第3章

Forthefirstseventy-fivemilesnorthofValparaisoIfollowedthecoast- road，andthroughoutthisspaceIobservedinnumerablemassesofupraisedshells。AboutQuinterothereareimmenseaccumulations(workedforlime)oftheMesodesmadonaciforme，packedinsandyearth;theyaboundchieflyaboutfifteenfeetabovehigh-water，butshellsareherefound，accordingtoMr。 Miers，toaheightof500feet，andatadistanceofthreeleaguesfromthecoast(“TravelsinChile“volume1pages395，458。Ireceivedseveralsimilaraccountsfromtheinhabitants，andwasassuredthattherearemanyshellsontheplainofCasaBlanca，betweenValparaisoandSantiago，attheheightof800feet。)：Iherenoticedbarnaclesadheringtotherocksthreeorfourfeetabovethehighesttides。IntheneighbourhoodofPlazillaandCatapilco，atheightsofbetweentwohundredandthreehundredfeet，thenumberofcomminutedshells，withsomeperfectones，especiallyoftheMesodesma，packedinlayers，wastrulyimmense：thelandatPlazillahadevidentlyexistedasabay，withabruptrockymassesrisingoutofit，preciselyliketheisletsinthebrokenbaysnowindentingthiscoast。OnbothsidesoftheriversLigua，Longotomo，Guachen，andQuilimari，thereareplainsofgravelabouttwohundredfeetinheight，inmanypartsabsolutelycoveredwithshells。ClosetoConchalee，agravel-plainisfrontedbyalowerandsimilarplainaboutsixtyfeetinheight，andthisagainisseparatedfromthebeachbyawidetractoflowland：thesurfacesofallthreeplainsorterraceswerestrewedwithvastnumbersoftheConcholepas，Mesodesma，anexistingVenus，andotherstillexistinglittoralshells。ThetwoupperterracescloselyresembleinminiaturetheplainsofPatagonia;andlikethemarefurrowedbydry，flat-bottomed，windingvalleys。NorthwardofthisplaceIturnedinward;andthereforefoundnomoreshells：butthevalleysofChuapa，Illapel，andLimari，areboundedbygravel-cappedplains，oftenincludingalowerterracewithin。 Theseplainssendbay-likearmsbetweenandintothesurroundinghills;andtheyarecontinuouslyunitedwithotherextensivegravel-cappedplains，separatingthecoastmountain-rangesfromtheCordillera。 COQUIMBO。 Anarrowfringe-likeplain，gentlyinclinedtowardsthesea，hereextendsforelevenmilesalongthecoast，witharmsstretchingupbetweenthecoast-mountains，andlikewiseupthevalleyofCoquimbo：atitssouthernextremityitisdirectlyconnectedwiththeplainofLimari，outofwhichhillsabruptlyriselikeislets，andotherhillsprojectlikeheadlandsonacoast。Thesurfaceofthefringe-likeplainappearslevel，butdiffersinsensiblyinheight，andgreatlyincomposition，indifferentparts。 AtthemouthofthevalleyofCoquimbo，thesurfaceconsistswhollyofgravel，andstandsfrom300to350feetabovethelevelofthesea，beingaboutonehundredfeethigherthaninotherparts。Intheseotherandlowerpartsthesuperficialbedsconsistofcalcareousmatter，andrestonancienttertiarydepositshereaftertobedescribed。Theuppermostcalcareouslayeriscream-coloured，compact，smooth-fractured，sub- stalactiform，andcontainssomesand，earthymatter，andrecentshells。Itlieson，andsendswedge-likeveinsinto，amuchmorefriable，calcareous，tuff-likevariety;andbothrestonamassabouttwentyfeetinthickness，formedoffragmentsofrecentshells，withafewwholeones，andwithsmallpebblesfirmlycementedtogether。(Inmanyrespectsthisupperhard，andtheunderlyingmorefriable，varieties，resemblethegreatsuperficialbedsatKingGeorge’sSoundinAustralia，whichIhavedescribedinmy“GeologicalObservationsonVolcanicIslands。”Therecouldbelittledoubtthattheupperlayerstherehavebeenhardenedbytheactionofrainonthefriable，calcareousmatter，andthatthewholemasshasoriginatedinthedecayofminutelycomminutedsea-shellsandcorals。)Thislatterrockiscalledbytheinhabitantslosa，andisusedforbuilding：inmanypartsitisdividedintostrata，whichdipatanangleoftendegreesseaward，andappearasiftheyhadoriginallybeenheapedinsuccessivelayers(asmaybeseenoncoral-reefs)onasteepbeach。Thisstoneisremarkablefrombeinginpartsentirelyformedofempty，pellucidcapsulesorcellsofcalcareousmatter，ofthesizeofsmallseeds：aseriesofspecimensunequivocallyshowedthatallthesecapsulesoncecontainedminuteroundedfragmentsofshellswhichhavesincebeengraduallydissolvedbywaterpercolatingthroughthemass。(IhaveincidentallydescribedthisrockintheaboveworkonVolcanicIslands。) Theshellsembeddedinthecalcareousbedsformingthesurfaceofthisfringe-likeplain，attheheightoffrom200to250feetabovethesea，consistof：—— 1。Venusopaca。 2。MuliniaByronensis。 3。Pectenpurpuratus。 4。Mesodesmadonaciforme。 5。Turritellacingulata。 6。Monoceroscostatum。 7。ConcholepasPeruviana。 8。Trochus(commonValparaisospecies)。 9。CalyptraeaByronensis。 Althoughthesespeciesareallrecent，andareallfoundintheneighbouringsea，yetIwasparticularlystruckwiththedifferenceintheproportionalnumbersoftheseveralspecies，andofthosenowcastuponthepresentbeach。IfoundonlyonespecimenoftheConcholepas，andthePectenwasveryrare，thoughboththeseshellsarenowthecommonestkinds，withtheexception，perhaps，oftheCalyptraearadians，ofwhichIdidnotfindoneinthecalcareousbeds。Iwillnotpretendtodeterminehowfarthisdifferenceintheproportionalnumbersdependsontheageofthedeposit，andhowfaronthedifferenceinnaturebetweenthepresentsandybeachesandthecalcareousbottom，onwhichtheembeddedshellsmusthavelived。 (DIAGRAM8——SECTIONOFPLAINOFCOQUIMBO。 SectionthroughPlainB-BandRavineA。 Surfaceofplain252feetabovesea。 A。Stratifiedsand，withrecentshellsinsameproportionsasonthebeach，halffillinguparavine。 B。Surfaceofplain，withscatteredshellsinnearlysameproportionsasonthebeach。 C。Uppercalcareousbed，andD。Lowercalcareoussandybed(Losa)，bothwithrecentshells，butnotinsameproportionsasonthebeach。 E。Upperferrugino-sandyoldtertiarystratum，andF。Loweroldtertiarystratum，bothwithall，ornearlyall，extinctshells。) Onthebaresurfaceofthecalcareousplain，orinathincoveringofsand，therewerelying，ataheightfrom200to252feet，manyrecentshells，whichhadamuchfresherappearancethantheembeddedones：fragmentsoftheConcholepas，andofthecommonMytilus，stillretainingatingeofitscolour，werenumerous，andaltogethertherewasmanifestlyacloserapproachinproportionalnumberstothosenowlyingonthebeach。Inamassofstratified，slightlyagglutinatedsand，whichinsomeplacescoversupthelowerhalfoftheseawardescarpmentoftheplain，theincludedshellsappearedtobeinexactlythesameproportionalnumberswiththoseonthebeach。Ononesideofasteep-sidedravine，cuttingthroughtheplainbehindHerraduraBay，Iobservedanarrowstripofstratifiedsand，containingsimilarshellsinsimilarproportionalnumbers;asectionoftheravineisrepresentedinDiagram8，whichservesalsotoshowthegeneralcompositionoftheplain。Imentionthiscaseoftheravinechieflybecausewithouttheevidenceofthemarineshellsinthesand，anyonewouldhavesupposedthatithadbeenhollowedoutbysimplealluvialaction。 Theescarpmentofthefringe-likeplain，whichstretchesforelevenmilesalongthecoast，isinsomepartsfrontedbytwoorthreenarrow，step- formedterraces，oneofwhichatHerraduraBayexpandsintoasmallplain。 Itssurfacewasthereformedofgravel，cementedtogetherbycalcareousmatter;andoutofitIextractedthefollowingrecentshells，whichareinamoreperfectconditionthanthosefromtheupperplain：—— 1。Calyptraearadians。 2。Turritellacingulata。 3。OlivaPeruviana。 4。Murexlabiosus，var。 5。Nassa(identicalwithalivingspecies)。 6。SolenDombeiana。 7。Pectenpurpuratus。 8。VenusChilensis。 9。Amphidesmarugulosum。ThesmallirregularwrinklesoftheposteriorpartofthisshellareratherstrongerthanintherecentspecimensofthisspeciesfromCoquimbo。(G。B。Sowerby。) 10。Balanus(identicalwithlivingspecies)。 Onthesyeniticridge，whichformsthesouthernboundaryofHerraduraBayandPlain，IfoundtheConcholepasandTurritellacingulata(mostlyinfragments)，attheheightof242feetabovethesea。Icouldnothavetoldthattheseshellshadnotformerlybeenbroughtupbyman，ifIhadnotfoundoneverysmallmassofthemcementedtogetherinafriablecalcareoustuff。Imentionthisfactmoreparticularly，becauseIcarefullylooked，inmanyapparentlyfavourablespots，atlesserheightsonthesideofthisridge，andcouldnotfindeventhesmallestfragmentofashell。Thisisonlyoneinstanceoutofmany，provingthattheabsenceofsea-shellsonthesurface，thoughinmanyrespectsinexplicable，isanargumentofverylittleweightinoppositiontootherevidenceontherecentelevationoftheland。ThehighestpointinthisneighbourhoodatwhichIfoundupraisedshellsofexistingspecieswasonaninlandcalcareousplain，attheheightof252feetabovethesea。 ItwouldappearfromMr。Caldcleugh’sresearches，thatarisehastakenplaceherewithinthelastcenturyandahalf(“ProceedingsoftheGeologicalSociety“volume2page446。);andasnosuddenchangeoflevelhasbeenobservedduringthenotverysevereearthquakes，whichhaveoccasionallyoccurredhere，therisinghasprobablybeenslow，likethatnow，orquitelately，inprogressatChiloeandatValparaiso：therearethreewell-knownrocks，calledthePelicans，whichin1710，accordingtoFeuillee，wereafleurd’eau，butnowaresaidtostandtwelvefeetabovelow-watermark：thespring-tidesrisehereonlyfivefeet。Thereisanotherrock，nowninefeetabovehigh-watermark，whichinthetimeofFrezierandFeuilleeroseonlyfiveorsixfeetoutofwater。Mr。Caldcleugh，Imayadd，alsoshows(andIreceivedsimilaraccounts)thattherehasbeenaconsiderabledecreaseinthesoundingsduringthelasttwelveyearsintheBaysofCoquimbo，Concepcion，Valparaiso，andGuasco;butasinthesecasesitisnearlyimpossibletodistinguishbetweentheaccumulationofsedimentandtheupheavementofthebottom，Ihavenotenteredintoanydetails。 VALLEYOFCOQUIMBO。 (FIGURE9。EASTANDWESTSECTIONTHROUGHTHETERRACESATCOQUIMBO，WHERE THEYDEBOUCHFROMTHEVALLEY，ANDFRONTTHESEA。 Verticalscale1/10ofinchto100feet：horizontalscalemuchcontracted。 Heightofterraceinfeetfromeast(high)towest(low)： TerraceF。364 TerraceE。302 TerraceD。showndotted，heightnotgiven。 TerraceC。120 TerraceB。70 TerraceA。25slopingdowntolevelofseaatTownofCoquimbo。) Thenarrowcoast-plainsends，asbeforestated，anarm，ormorecorrectlyafringe，onbothsides，butchieflyonthesouthernside，severalmilesupthevalley。Thesefringesarewornintostepsorterraces，whichpresentamostremarkableappearance，andhavebeencompared(thoughnotverycorrectly)byCaptainBasilHall，totheparallelroadsofGlenRoyinScotland：theiroriginhasbeenablydiscussedbyMr。Lyell。(“PrinciplesofGeology“1steditionvolume3page131。)ThefirstsectionwhichIwillgive(Figure9)，isnotdrawnacrossthevalley，butinaneastandwestlineatitsmouth，wherethestep-formedterracesdebouchandpresenttheirverygentlyinclinedsurfacestowardsthePacific。 Thebottomplain(A)isaboutamileinwidth，andrisesquiteinsensiblyfromthebeachtoaheightoftwenty-fivefeetatthefootofthenextplain;itissandy，andabundantlystrewedwithshells。 PlainorterraceBisofsmallextent，andisalmostconcealedbythehousesofthetown，asislikewisetheescarpmentofterraceC。Onbothsidesofaravine，twomilessouthofthetown，therearetwolittleterraces，oneabovetheother，evidentlycorrespondingwithBandC;andonthemmarineremainsofthespeciesalreadyenumeratedwereplentiful。 TerraceEisverynarrow，butquitedistinctandlevel;alittlesouthwardofthetownthereweretracesofaterraceDintermediatebetweenEandC。 TerraceFispartofthefringe-likeplain，whichstretchesfortheelevenmilesalongthecoast;itisherecomposedofshingle，andis100feethigherthanwherecomposedofcalcareousmatter。Thisgreaterheightisobviouslyduetothequantityofshingle，whichatsomeformerperiodhasbeenbroughtdownthegreatvalleyofCoquimbo。 ConsideringthemanyshellsstrewedovertheterracesA，B，andC，andafewmilessouthwardonthecalcareousplain，whichiscontinuouslyunitedwiththeupperstep-likeplainF，therecannot，Iapprehend，beanydoubt，thatthesesixterraceshavebeenformedbytheactionofthesea;andthattheirfiveescarpmentsmarksomanyperiodsofcomparativerestintheelevatorymovement，duringwhichtheseaworeintotheland。TheelevationbetweentheseperiodsmayhavebeensuddenandonANAVERAGEnotmorethanseventy-twofeeteachtime，oritmayhavebeengradualandinsensiblyslow。Fromtheshellsonthethreelowerterraces，andontheupperone，andImayaddonthethreegravel-cappedterracesatConchalee，beingalllittoralandsub-littoralspecies，andfromtheanalogicalfactsgivenatValparaiso，andlastlyfromtheevidenceofaslowrisinglatelyorstillinprogresshere，itappearstomefarmoreprobablethatthemovementhasbeenslow。Theexistenceofthesesuccessiveescarpments，oroldcliff- lines，isinanotherrespecthighlyinstructive，fortheyshowperiodsofcomparativerestintheelevatorymovement，andofdenudation，whichwouldneverevenhavebeensuspectedfromacloseexaminationofmanymilesofcoastsouthwardofCoquimbo。 (FIGURE10。NORTHANDSOUTHSECTIONACROSSTHEVALLEYOFCOQUIMBO。 >FromnorthF(high)throughE？，D，C，B，A(low)，B？，C，D？，E，F(high)。 Verticalscale1/10ofinchto100feet：horizontalscalemuchcontracted。 Terracesmarkedwith？donotoccuronthatsideofthevalley，andareintroducedonlytomakethediagrammoreintelligible。Ariverandbottom- plainofvalleyC，E，andF，onthesouthsideofvalley，arerespectively，197，377，and420feetabovethelevelofthesea。 AA。Thebottomofthevalley，believedtobe100feetabovethesea：itiscontinuouslyunitedwiththelowestplainAofFigure9。 B。Thisterracehigherupthevalleyexpandsconsiderably;seawarditissoonlost，itsescarpmentbeingunitedwiththatofC：itisnotdevelopedatallonthesouthsideofthevalley。 C。Thisterrace，likethelast，isconsiderablyexpandedhigherupthevalley。ThesetwoterracesapparentlycorrespondwithBandCofFigure9。 Disnotwelldevelopedinthelineofthissection;butseawarditexpandsintoaplain：itisnotpresentonthesouthsideofthevalley;butitismetwith，asstatedundertheformersection，alittlesouthofthetown。 Eiswelldevelopedonthesouthside，butabsentonthenorthsideofthevalley：thoughnotcontinuouslyunitedwithEofFigure9，itapparentlycorrespondswithit。 F。Thisisthesurface-plain，andiscontinuouslyunitedwiththatwhichstretcheslikeafringealongthecoast。Inascendingthevalleyitgraduallybecomesnarrower，andisatlast，atthedistanceofabouttenmilesfromthesea，reducedtoarowofflat-toppedpatchesonthesidesofthemountains。Noneofthelowerterracesextendsofarupthevalley。) WecomenowtotheterracesontheoppositesidesoftheeastandwestvalleyofCoquimbo：thesectioninFigure10istakeninanorthandsouthlineacrossthevalleyatapointaboutthreemilesfromthesea。ThevalleymeasuredfromtheedgesoftheescarpmentsoftheupperplainFFisaboutamileinwidth;butfromthebasesoftheboundingmountainsitisfromthreetofourmileswide。Theterracesmarkedwithaninterrogativedonotexistonthatsideofthevalley，butareintroducedmerelytorenderthediagrammoreintelligible。 Thesefiveterracesareformedofshingleandsand;threeofthem，asmarkedbyCaptainB。Hall(namely，B，C，andF)，aremuchmoreconspicuousthantheothers。Fromthemarineremainscopiouslystrewedatthemouthofthevalleyonthelowerterraces，andsouthwardofthetownontheupperone，theyare，asbeforeremarked，undoubtedlyofmarineorigin;butwithinthevalley，andthisfactwelldeservesnotice，atadistanceoffromonlyamileandahalftothreeorfourmilesfromthesea，Icouldnotfindevenafragmentofashell。 ONTHEINCLINATIONOFTHETERRACESOFCOQUIMBO，ANDONTHEUPPERANDBASAL EDGESOFTHEIRESCARPMENTSNOTBEINGHORIZONTAL。 Thesurfacesoftheseterracesslopeinaslightdegree，asshownbythesectionsinFigures9and10takenconjointly，bothtowardsthecentreofthevalley，andseawardstowardsitsmouth。Thisdoubleordiagonalinclination，whichisnotthesameintheseveralterraces，is，asweshallimmediatelysee，ofsimpleexplanation。Thereare，however，someotherpointswhichatfirstappearbynomeansobvious，——namely，first，thateachterrace，takeninitswholebreadthfromthesummit-edgeofoneescarpmenttothebaseofthataboveit，andfollowedupthevalley，isnothorizontal;norhavetheseveralterraces，whenfollowedupthevalley，allthesameinclination;thusIfoundtheterracesC，E，andF，measuredatapointabouttwomilesfromthemouthofthevalley，stoodseverallybetweenfifty-sixtoseventy-sevenfeethigherthanatthemouth。Again，ifwelooktoanyonelineofclifforescarpment，neitheritssummit-edgenoritsbaseishorizontal。Onthetheoryoftheterraceshavingbeenformedduringaslowandequableriseoftheland，withasmanyintervalsofrestasthereareescarpments，itappearsatfirstverysurprisingthathorizontallinesofsomekindshouldnothavebeenleftontheland。 Thedirectionofthediagonalinclinationinthedifferentterracesbeingdifferent，——insomebeingdirectedmoretowardsthemiddleofthevalley，inothersmoretowardsitsmouth，——naturallyfollowsontheviewofeachterrace，beinganaccumulationofsuccessivebeach-linesroundbays，whichmusthavebeenofdifferentformsandsizeswhenthelandstoodatdifferentlevels：forifwelooktotheactualbeachofanarrowcreek，itsslopeisdirectedtowardsthemiddle;whereas，inanopenbay，orslightconcavityonacoast，theslopeistowardsthemouth，thatis，almostdirectlyseaward;henceasabayaltersinformandsize，sowillthedirectionoftheinclinationofitssuccessivebeachesbecomechanged。 (FIGURE11。DIAGRAMOFABAYINADISTRICTWHICHHASBEGUNSLOWLYRISING) Ifitwerepossibletotraceanyoneofthemanybeach-lines，composingeachslopingterrace，itwouldofcoursebehorizontal;buttheonlylinesofdemarcationarethesummitandbasaledgesoftheescarpments。Nowthesummit-edgeofoneoftheseescarpmentsmarksthefurthestlineorpointtowhichtheseahascutintoamassofgravelslopingseaward;andastheseawillgenerallyhavegreaterpoweratthemouththanattheprotectedheadofthebay，sowilltheescarpmentatthemouthbecutdeeperintotheland，anditssummit-edgebehigher;consequentlyitwillnotbehorizontal。Withrespecttothebasalorloweredgesoftheescarpments，frompicturinginone’smindancientbaysENTIRELYsurroundedatsuccessiveperiodsbycliff-formedshores，one’sfirstimpressionisthattheyatleastnecessarilymustbehorizontal，iftheelevationhasbeenhorizontal。 Buthereisafallacy：foraftertheseahas，duringacessationoftheelevation，worncliffsallroundtheshoresofabay，whenthemovementrecommences，andespeciallyifitrecommencesslowly，itmightwellhappenthat，attheexposedmouthofthebay，thewavesmightcontinueforsometimewearingintotheland，whilstintheprotectedandupperpartssuccessivebeach-linesmightbeaccumulatinginaslopingsurfaceorterraceatthefootofthecliffswhichhadbeenlatelyreached：hence，supposingthewholelineofescarpmenttobefinallyupliftedabovethereachofthesea，itsbasallineorfootnearthemouthwillrunatalowerlevelthanintheupperandprotectedpartsofthebay;consequentlythisbasallinewillnotbehorizontal。Andithasalreadybeenshownthatthesummit-edgesofeachescarpmentwillgenerallybehighernearthemouth(fromtheseawardslopinglandbeingtheremostexposedandcutinto)thanneartheheadofthebay;thereforethetotalheightoftheescarpmentswillbegreatestnearthemouth;andfurtheruptheoldbayorvalleytheywillonbothsidesgenerallythinoutanddieaway：IhaveobservedthisthinningoutofthesuccessiveescarpmentatotherplacesbesidesCoquimbo; andforalongtimeIwasquiteunabletounderstanditsmeaning。TherudediagraminFigure11willperhapsrenderwhatImeanmoreintelligible;itrepresentsabayinadistrictwhichhasbegunslowlyrising。Beforethemovementcommenced，itissupposedthatthewaveshadbeenenabledtoeatintothelandandformcliffs，asfarup，butwithgraduallydiminishingpower，asthepointsAA：afterthemovementhadcommencedandgoneonforalittletime，theseaissupposedstilltohaveretainedthepower，attheexposedmouthofthebay，ofcuttingdownandintothelandasitslowlyemerged;butintheupperpartsofthebayitissupposedsoontohavelostthispower，owingtothemoreprotectedsituationandtothequantityofdetritusbroughtdownbytheriver;consequentlylowlandwasthereaccumulated。Asthislowlandwasformedduringaslowelevatorymovement，itssurfacewillgentlyslopeupwardsfromthebeachonallsides。Now，letusimaginethebay，nottomakethediagrammorecomplicated，suddenlyconvertedintoavalley：thebasallineofthecliffswillofcoursebehorizontal，asfarasthebeachisnowseenextendinginthediagram;butintheupperpartofthevalley，thislinewillbehigher，thelevelofthedistricthavingbeenraisedwhilstthelowlandwasaccumulatingatthefootoftheinlandcliffs。If，insteadofthebayinthediagrambeingsuddenlyconvertedintoavalley，wesupposewithmuchmoreprobabilityittobeupraisedslowly，thenthewavesintheupperpartsofthebaywillcontinueverygraduallytofailtoreachthecliffs，whicharenowinthediagramrepresentedaswashedbythesea，andwhich，consequently，willbeleftstandinghigherandhigheraboveitslevel;whilstatthestillexposedmouth，itmightwellhappenthatthewavesmightbeenabledtocutdeeperanddeeper，bothdownandintothecliffs，asthelandslowlyrose。 Thegreaterorlesserdestroyingpowerofthewavesatthemouthsofsuccessivebays，comparativelywiththissamepowerintheirupperandprotectedparts，willvaryasthebaysbecomechangedinformandsize，andthereforeatdifferentlevels，attheirmouthsandheads，moreorlessofthesurfacesbetweentheescarpments(thatis，theaccumulatedbeach-linesorterraces)willbeleftundestroyed：fromwhathasgonebeforewecanseethat，accordingastheelevatorymovementsaftereachcessationrecommencemoreorlessslowly，accordingtotheamountofdetritusdeliveredbytheriverattheheadsofthesuccessivebays，andaccordingtothedegreeofprotectionaffordedbytheiralteredforms，sowillagreaterorlessextentofterracebeaccumulatedintheupperpart，towhichtherewillbenosurfaceatacorrespondinglevelatthemouth：hencewecanperceivewhynooneterrace，takeninitswholebreadthandfollowedupthevalley，ishorizontal，thougheachseparatebeach-linemusthavebeenso;andwhytheinclinationoftheseveralterraces，bothtransversely，andlongitudinallyupthevalley，isnotalike。 Ihaveenteredintothiscaseinsomedetail，forIwaslongperplexed(andothershavefeltthesamedifficulty)inunderstandinghow，ontheideaofanequableelevationwiththeseaatintervalseatingintotheland，itcamethatneithertheterracesnortheuppernorloweredgesoftheescarpmentswerehorizontal。Alonglinesofcoast，evenofgreatlengths，suchasthatofPatagonia，iftheyarenearlyuniformlyexposed，thecorrodingpowerofthewaveswillbecheckedandconqueredbytheelevatorymovement，asoftenasitrecommences，ataboutthesameperiod;andhencetheterraces，oraccumulatedbeach-lines，willcommencebeingformedatnearlythesamelevels：ateachsucceedingperiodofrest，theywill，also，beeatenintoatnearlythesamerate，andconsequentlytherewillbeamuchclosercoincidenceintheirlevelsandinclinations，thanintheterracesandescarpmentsformedroundbayswiththeirdifferentpartsverydifferentlyexposedtotheactionofthesea。Itisonlywherethewavesareenabled，afteralonglapseoftime，slowlytocorrodehardrocks，ortothrowup，owingtothesupplyofsedimentbeingsmallandtothesurfacebeingsteeplyinclined，anarrowbeachormound，thatwecanexpect，asatGlenRoyinScotland(“PhilosophicalTransactions“1839page39。)，adistinctlinemarkinganoldsea-level，andwhichwillbestrictlyhorizontal，ifthesubsequentelevatorymovementshavebeenso：forinthesecasesnodiscernibleeffectswillbeproduced，exceptduringthelonginterveningperiodsofrest;whereasinthecaseofstep-formedcoasts，suchasthosedescribedinthisandtheprecedingchapter，theterracesthemselvesareaccumulatedduringtheslowelevatoryprocess，theaccumulationcommencingsoonerinprotectedthaninexposedsituations，andsoonerwherethereiscopioussupplyofdetritusthanwherethereislittle;ontheotherhand，thestepsorescarpmentsareformedduringthestationaryperiods，andaremoredeeplycutdownandintothecoast-landinexposedthaninprotectedsituations;——thecuttingaction，moreover，beingprolongedinthemostexposedparts，bothduringthebeginningandending，ifslow，oftheupwardmovement。 AlthoughintheforegoingdiscussionIhaveassumedtheelevationtohavebeenhorizontal，itmaybesuspected，fromtheconsiderableseawardslopeoftheterraces，bothupthevalleyofS。CruzandupthatofCoquimbo，thattherisinghasbeengreaterinlandthannearerthecoast。Thereisreasontobelieve(Mr。Placeinthe“QuarterlyJournalofScience“1824 volume17page42。)，fromtheeffectsproducedonthewater-courseofamillduringtheearthquakeof1822inChile，thattheupheavalonemileinlandwasnearlydouble，namely，betweenfiveandsevenfeet，towhatitwasonthePacific。Weknow，also，fromtheadmirableresearchesofM。 Bravais，thatinScandinaviatheancientsea-beachesgentlyslopefromtheinteriormountain-rangestowardsthecoast，andthattheyarenotparallelonetotheother(“VoyagesdelaComm。duNord“etc。also“ComptesRendus“ October1842。)，showingthattheproportionaldifferenceintheamountofelevationonthecoastandintheinterior，variedatdifferentperiods。 COQUIMBOTOGUASCO。 Inthisdistanceofninetymiles，Ifoundinalmosteverypartmarineshellsuptoaheightofapparentlyfromtwohundredtothreehundredfeet。 ThedesertplainnearChorosisthuscovered;itisboundedbytheescarpmentofahigherplain，consistingofpale-coloured，earthy，calcareousstone，likethatofCoquimbo，withthesamerecentshellsembeddedinit。InthevalleyofChaneral，asimilarbedoccursinwhich，differentlyfromthatofCoquimbo，IobservedmanyshellsoftheConcholepas：nearGuascothesamecalcareousbedislikewisemetwith。 InthevalleyofGuasco，thestep-formedterracesofgravelaredisplacedinamorestrikingmannerthanatanyotherpoint。Ifollowedthevalleyforthirty-sevenmiles(asreckonedbytheinhabitants)fromthecoasttoBallenar;innearlythewholeofthisdistance，fivegrandterraces，runningatcorrespondingheightsonbothsidesofthebroadvalley，aremoreconspicuousthanthethreebest-developedonesatCoquimbo。Theygivetothelandscapethemostsingularandformalaspect;andwhenthecloudshunglow，hidingtheneighbouringmountains，thevalleyresembledinthemoststrikingmannerthatofSantaCruz。Thewholethicknessoftheseterracesorplainsseemscomposedofgravel，ratherfirmlyaggregatedtogether，withoccasionalpartingseamsofclay：thepebblesontheupperplainareoftenwhitewashedwithanaluminoussubstance，asinPatagonia。 NearthecoastIobservedmanysea-shellsonthelowerplains。AtFreyrina(twelvemilesupthevalley)，therearesixterracesbesidethebottom- surfaceofthevalley：thetwoloweronesarehereonlyfromtwohundredtothreehundredyardsinwidth，buthigherupthevalleytheyexpandintoplains;thethirdterraceisgenerallynarrow;thefourthIsawonlyinoneplace，butthereitwasdistinctforthelengthofamile;thefifthisverybroad;thesixthisthesummit-plain，whichexpandsinlandintoagreatbasin。Nothavingabarometerwithme，Ididnotascertaintheheightoftheseplains，buttheyappearedconsiderablyhigherthanthoseatCoquimbo。Theirwidthvariesmuch，sometimesbeingverybroad，andsometimescontractingintomerefringesofseparateflat-toppedprojections，andthenquitedisappearing：attheonespot，wherethefourthterracewasvisible，thewholesixterraceswerecutoffforashortspacebyonesingleboldescarpment。NearBallenar(thirty-sevenmilesfromthemouthoftheriver)，thevalleybetweenthesummit-edgesofthehighestescarpmentsisseveralmilesinwidth，andthefiveterracesonbothsidesarebroadlydeveloped：thehighestcannotbelessthansixhundredfeetabovethebedoftheriver，whichitselfmust，Iconceive，besomehundredfeetabovethesea。 AnorthandsouthsectionacrossthevalleyinthispartisrepresentedinFigure12。 (FIGURE12。NORTHANDSOUTHSECTIONACROSSTHEVALLEYOFGUASCO，ANDOFA PLAINNORTHOFIT。 >Fromleft(north，high)toright(south，high)throughplainsBandAandtheRiverofGuascoattheTownofBallenar。) Onthenorthernsideofthevalleythesummit-plainofgravel，A，hastwoescarpments，onefacingthevalley，andtheotheragreatbasin-likeplain，B，whichstretchesforseveralleaguesnorthward。Thisnarrowplain，A，withthedoubleescarpment，evidentlyonceformedaspitorpromontoryofgravel，projectingintoanddividingtwogreatbays，andsubsequentlywaswornonbothsidesintosteepcliffs。WhethertheseveralescarpmentsinthisvalleywereformedduringthesamestationaryperiodswiththoseofCoquimbo，Iwillnotpretendtoconjecture;butifsotheinterveningandsubsequentelevatorymovementsmusthavebeenheremuchmoreenergetic，fortheseplainscertainlystandatamuchhigherlevelthandothoseofCoquimbo。 COPIAPO。 >FromGuascotoCopiapo，IfollowedtheroadnearthefootoftheCordillera，andthereforesawnoupraisedremains。Atthemouth，however，ofthevalleyofCopiapothereisaplain，estimatedbyMeyen(“ReiseumdieErde“th。1s。372etseq。)betweenfiftyandseventyfeetinheight，ofwhichtheupperpartconsistschieflyofgravel，aboundingwithrecentshells，chieflyoftheConcholepas，VenusDombeyi，andCalyptraeatrochiformis。Alittleinland，onaplainestimatedbymyselfatnearlythreehundredfeet，theupperstratumwasformedofbrokenshellsandsandcementedbywhitecalcareousmatter，andaboundingwithembeddedrecentshells，ofwhichtheMuliniaByronensisandPectenpurpuratuswerethemostnumerous。Thelowerplainstretchesforsomemilessouthward，andforanunknowndistancenorthward，butnotfarupthevalley;itsseawardface，accordingtoMeyen，iswornintocavesabovethelevelofthepresentbeach。ThevalleyofCopiapoismuchlesssteeplyinclinedandlessdirectinitscoursethananyothervalleywhichIsawinChile;anditsbottomdoesnotgenerallyconsistofgravel：therearenostep-formedterracesinit，exceptatonespotnearthemouthofthegreatlateralvalleyoftheDespobladowherethereareonlytwo，oneabovetheother：lowerdownthevalley，inoneplaceIobservedthatthesolidrockhadbeencutintotheshapeofabeach，andwassmoothedoverwithshingle。 NorthwardofCopiapo，inlatitude26degreesS。theoldvoyagerWaferfoundimmensenumbersofsea-shellssomemilesfromthecoast。(Burnett’s“CollectionofVoyages“volume4page193。)AtCobija(latitude22degrees34’)M。d’Orbignyobservedbedsofgravelandbrokenshells，containingtenspeciesofrecentshells;healsofound，onprojectingpointsofporphyry，ataheightof300feet，shellsofConcholepas，Chiton，Calyptraea，Fissurella，andPatella，stillattachedtothespotsonwhichtheyhadlived。M。d’Orbignyarguesfromthisfact，thattheelevationmusthavebeengreatandsudden(“Voyage，PartGeolog。”page94。M。d’Orbigny(page98)，insummingup，says：“S’ilestcertain(ashebelieves)quetouslesterrainsenpente，comprisentrelameretlesmontagnessontl’ancienrivagedelamer，ondoitsupposer，pourl’ensemble，unexhaussementqueceneseraitpasmoindrededeuxcentmetres;ilfaudraitsupposerencorequecesoulevementn’apointetegraduel;……maisqu’ilresulteraitd’uneseuleetmemecausefortuite，“etc。Now，onthisview，whentheseawasformingthebeachatthefootofthemountains，manyshellsofConcholepas，Chiton，Calyptraea，Fissurella，andPatella(whichareknowntoliveclosetothebeach)，wereattachedtorocksatadepthof300feet，andatadepthof600feetseveralofthesesameshellswereaccumulatingingreatnumbersinhorizontalbeds。FromwhatIhavemyselfseenindredging，Ibelievethistobeimprobableinthehighestdegree，ifnotimpossible;andIthinkeveryonewhohasreadProfessorE。Forbes’sexcellentresearchesonthesubject，willwithouthesitationagreeinthisconclusion。)：tomeitappearsfarmoreprobablethatthemovementwasgradual，withsmallstartsasduringtheearthquakesof1822and1835，bywhichwholebedsofshellsattachedtotherockswereliftedabovethesubsequentreachofthewaves。 M。d’Orbignyalsofoundrolledpebblesextendingupthemountaintoaheightofatleastsixhundredfeet。AtIquique(latitude20degrees12’ S。)，inagreataccumulationofsand，ataheightestimatedbetweenonehundredandfiftyandtwohundredfeet，Iobservedmanylargesea-shellswhichIthoughtcouldnothavebeenblownupbythewindtothatheight。 Mr。J。H。Blakehaslatelydescribedtheseshells：hestatesthat“inlandtowardthemountainstheyformacompactuniformbed，scarcelyatraceoftheoriginalshellsbeingdiscernible;butasweapproachtheshore，theformsbecomegraduallymoredistincttillwemeetwiththelivingshellsonthecoast。”(“Silliman’sAmericanJournalofScience“volume44page2。) Thisinterestingobservation，showingbythegradualdecayoftheshellshowslowlyandgraduallythecoastmusthavebeenuplifted，weshallpresentlyseefullyconfirmedatLima。AtArica(latitude18degrees28’)，M。d’Orbignyfoundagreatrangeofsand-dunes，fourteenleaguesinlength，stretchingtowardsTacna，includingrecentshellsandbonesofCetacea，andreachinguptoaheightof300feetabovethesea。(“Voyage“etc。page101。)LieutenantFreyerhasgivensomemoreprecisefacts：hestates(InalettertoMr。Lyell“GeologicalProceedings“volume2page179。)thattheMorroofAricaisaboutfourhundredfeethigh;itiswornintoobscureterraces，onthebarerockofwhichhefoundBaliniandMilleporaeadhering。Attheheightofbetweentwentyandthirtyfeettheshellsandcoralswereinaquitefreshstate，butatfiftyfeettheyweremuchabraded;therewere，however，tracesoforganicremainsatgreaterheights。 OntheroadfromTacnatoArequipa，betweenLoquimboandMoquegua，Mr。M。 Hamiltonfoundnumerousrecentseashellsinsand，ataconsiderabledistancefromthesea。(“EdinburghNewPhilosophicalJournal“volume30 page155。) LIMA。 NorthwardofArica，Iknownothingofthecoastforaboutaspaceoffivedegreesoflatitude;butnearCallao，theportofLima，thereisabundantandverycuriousevidenceoftheelevationoftheland。TheislandofSanLorenzoisupwardsofonethousandfeethigh;thebassetedgesofthestratacomposingthelowerpartarewornintothreeobscure，narrow，slopingstepsorledges，whichcanbeseenonlywhenstandingonthem：theyprobablyresemblethosedescribedbyLieutenantFreyeratArica。Thesurfaceofthelowerledge，whichextendsfromalowcliffoverhangingtheseatothefootofthenextupperescarpment，iscoveredbyanenormousaccumulationofrecentshells。(M。Chevalier，inthe“Voyageofthe’Bonite’“observedtheseshells;buthisspecimenswerelost——“L’Institut“ 1838page151。)Thebedislevel，andinsomepartsmorethantwofeetinthickness;Itraceditoveraspaceofonemileinlength，andheardofitinotherplaces：theuppermostpartiseighty-fivefeetbythebarometerabovehigh-watermark。Theshellsarepackedtogether，butnotstratified： theyaremingledwithearthandstones，andaregenerallycoveredbyafewinchesofdetritus;theyrestonamassofnearlyangularfragmentsoftheunderlyingsandstone，sometimescementedtogetherbycommonsalt。I collectedeighteenspeciesofshellsofallagesandsizes。Severaloftheunivalveshadevidentlylonglaindeadatthebottomofthesea，fortheirINSIDESwereincrustedwithBalaniandSerpulae。All，accordingtoMr。G。B。 Sowerby，arerecentspecies：theyconsistof：—— 1。MytilusMagellanicus：sameasthatfoundatValparaiso，andtherestatedtobeprobablydistinctfromthetrueM。Magellanicusoftheeastcoast。 2。Venuscostellata，Sowerby“ZoologicalProceedings。” 3。Pectenpurpuratus，Lam。 4。Chama，probablyechinulata，Brod。 5。CalyptraeaByronensis，Gray。 6。Calyptraearadians(Trochus，Lam。) 7。Fissurellaaffinis，Gray。 8。Fissurellabiradiata，Trembly。 9。Purpurachocolatta，Duclos。 10。PurpuraPeruviana，Gray。 11。Purpuralabiata，Gray。 12。Purpurabuxea(Murex，Brod。)。 13。ConcholepasPeruviana。 14。Nassa，relatedtoreticulata。 15。Tritonrudis，Brod。 16。Trochus，notyetdescribed，butwell-knownandverycommon。 17and18。Balanus，twospecies，bothcommononthecoast。 Theseupraisedshellsappeartobenearlyinthesameproportionalnumbers—— withtheexceptionoftheCrepidulaebeingmorenumerous——withthoseontheexistingbeach。Thestateofpreservationofthedifferentspeciesdifferedmuch;butmostofthemweremuchcorroded，brittle，andbleached： theupperandlowersurfacesoftheConcholepashadgenerallyquitescaledoff：someoftheTrochiandFissurellaestillpartiallyretaintheircolours。Itisremarkablethattheseshells，takenalltogether，havefullyasancientanappearance，althoughtheextremelyaridclimateappearshighlyfavourablefortheirpreservation，asthosefrom1，300feetatValparaiso，andcertainlyamoreancientappearancethanthosefromfivetosixhundredfeetfromValparaisoandConcepcion;atwhichplacesIhaveseengrassandothervegetablesactuallygrowingoutoftheshells。ManyoftheunivalveshereatSanLorenzowerefilledwith，andunitedtogetherby，puresalt，probablyleftbytheevaporationofthesea-spray，asthelandslowlyemerged。(Theunderlyingsandstonecontainstruelayersofsalt;sothatthesaltmaypossiblyhavecomefromthebedsinthehigherpartsoftheisland;butIthinkmoreprobablyfromthesea-spray。ItisgenerallyassertedthatrainneverfallsonthecoastofPeru;butthisisnotquiteaccurate;for，onseveraldays，duringourvisit，theso-calledPeruviandewfellinsufficientquantitytomakethestreetsmuddy，anditwouldcertainlyhavewashedsodeliquescentasubstanceassaltintothesoil。I statethisbecauseM。d’Orbigny，indiscussingananalogoussubject，supposesthatIhadforgottenthatitneverrainsonthiswholelineofcoast。SeeUlloa’s“Voyage“volume2EnglishTranslationpage67foranaccountofthemuddystreetsofLima，andonthecontinuanceofthemistsduringthewholewinter。Rain，also，fallsatrareintervalseveninthedriestdistricts，as，forinstance，duringfortydays，in1726，atChocope(7degrees46’);thisrainentirelyruined(“Ulloa“etc。page18)themudhousesoftheinhabitants。)Onthehighestpartsoftheledge，smallfragmentsoftheshellsweremingledwith，andevidentlyinprocessofreductioninto，ayellowish-white，soft，calcareouspowder，tastingstronglyofsalt，andinsomeplacesasfineaspreparedmedicinalchalk。 FOSSIL-REMAINSOFHUMANART。 InthemidstoftheseshellsonSanLorenzo，Ifoundlightcorallines，thehornyovule-casesofMollusca，rootsofseaweed(Mr。SmithofJordanHillfoundpiecesofseaweedinanupraisedpleistocenedepositinScotland。SeehisadmirablePaperinthe“EdinburghNewPhilosophicalJournal“volume25 page384。)，bonesofbirds，theheadsofIndiancornandothervegetablematter，apieceofwovenrushes，andanotherofnearlydecayedCOTTON string。Iextractedtheseremainsbydiggingahole，onalevelspot;andtheyhadallindisputablybeenembeddedwiththeshells。Icomparedtheplaitedrush，theCOTTONstring，andIndiancorn，atthehouseofanantiquary，withsimilarobjects，takenfromtheHuacasorburial-groundsoftheancientPeruvians，andtheywereundistinguishable;itshouldbeobservedthatthePeruviansusedstringonlyofcotton。Thesmallquantityofsandorgravelwiththeshells，theabsenceoflargestones，thewidthandthicknessofthebed，andthetimerequisiteforaledgetobecutintothesandstone，allshowthattheseremainswerenotthrownhighupbyanearthquake-wave：ontheotherhand，thesefacts，togetherwiththenumberofdeadshells，andoffloatingobjects，bothmarineandterrestrial，bothnaturalandhuman，renderitalmostcertainthattheywereaccumulatedonatruebeach，sinceupraisedeighty-fivefeet，andupraisedthismuchsinceINDIANMANINHABITEDPERU。Theelevationmayhavebeen，eitherbyseveralsmallsuddenstarts，orquitegradual;inthislattercasetheunrolledshellshavingbeenthrownupduringgalesbeyondthereachofthewaveswhichafterwardsbrokeontheslowlyemergingland。Ihavemadetheseremarks，chieflybecauseIwasatfirstsurprisedatthecompletedifferenceinnature，betweenthisbroad，smooth，upraisedbedofshells，andthepresentshingle-beachatthefootofthelowsandstone-cliffs;butabeachformed，whentheseaiscuttingintotheland，asisshownnowtobethecasebythelowbaresandstone-cliffs，oughtnottobecomparedwithabeachaccumulatedonagentlyinclinedrockysurface，ataperiodwhenthesea(probablyowingtotheelevatorymovementinprocess)wasnotabletoeatintotheland。Withrespecttothemassofnearlyangular，salt- cementedfragmentsofsandstone，whichlieundertheshells，andwhicharesounlikethematerialsofanordinarysea-beach;Ithinkitprobableafterhavingseentheremarkableeffectsoftheearthquakeof1835(Ihavedescribedthisinmy“JournalofResearches“page3032ndedition。)，inabsolutelyshatteringasifbygunpowdertheSURFACEoftheprimaryrocksnearConcepcion，thatasmoothbaresurfaceofstonewasleftbytheseacoveredbytheshellymass，andthatafterwardswhenupraised，itwassuperficiallyshatteredbythesevereshockssooftenexperiencedhere。 TheverylowlandsurroundingthetownofCallao，istothesouthjoinedbyanobscureescarpmenttoahigherplain(southofBellaVista)，whichstretchesalongthecoastforalengthofabouteightmiles。Thisplainappearstotheeyequitelevel;butthesea-cliffsshowthatitsheightvaries(asfarasIcouldestimate)fromseventytoonehundredandtwentyfeet。Itiscomposedofthin，sometimeswaving，bedsofclay，oftenofbrightredandyellowcolours，oflayersofimpuresand，andinonepartwithagreatstratifiedmassofgraniticpebbles。Thesebedsarecappedbyaremarkablemass，varyingfromtwotosixfeetinthickness，ofreddishloamormud，containingmanyscatteredandbrokenfragmentsofrecentmarineshells，sometimesthoughrarelysinglelargeroundpebble，morefrequentlyshortirregularlayersoffinegravel，andverymanypiecesofredcoarseearthenware，whichfromtheircurvaturesmustoncehaveformedpartsoflargevessels。TheearthenwareisofIndianmanufacture;andI foundexactlysimilarpiecesaccidentallyincludedwithinthebricks，ofwhichtheneighbouringancientPeruvianburial-moundsarebuilt。Thesefragmentsaboundedinsuchnumbersincertainspots，thatitappearedasifwaggon-loadsofearthenwarehadbeensmashedtopieces。Thebrokensea- shellsandpotteryarestrewedbothonthesurface，andthroughoutthewholethicknessofthisupperloamymass。IfoundthemwhereverIexaminedthecliffs，foraspaceofbetweentwoandthreemiles，andforhalfamileinland;andtherecanbelittledoubtthatthissamebedextendswithasmoothsurfaceseveralmilesfurtherovertheentireplain。Besidesthelittleincludedirregularlayersofsmallpebbles，thereareoccasionallyveryobscuretracesofstratification。 Atoneofthehighestpartsofthecliff，estimated120feetabovethesea，wherealittleravinecamedown，thereweretwosections，atrightanglestoeachother，ofthefloorofashedorbuilding。Inbothsectionsorfaces，tworows，oneovertheother，oflargeroundstonescouldbedistinctlyseen;theywerepackedclosetogetheronanartificiallayerofsandtwoinchesthick，whichhadbeenplacedonthenaturalclay-beds;theroundstoneswerecoveredbythreefeetinthicknessoftheloamwithbrokensea-shellsandpottery。Hence，beforethiswidelyspread-outbedofloamwasdeposited，itiscertainthattheplainwasinhabited;anditisprobable，fromthebrokenvesselsbeingsomuchmoreabundantincertainspotsthaninothers，andfromtheunderlyingclaybeingfittedfortheirmanufacture，thatthekilnsstoodhere。 Thesmoothnessandwideextentoftheplain，thebulkofmatterdeposited，andtheobscuretracesofstratificationseemtoindicatethattheloamwasdepositedunderwater;ontheotherhand，thepresenceofsea-shells，theirbrokenstate，thepebblesofvarioussizes，andtheartificialfloorofroundstones，almostprovethatitmusthaveoriginatedinarushofwaterfromtheseaovertheland。Theheightoftheplain，namely，120feet，rendersitimprobablethatanearthquake-wave，vastassomehaveherebeen，couldhavebrokenoverthesurfaceatitspresentlevel;butwhenthelandstoodeighty-fivefeetlower，attheperiodwhentheshellswerethrownupontheledgeatS。Lorenzo，andwhenasweknowmaninhabitedthisdistrict，suchaneventmightwellhaveoccurred;andifwemayfurthersuppose，thattheplainwasatthattimeconvertedintoatemporarylake，asactuallyoccurred，duringtheearthquakesof1713and1746，inthecaseofthelowlandroundCallaoowingtoitsbeingencircledbyahighshingle-beach，alltheappearancesabovedescribedwillbeperfectlyexplained。Imustadd，thatatalowerlevelnearthepointwherethepresentlowlandroundCallaojoinsthehigherplain，thereareappearancesoftwodistinctdepositsbothapparentlyformedbydebacles：intheupperone，ahorse’stoothandadog’sjawwereembedded;sothatbothmusthavebeenformedafterthesettlementoftheSpaniards：accordingtoAcosta，theearthquake-waveof1586roseeighty-fourfeet。 TheinhabitantsofCallaodonotbelieve，asfarasIcouldascertain，thatanychangeinlevelisnowinprogress。Thegreatfragmentsofbrickwork，whichitisassertedcanbeseenatthebottomofthesea，andwhichhavebeenadducedasaproofofalatesubsidence，are，asIaminformedbyMr。 Gill，aresidentengineer，loosefragments;thisisprobable，forIfoundonthebeach，andnotneartheremainsofanybuilding，massesofbrickwork，threeandfourfeetsquare，whichhadbeenwashedintotheirpresentplaces，andsmoothedoverwithshingleduringtheearthquakeof1746。Thespitofland，onwhichtheruinsofOLDCallaostand，issoextremelylowandnarrow，thatitisimprobableinthehighestdegreethatatownshouldhavebeenfoundedonitinitspresentstate;andIhavelatelyheardthatM。Tschudihascometotheconclusion，fromacomparisonofoldwithmoderncharts，thatthecoastbothsouthandnorthofCallaohassubsided。(IamindebtedforthisfacttoDr。E。Dieffenbach。Imayaddthatthereisatradition，thattheislandsofSanLorenzoandFrontonwereoncejoined，andthatthechannelbetweenSanLorenzoandthemainland，nowabovetwomilesinwidth，wassonarrowthatcattleusedtoswimover。)I haveshownthattheislandofSanLorenzohasbeenupraisedeighty-fivefeetsincethePeruviansinhabitedthiscountry;andwhatevermayhavebeentheamountofrecentsubsidence，bysomuchmoremusttheelevationhaveexceededtheeighty-fivefeet。Inseveralplacesinthisneighbourhood，marksofsea-actionhavebeenobserved：UlloagivesadetailedaccountofsuchappearancesatapointfiveleaguesnorthwardofCallao：Mr。 CruikshankfoundnearLimasuccessivelinesofsea-cliffs，withroundedblocksattheirbases，ataheightof700feetabovethepresentlevelofthesea。(“ObservacionessobreelClimadelLima“parDr。H。Unanuepage4——Ulloa’s“Voyage“volume2EnglishTranslationpage97——ForMr。 Cruikshank’sobservations，seeMr。Lyell’s“PrinciplesofGeology“1steditionvolume3page130。) ONTHEDECAYOFUPRAISEDSEA-SHELLS。 IhavestatedthatmanyoftheshellsonthelowerinclinedledgeorterraceofSanLorenzoarecorrodedinapeculiarmanner，andthattheyhaveamuchmoreancientappearancethanthesamespeciesatconsiderablygreaterheightsonthecoastofChile。Ihave，also，statedthattheseshellsintheupperpartoftheledge，attheheightofeighty-fivefeetabovethesea，arefalling，andinsomepartsarequitechangedintoafine，soft，saline，calcareouspowder。Thefinestpartofthispowderhasbeenanalysedforme，attherequestofSirH。DelaBeche，bythekindnessofMr。TrenhamReeksoftheMuseumofEconomicGeology;itconsistsofcarbonateoflimeinabundance，ofsulphateandmuriateoflime，andofmuriateandsulphateofsoda。Thecarbonateoflimeisobviouslyderivedfromtheshells;andcommonsaltissoabundantinpartsofthebed，that，asbeforeremarked，theunivalvesareoftenfilledwithit。Thesulphateoflimemayhavebeenderived，ashasprobablythecommonsalt，fromtheevaporationofthesea-spray，duringtheemergenceoftheland;forsulphateoflimeisnowcopiouslydepositedfromthesprayontheshoresofAscension。(See“VolcanicIslands“etc。bytheAuthor。)Theothersalinebodiesmayperhapshavebeenpartiallythusderived，butchiefly，asI concludefromthefollowingfacts，throughadifferentmeans。 Onmostpartsofthesecondledgeoroldsea-beach，ataheightof170 feet，thereisalayerofwhitepowderofvariablethickness，asmuchinsomepartsastwoinches，lyingontheangular，salt-cementedfragmentsofsandstoneandunderaboutfourinchesofearth，whichpowder，fromitscloseresemblanceinnaturetotheupperandmostdecayedpartsoftheshellymass，Icanhardlydoubtoriginallyexistedasabedofshells，nowmuchcollapsedandquitedisintegrated。Icouldnotdiscoverwiththemicroscopeatraceoforganicstructureinit;butitschemicalconstituents，accordingtoMr。Reeks，arethesameasinthepowderextractedfromamongstthedecayingshellsonthelowerledge，withthemarkedexceptionthatthecarbonateoflimeispresentinonlyverysmallquantity。Onthethirdandhighestledge，Iobservedsomeofthispowderinasimilarposition，andlikewiseoccasionallyinsmallpatchesatconsiderablygreaterheightsnearthesummitoftheisland。AtIquique，wherethewholefaceofthecountryiscoveredbyahighlysaliferousalluvium，andwheretheclimateisextremelydry，wehaveseenthat，accordingtoMr。Blake，theshellswhichareperfectnearthebeachbecome，inascending，graduallylessandlessperfect，untilscarcelyatraceoftheiroriginalstructurecanbediscovered。Itisknownthatcarbonateoflimeandcommonsaltleftinamasstogether，andslightlymoistened，partiallydecomposeeachother(IaminformedbyDr。Kane，throughMr。 Reeks，thatamanufactorywasestablishedonthisprincipleinFrance，butfailedfromthesmallquantityofcarbonateofsodaproduced。Sprengel“Gardeners’Chronicle“1845page157，states，thatsaltandcarbonateoflimeareliabletomutualdecompositioninthesoil。SirH。DelaBecheinformsme，thatcalcareousrockswashedbythesprayofthesea，areoftencorrodedinapeculiarmanner;seealsoonthislattersubject“Gardeners’ Chronicle“page6751844。)：nowwehaveatSanLorenzoandatIquique，intheshellsandsaltpackedtogether，andoccasionallymoistenedbytheso- calledPeruviandew，theproperelementsforthisaction。WecanthusunderstandthepeculiarcorrodedappearanceoftheshellsonSanLorenzo，andthegreatdecreaseofquantityinthecarbonateoflimeinthepowderontheupperledge。Thereis，however，agreatdifficultyonthisview，fortheresultantsaltsshouldbecarbonateofsodaandmuriateoflime;thelatterispresent，butnotthecarbonateofsoda。HenceIamledtotheperhapsunauthorisedconjecture(whichIshallhereafterhavetoreferto) thatthecarbonateofsoda，bysomeunexplainedmeans，becomesconvertedintoasulphate。 Iftheaboveremarksbejust，weareledtotheveryunexpectedconclusion，thatadryclimate，byleavingthesaltfromthesea-sprayundissolved，ismuchlessfavourabletothepreservationofupraisedshellsthanahumidclimate。Howeverthismaybe，itisinterestingtoknowthemannerinwhichmassesofshells，graduallyupraisedabovethesea-level，decayandfinallydisappear。 SUMMARYONTHERECENTELEVATIONOFTHEWESTCOASTOFSOUTHAMERICA。 Wehaveseenthatupraisedmarineremainsoccuratintervals，andinsomepartsalmostcontinuously，fromlatitude45degrees35’to12degreesS。alongtheshoresofthePacific。Thisisadistance，inanorthandsouthline，of2，075geographicalmiles。FromByron’sobservations，theelevationhasnodoubtextendedsixtymilesfurthersouth;andfromthesimilarityintheformofthecountrynearLima，ithasprobablyextendedmanyleaguesfurthernorth。(ImaytakethisopportunityofstatingthatinaMS。intheGeologicalSocietybyMr。Weaver，itisstatedthatbedsofoystersandotherrecentshellsarefoundthirtyfeetabovethelevelofthesea，inmanypartsofTampico，intheGulfofMexico。)Alongthisgreatlineofcoast，besidestheorganicremains，thereareinverymanyparts，marksoferosion，caves，ancientbeaches，sand-dunes，andsuccessiveterracesofgravel，allabovethepresentlevelofthesea。Fromthesteepnessofthelandonthissideofthecontinent，shellshaverarelybeenfoundatgreaterdistancesinlandthanfromtwotothreeleagues;butthemarksofsea-actionareevidentfartherfromthecoast;forinstance，inthevalleyofGuasco，atadistanceofbetweenthirtyandfortymiles。Judgingfromtheupraisedshellsalone，theelevationinChiloehasbeen350feet，atConcepcioncertainly625feet;andbyestimation1，000feet;atValparaiso1，300feet;atCoquimbo252feet;northwardofthisplace，sea-shellshavenot，Ibelieve，beenfoundabove300feet;andatLimatheywerefallingintodecay(hastenedprobablybythesalt)at85feet。NotonlyhasthisamountofelevationtakenplacewithintheperiodofexistingMolluscaandCirripedes;buttheirproportionalnumbersintheneighbouringseahaveinmostcasesremainedthesame。NearLima，however，asmallchangeinthisrespectbetweenthelivingandtheupraisedwasobserved：atCoquimbothiswasmoreevident，alltheshellsbeingexistingspecies，butwiththoseembeddedintheuppermostcalcareousplainnotapproximatingsocloselyinproportionalnumbers，asdothosethatlielooseonitssurfaceattheheightof252feet，andstilllesscloselythanthosewhicharestrewedonthelowerplains，whichlatterareidenticalinproportionalnumberswiththosenowcastuponthebeach。Fromthiscircumstance，andfromnotfinding，uponcarefulexamination，nearCoquimboanyshellsatagreaterheightthan252feet，IbelievethattherecentelevationtherehasbeenmuchlessthanatValparaiso，whereithasbeen1，300feet，andImayadd，thanatConcepcion。ThisconsiderableinequalityintheamountofelevationatCoquimboandValparaiso，placesonly200milesapart，isnotimprobable，considering，first，thedifferenceintheforceandnumberoftheshocksnowyearlyaffectingdifferentpartsofthiscoast;and，secondly，thefactofsingleareas，suchasthatoftheprovinceofConcepcion，havingbeenupliftedveryunequallyduringthesameearthquake。Itwould，inmostcases，beveryhazardoustoinferaninequalityofelevation，fromshellsbeingfoundonthesurfaceorinsuperficialbedsatdifferentheights;forwedonotknowonwhattheirrateofdecaydepends;andatCoquimbooneinstanceoutofmanyhasbeengiven，ofapromontory，which，fromtheoccurrenceofoneverysmallcollectionoflime-cementedshells，hasindisputablybeenelevated242feet，andyetonwhich，notevenafragmentofshellcouldbefoundoncarefulexaminationbetweenthisheightandthebeach，althoughmanysitesappearedveryfavourableforthepreservationoforganicremains：theabsence，also，ofshellsonthegravel-terracesashortdistanceupthevalleyofCoquimbo，thoughabundantonthecorrespondingterracesatitsmouth，shouldbeborneinmind。 Thereareotherepochs，besidesthatoftheexistenceofrecentMollusca，bywhichtojudgeofthechangesoflevelonthiscoast。AtLima，aswehavejustseen，theelevationhasbeenatleasteighty-fivefeet，withintheIndo-humanperiod;andsincethearrivaloftheSpaniardsin1530，therehasapparentlybeenasinkingofthesurface。AtValparaiso，inthecourseof220years，therisemusthavebeenlessthannineteenfeet;butithasbeenasmuchasfromtentoelevenfeetintheseventeenyearssubsequentlyto1817，andofthisriseonlyapartcanbeattributedtotheearthquakeof1822，theremainderhavingbeeninsensibleandapparentlystill，in1834，inprogress。AtChiloetheelevationhasbeengradual，andaboutfourfeetduringfouryears。AtCoquimbo，also，ithasbeengradual，andinthecourseof150yearshasamountedtoseveralfeet。Thesuddensmallupheavals，accompaniedbyearthquakes，asin1822atValparaiso，in1835atConcepcion，andin1837intheChonosArchipelago，arefamiliartomostgeologists，butthegradualrisingofthecoastofChilehasbeenhardlynoticed;itis，however，veryimportant，asconnectingtogetherthesetwoordersofevents。 TheriseofLima，havingbeeneighty-fivefeetwithintheperiodofman，isthemoresurprisingifwerefertotheeasterncoastofthecontinent，foratPortS。Julian，inPatagonia，thereisgoodevidence(asweshallhereaftersee)thatwhenthelandstoodninetyfeetlower，theMacrauchenia，amammiferousbeast，wasalive;andatBahiaBlanca，whenitstoodonlyafewfeetlowerthanitnowdoes，manygiganticquadrupedsrangedovertheadjoiningcountry。ButthecoastofPatagoniaissomewaydistantfromtheCordillera，andthemovementatBahiaBlancaisperhapsnowaysconnectedwiththisgreatrange，butratherwiththetertiaryvolcanicrocksofBandaOriental，andthereforetheelevationattheseplacesmayhavebeeninfinitelyslowerthanonthecoastofPeru。Allsuchspeculations，however，mustbevague，forasweknowwithcertaintythattheelevationofthewholecoastofPatagoniahasbeeninterruptedbymanyandlongpauses，whowillpretendtosaythat，insuchcases，manyandlongperiodsofsubsidencemaynotalsohavebeenintercalated？ InmanypartsofthecoastofChileandPerutherearemarksoftheactionoftheseaatsuccessiveheightsontheland，showingthattheelevationhasbeeninterruptedbyperiodsofcomparativerestintheupwardmovement，andofdenudationintheactionofthesea。TheseareplainestatChiloe，where，inaheightofaboutfivehundredfeet，therearethreeescarpments，——atCoquimbo，whereinaheightof364feet，therearefive，—— atGuasco，wheretherearesix，ofwhichfivemayperhapscorrespondwiththoseatCoquimbo，butifso，thesubsequentandinterveningelevatorymovementshavebeenheremuchmoreenergetic，——atLima，where，inaheightofabout250feettherearethreeterraces，andothers，asitisasserted，atconsiderablygreaterheights。Thealmostentireabsenceofancientmarksofsea-actionatdefinedlevelsalongconsiderablespacesofcoast，asnearValparaisoandConcepcion，ishighlyinstructive，forasitisimprobablethattheelevationattheseplacesaloneshouldhavebeencontinuous，wemustattributetheabsenceofsuchmarkstothenatureandformofthecoast-rocks。SeeingoverhowmanyhundredmilesofthecoastofPatagonia，andonhowmanyplacesontheshoresofthePacific，theelevatoryprocesshasbeeninterruptedbyperiodsofcomparativerest，wemayconclude，conjointlywiththeevidencedrawnfromotherquartersoftheworld，thattheelevationofthelandisgenerallyanintermittentaction。Fromthequantityofmatterremovedintheformationoftheescarpments，especiallyofthoseofPatagonia，itappearsthattheperiodsofrestinthemovement，andofdenudationoftheland，havegenerallybeenverylong。InPatagonia，wehaveseenthattheelevationhasbeenequable，andtheperiodsofdenudationsynchronousoververywidespacesofcoast;ontheshoresofthePacific，owingtotheterraceschieflyoccurringinthevalleys，wehavenotequalmeansofjudgingonthispoint;andtheverydifferentheightsoftheupraisedshellsatCoquimbo，Valparaiso，andConcepcionseemdirectlyopposedtosuchaconclusion。 Whetheronthissideofthecontinenttheelevation，betweentheperiodsofcomparativerestwhentheescarpmentswereformed，hasbeenbysmallsuddenstarts，suchasthoseaccompanyingrecentearthquakes，or，asismostprobable，bysuchstartsconjointlywithagradualupwardmovement，orbygreatandsuddenupheavals，Ihavenodirectevidence。Butasontheeasterncoast，Iwasledtothink，fromtheanalogyofthelasthundredfeetofelevationinLaPlata，andfromthenearlyequalsizeofthepebblesovertheentirewidthoftheterraces，andfromtheupraisedshellsbeingalllittoralspecies，thattheelevationhadbeengradual;sodoIonthiswesterncoast，fromtheanalogyofthemovementsnowinprogress，andfromthevastnumbersofshellsnowlivingexclusivelyonorclosetothebeach，whicharestrewedoverthewholesurfaceofthelanduptoveryconsiderableheights，conclude，thatthemovementherealsohasbeenslowandgradual，aidedprobablybysmalloccasionalstarts。WeknowatleastthatatCoquimbo，wherefiveescarpmentsoccurinaheightof364feet，thesuccessiveelevations，iftheyhavebeensudden，cannothavebeenverygreat。Ithas，Ithink，beenshownthattheoccasionalpreservationofshells，unrolledandunbroken，isnotimprobableevenduringaquitegradualrisingoftheland;andtheirpreservation，ifthemovementhasbeenaidedbysmallstarts，isquiteconformablewithwhatactuallytakesplaceduringrecentearthquakes。 Judgingfromthepresentactionofthesea，alongtheshoresofthePacific，onthedepositsofitsownaccumulation，thepresenttimeseemsinmostplacestobeoneofcomparativerestintheelevatorymovement，andofdenudationoftheland。UndoubtedlythisisthecasealongthewholegreatlengthofPatagonia。AtChiloe，however，wehaveseenthatanarrowslopingfringe，coveredwithvegetation，separatesthepresentsea-beachfromalineoflowcliffs，whichthewaveslatelyreached;here，then，thelandisgaininginbreadthandheight，andthepresentperiodisnotoneofrestintheelevationandofcontingentdenudation;butiftherisingbenotprolongedataquickrate，thereiseveryprobabilitythattheseawillsoonregainitsformerhorizontallimits。Iobservedsimilarlowslopingfringesonseveralpartsofthecoast，bothnorthwardofValparaisoandnearCoquimbo;butatthislatterplace，fromthechangeinformwhichthecoasthasundergonesincetheoldescarpmentswereworn，itmaybedoubtedwhetherthesea，actingforanylengthoftimeatitspresentlevel，wouldeatintotheland;foritnowrathertendstothrowupgreatmassesofsand。ItisfromfactssuchasthesethatIhavegenerallyusedthetermCOMPARATIVErest，asappliedtotheelevationoftheland;therestorcessationinthemovementbeingcomparativebothwithwhathasprecededitandfollowedit，andwiththesea’spowerofcorrosionateachspotandateachlevel。NearLima，thecliff-formedshoresofSanLorenzo，andonthemainlandsouthofCallao，showthattheseaisgainingontheland;andaswehaveheresomeevidencethatitssurfacehaslatelysubsidedorisstillsinking，theperiodsofcomparativerestintheelevationandofcontingentdenudation，mayprobablyinmanycasesincludeperiodsofsubsidence。Itisonly，aswasshownindetailwhendiscussingtheterracesofCoquimbo，whentheseawithdifficultyandafteralonglapseoftimehaseithercorrodedanarrowledgeintosolidrock，orhasheapeduponasteepsurfaceaNARROWmoundofdetritus，thatwecanconfidentlyassertthatthelandatthatlevelandatthatperiodlongremainedabsolutelystationary。Inthecaseofterracesformedofgravelorsand，althoughtheelevationmayhavebeenstrictlyhorizontal，itmaywellhappenthatnoonelevelbeach-linemaybetraceable，andthatneithertheterracesthemselvesnorthesummitnorbasaledgesoftheirescarpmentsmaybehorizontal。 Finally，comparingtheextentoftheelevatedarea，asdeducedfromtheupraisedrecentorganicremains，onthetwosidesofthecontinent，wehaveseenthatontheAtlantic，shellshavebeenfoundatintervalsfromEasternTierradelFuegofor1，180milesnorthward，andonthePacificforaspaceof2，075miles。Foralengthof775miles，theyoccurinthesamelatitudesonbothsidesofthecontinent。Withouttakingthiscircumstanceintoconsideration，itisprobablefromthereasonsassignedinthelastchapter，thattheentirebreadthofthecontinentinCentralPatagoniahasbeenupliftedinmass;butfromotherreasonstheregiven，itwouldbehazardoustoextendthisconclusiontoLaPlata。Fromthecontinentbeingnarrowinthesouthern-mostpartsofPatagonia，andfromtheshellsfoundattheInnerNarrowsoftheStraitofMagellan，andlikewisefarupthevalleyoftheSantaCruz，itisprobablethatthesouthernpartofthewesterncoast，whichwasnotvisitedbyme，hasbeenelevatedwithintheperiodofrecentMollusca：ifso，theshoresofthePacifichavebeencontinuously，recently，andinageologicalsensesynchronouslyupraised，fromLimaforalengthof2，480nauticalmilessouthward，——adistanceequaltothatfromtheRedSeatotheNorthCapeofScandinavia！ CHAPTERIII。ONTHEPLAINSANDVALLEYSOFCHILE：——SALIFEROUSSUPERFICIAL DEPOSITS。 Basin-likeplainsofChile;theirdrainage，theirmarineorigin。 Marksofsea-actionontheeasternflanksoftheCordillera。 Slopingterrace-likefringesofstratifiedshinglewithinthevalleysoftheCordillera;theirmarineorigin。 BouldersinthevalleyofCachapual。 HorizontalelevationoftheCordillera。 Formationofvalleys。 Bouldersmovedbyearthquake-waves。 Salinesuperficialdeposits。 BedofnitrateofsodaatIquique。 Salineincrustations。 Salt-lakesofLaPlataandPatagonia;purityofthesalt;itsorigin。 ThespacebetweentheCordilleraandthecoastofChileisonarudeaveragefromeightytoaboveonehundredmilesinwidth;itisformed，eitherofanalmostcontinuousmassofmountains，ormorecommonlyofseveralnearlyparallelranges，separatedbyplains;inthemoresouthernpartsofthisprovincethemountainsarequitesubordinatetotheplains; inthenorthernpartthemountainspredominate。 Thebasin-likeplainsatthefootoftheCordilleraareinseveralrespectsremarkable;thatonwhichthecapitalofChilestandsisfifteenmilesinwidth，inaneastandwestline，andofmuchgreaterlengthinanorthandsouthline;itstands1，750feetabovethesea;itssurfaceappearssmooth，butreallyfallsandrisesinwidegentleundulations，thehollowscorrespondingwiththemainvalleysoftheCordillera：thestrikingmannerinwhichitabruptlycomesuptothefootofthisgreatrangehasbeenremarkedbyeveryauthorsincethetimeofMolina。(Thisplainispartiallyseparatedintotwobasinsbyarangeofhills;thesouthernhalf，accordingtoMeyen(“ReiseumErde“Th。1s。274)，fallsinheight，byanabruptstep，ofbetweenfifteenandtwentyfeet。)NeartheCordilleraitiscomposedofastratifiedmassofpebblesofallsizes，occasionallyincludingroundedboulders：nearitswesternboundary，itconsistsofreddishsandyclay，containingsomepebblesandnumerousfragmentsofpumice，andsometimespassesintopuresandorintovolcanicashes。AtPodaguel，onthiswesternsideoftheplain，bedsofsandarecappedbyacalcareoustuff，theuppermostlayersbeinggenerallyhardandsubstalagmitic，andtheloweroneswhiteandfriable，bothtogetherpreciselyresemblingthebedsatCoquimbo，whichcontainrecentmarineshells。Abrupt，butrounded，hummocksofrockriseoutofthisplain：thoseofSta。LuciaandS。Cristovalareformedofgreenstone-porphyryalmostentirelydenudedofitsoriginalcoveringofporphyriticclaystonebreccia; ontheirsummits，manyfragmentsofrock(someofthemkindsnotfoundinsitu)arecoatedandunitedtogetherbyawhite，friable，calcareoustuff，likethatfoundatPodaguel。WhenthismatterwasdepositedonthesummitofS。Cristoval，thewatermusthavestood946feetabovethesurfaceofthesurroundingplain。(Or2，690feetabovethesea，asmeasuredbarometricallybyMr。Eck。Thistuffappearstotheeyenearlypure;butwhenplacedinaciditleavesaconsiderableresidueofsandandbrokencrystals，apparentlyoffeldspar。Dr。Meyen(“Reise“Th。1s。269)sayshefoundasimilarsubstanceontheneighbouringhillofDominico(andIfounditalsoontheCerroBlanco)，andheattributesittotheweatheringofthestone。InsomeplaceswhichIexamined，itsbulkputthisviewofitsoriginquiteoutofthequestion;andIshouldmuchdoubtwhetherthedecompositionofaporphyrywould，inanycase，leaveacrustchieflycomposedofcarbonateoflime。Thewhitecrust，whichiscommonlyseenonweatheredfeldspathicrocks，doesnotappeartocontainanyfreecarbonateoflime。)