataheightprobablyofathousandfeet。Inthefirstpartoftheroadwepassedthroughleaflessthickets,asinChathamIsland。Higherup,thewoodsgraduallybecamegreener;andassoonaswecrossedtheridgeoftheisland,wewerecooledbyafinesoutherlybreeze,andoursightrefreshedbyagreenandthrivingvegetation。Inthisupperregioncoarsegrassesandfernsabound;buttherearenotree-ferns:Isawnowhereanymemberofthepalmfamily,whichisthemoresingular,as360milesnorthward,CocosIslandtakesitsnamefromthenumberofcocoa-nuts。Thehousesareirregularlyscatteredoveraflatspaceofground,whichiscultivatedwithsweetpotatoesandbananas。Itwillnoteasilybeimaginedhowpleasantthesightofblackmudwastous,afterhavingbeensolong,accustomedtotheparchedsoilofPeruandnorthernChile。Theinhabitants,althoughcomplainingofpoverty,obtain,withoutmuchtrouble,themeansofsubsistence。 Inthewoodstherearemanywildpigsandgoats;butthestaplearticleofanimalfoodissuppliedbythetortoises。Theirnumbershaveofcoursebeengreatlyreducedinthisisland,butthepeopleyetcountontwodays’ huntinggivingthemfoodfortherestoftheweek。Itissaidthatformerlysinglevesselshavetakenawayasmanyassevenhundred,andthattheship’scompanyofafrigatesomeyearssincebroughtdowninonedaytwohundredtortoisestothebeach。 September29th——Wedoubledthesouth-westextremityofAlbemarleIsland,andthenextdaywerenearlybecalmedbetweenitandNarboroughIsland。Botharecoveredwithimmensedelugesofblacknakedlava,whichhaveflowedeitherovertherimsofthegreatcaldrons,likepitchovertherimofapotinwhichithasbeenboiled,orhaveburstforthfromsmallerorificesontheflanks;intheirdescenttheyhavespreadovermilesofthesea-coast。Onbothoftheseislands,eruptionsareknowntohavetakenplace;andinAlbemarle,wesawasmalljetofsmokecurlingfromthesummitofoneofthegreatcraters。IntheeveningweanchoredinBank’sCove,inAlbemarleIsland。ThenextmorningIwentoutwalking。 Tothesouthofthebrokentuff-crater,inwhichtheBeaglewasanchored,therewasanotherbeautifullysymmetricaloneofanellipticform;itslongeraxiswasalittlelessthanamile,anditsdepthabout500feet。 Atitsbottomtherewasashallowlake,inthemiddleofwhichatinycraterformedanislet。Thedaywasoverpoweringlyhot,andthelakelookedclearandblue:Ihurrieddownthecinderyslope,and,chokedwithdust,eagerlytastedthewater——but,tomysorrow,Ifounditsaltasbrine。 Therocksonthecoastaboundedwithgreatblacklizards,betweenthreeandfourfeetlong;andonthehills,anuglyyellowish-brownspecieswasequallycommon。Wesawmanyofthislatterkind,someclumsilyrunningoutoftheway,andothersshufflingintotheirburrows。Ishallpresentlydescribeinmoredetailthehabitsofboththesereptiles。ThewholeofthisnorthernpartofAlbemarleIslandismiserablysterile。 October8th——WearrivedatJamesIsland:thisisland,aswellasCharlesIsland,werelongsincethusnamedafterourkingsoftheStuartline。Mr。Bynoe,myself,andourservantswerelefthereforaweek,withprovisionsandatent,whilsttheBeaglewentforwater。WefoundhereapartyofSpaniards,whohadbeensentfromCharlesIslandtodryfish,andtosalttortoise-meat。Aboutsixmilesinland,andattheheightofnearly2000feet,ahovelhadbeenbuiltinwhichtwomenlived,whowereemployedincatchingtortoises,whilsttheotherswerefishingonthecoast。 Ipaidthispartytwovisits,andsleptthereonenight。Asintheotherislands,thelowerregionwascoveredbynearlyleaflessbushes,butthetreeswerehereofalargergrowththanelsewhere,severalbeingtwofeetandsomeeventwofeetnineinchesindiameter。Theupperregionbeingkeptdampbytheclouds,supportsagreenandflourishingvegetation。Sodampwastheground,thattherewerelargebedsofacoarsecyperus,inwhichgreatnumbersofaverysmallwater-raillivedandbred。Whilestayinginthisupperregion,welivedentirelyupontortoise-meat:thebreast-plateroasted(astheGauchosdo_carneconcuero_),withthefleshonit,isverygood;andtheyoungtortoisesmakeexcellentsoup;butotherwisethemeattomytasteisindifferent。 OnedayweaccompaniedapartyoftheSpaniardsintheirwhale-boattoasalina,orlakefromwhichsaltisprocured。Afterlanding,wehadaveryroughwalkoveraruggedfieldofrecentlava,whichhasalmostsurroundedatuff-crater,atthebottomofwhichthesalt-lakelies。Thewaterisonlythreeorfourinchesdeep,andrestsonalayerofbeautifullycrystallized,whitesalt。Thelakeisquitecircular,andisfringedwithaborderofbrightgreensucculentplants;thealmostprecipitouswallsofthecraterareclothedwithwood,sothatthescenewasaltogetherbothpicturesqueandcurious。Afewyearssince,thesailorsbelongingtoasealing-vesselmurderedtheircaptaininthisquietspot;andwesawhisskulllyingamongthebushes。 Duringthegreaterpartofourstayofaweek,theskywascloudless,andifthetrade-windfailedforanhour,theheatbecameveryoppressive。 Ontwodays,thethermometerwithinthetentstoodforsomehoursat93 degs。;butintheopenair,inthewindandsun,atonly85degs。Thesandwasextremelyhot;thethermometerplacedinsomeofabrowncolourimmediatelyroseto137degs。,andhowmuchabovethatitwouldhaverisen,Idonotknow,foritwasnotgraduatedanyhigher。Theblacksandfeltmuchhotter,sothateveninthickbootsitwasquitedisagreeabletowalkoverit。 Thenaturalhistoryoftheseislandsiseminentlycurious,andwelldeservesattention。Mostoftheorganicproductionsareaboriginalcreations,foundnowhereelse;thereisevenadifferencebetweentheinhabitantsofthedifferentislands;yetallshowamarkedrelationshipwiththoseofAmerica,thoughseparatedfromthatcontinentbyanopenspaceofocean,between500and600milesinwidth。Thearchipelagoisalittleworldwithinitself,orratherasatelliteattachedtoAmerica,whenceithasderivedafewstraycolonists,andhasreceivedthegeneralcharacterofitsindigenousproductions。Consideringthesmallsizeoftheislands,wefeelthemoreastonishedatthenumberoftheiraboriginalbeings,andattheirconfinedrange。Seeingeveryheightcrownedwithitscrater,andtheboundariesofmostofthelava-streamsstilldistinct,weareledtobelievethatwithinaperiodgeologicallyrecenttheunbrokenoceanwasherespreadout。Hence,bothinspaceandtime,weseemtobebroughtsomewhatneartothatgreatfact——thatmysteryofmysteries——thefirstappearanceofnewbeingsonthisearth。