首页 >出版文学> Travels and Researches in South Africa>第83章
  Whilepassingacrosstheseinterminable-lookingplains,theeyerestswithpleasureonasmallflower,whichexistsinsuchnumbersastogiveitsownhuetothegroundOnebroadbandofyellowstretchesacrossourpathOnlookingattheflowerswhichformedthisgoldencarpet,wesaweveryvarietyofthatcolor,fromthepalestlemontotherichestorangeCrossingahundredyardsofthis,wecameuponanotherbroadbandofthesameflower,butblue,andthiscolorisvariedfromthelightesttinttodarkblue,andevenpurple。
  Ihadbeforeobservedthesameflowerpossessingdifferentcolorsindifferentpartsofthecountry,andonceagreatnumberofliver-coloredflowers,whichelsewherewereyellowEventhecolorofthebirdschangedwiththedistrictwepassedthrough;butneverbeforedidIseesuchamarkedchangeasfromyellowtoblue,repeatedagainandagainonthesameplainAnotherbeautifulplantattractedmyattentionsostronglyontheseplainsthatIdismountedtoexamineit。
  TomygreatdelightIfoundittobeanoldhomeacquaintance,aspeciesofDrosera,closelyresemblingourownsundew`DroseraAnglia’。
  Theflower-stalkneverattainsaheightofmorethantwoorthreeinches,andtheleavesarecoveredwithreddishhairs,eachofwhichhasadropofclammyfluidatitstip,makingthewholeappearasifspangledoverwithsmalldiamondsInoticeditfirstinthemorning,andimaginedtheappearancewascausedbythesunshiningondropsofdew;
  but,asitcontinuedtomaintainitsbrilliancyduringtheheatoftheday,Iproceededtoinvestigatethecauseofitsbeauty,andfoundthatthepointsofthehairsexudedpureliquid,in,apparently,capsulesofclear,glutinousmatterTheywerethuslikedewdropspreservedfromevaporationTheclammyfluidisintendedtoentrapinsects,which,dyingontheleaf,probablyyieldnutrimenttotheplant。
  DuringourseconddayonthisextensiveplainIsufferedfrommytwenty-seventhattackoffever,atapartwherenosurface-waterwastobefoundWeneverthoughtitnecessarytocarrywaterwithusinthisregion;andnow,whenIwasquiteunabletomoveon,mymensoonfoundwatertoallaymyburningthirstbydiggingwithsticksafewfeetbeneaththesurfaceWehadthusanopportunityofobservingthestateoftheseremarkableplainsatdifferentseasonsoftheyear。
  Nextdaywepursuedourway,andonthe8thofJunewefordedtheLotembwatotheN。WofDilolo,andregainedourformerpath。
  TheLotembwahereisaboutamilewide,aboutthreefeetdeep,andfullofthelotus,papyrus,arum,mat-rushes,andotheraquaticplants。
  Ididnotobservethecourseinwhichthewaterflowedwhilecrossing;
  but,havingnoticedbeforethattheLotembwaontheothersideoftheLakeDiloloflowedinasoutherlydirection,IsupposedthatthiswassimplyaprolongationofthesameriverbeyondDilolo,andthatitroseinthislargemarsh,whichwehadnotseeninourprogresstotheN。WButwhenwecametotheSouthernLotembwa,wewereinformedbyShakatwalathattheriverwehadcrossedflowedinanoppositedirectionnotintoDilolo,butintotheKasai。
  Thisphenomenonofariverrunninginoppositedirectionsstruckevenhismindasstrange;and,thoughIdidnotobservethecurrent,simplyfromtakingitforgrantedthatitwastowardthelake,Ihavenodoubtthathisassertion,corroboratedasitwasbyothers,iscorrect,andthattheDiloloisactuallythewatershedbetweentheriversystemsthatflowtotheeastandwest。
  Iwouldhavereturnedinordertoexaminemorecarefullythismostinterestingpoint,but,havinghadmylowerextremitieschilledincrossingtheNorthernLotembwa,Iwasseizedwithvomitingofblood,and,besides,sawnoreasontodoubtthenativetestimony。
  ThedistancebetweenDiloloandthevalleysleadingtothatoftheKasaiisnotmorethanfifteenmiles,andtheplainsbetweenareperfectlylevel;
  and,hadIreturned,IshouldonlyhavefoundthatthislittlelakeDilolo,bygivingaportiontotheKasaiandanothertotheZambesi,distributesitswaterstotheAtlanticandIndianOceansIstatethefactexactlyasitopenedtomyownmind,foritwasonlynowthatIapprehendedthetrueformoftheriversystemsandcontinentIhadseenthevariousriversofthiscountryonthewesternsideflowingfromthesubtendingridgesintothecentre,andhadreceivedinformationfromnativesandArabsthatmostoftheriversontheeasternsideofthesamegreatregiontookasomewhatsimilarcoursefromanelevatedridgethere,andthatallunitedintwomaindrains,theoneflowingtothenorthandtheothertothesouth,andthatthenortherndrainfounditswayoutbytheCongotothewest,andthesouthernbytheZambesitotheeast。
  Iwasthusonthewatershed,orhighestpointofthesetwogreatsystems,butstillnotmorethan4000feetabovethelevelofthesea,and1000feetlowerthanthetopofthewesternridgewehadalreadycrossed;
  yet,insteadofloftysnow-cladmountainsappearingtoverifytheconjecturesofthespeculative,wehadextensiveplains,overwhichonemaytravelamonthwithoutseeinganythinghigherthananant-hilloratreeIwasnotthenawarethatanyoneelsehaddiscoveredtheelevatedtroughformofthecentreofAfrica。
  Ihadobservedthattheoldschistoserocksonthesidesdippedintowardthecentreofthecountry,andtheirstrikenearlycorrespondedwiththemajoraxisofthecontinent;andalsothatwherethelatereruptedtraprockshadbeenspreadoutintabularmassesoverthecentralplateau,theyhadborneangularfragmentsoftheolderrocksintheirsubstance;butthepartialgeneralizationwhichtheobservationsledtowas,thatgreatvolcanicactionhadtakenplaceinancienttimes,somewhatinthesamewayitdoesnow,atdistancesofnotmorethanthreehundredmilesfromthesea,andthatthisigneousaction,extendingalongbothsidesofthecontinent,hadtiltedupthelateralrocksinthemannertheyarenowseentolieThegreaterenergyandmoreextendedrangeofigneousactioninthoseveryremoteperiodswhenAfricawasformed,embracingalltheflanks,impartedtoititspresentverysimpleliteraloutlineThiswasthelengthtowhichIhadcome。
  Thetraprocks,whichnowconstitutethe“fillingup“ofthegreatvalley,werealwaysapuzzletometillfavoredwithSirRoderickMurchison’sexplanationoftheoriginalformofthecontinent,forthenIcouldseeclearlywhythesetraprocks,whichstilllieinaperfectlyhorizontalpositiononextensiveareas,heldintheirsubstanceangularfragments,containingalgaeoftheoldschists,whichformthebottomoftheoriginallacustrinebasin:thetraps,inburstingthrough,hadbrokenthemoffandpreservedthem。
  Thereare,besides,rangesofhillsinthecentralparts,composedofclayandsandstoneschists,withtheripplemarkdistinct,inwhichnofossilsappear;butastheyareusuallytiltedawayfromthemassesofhorizontaltrap,itisprobablethattheytoowereaportionoftheoriginalbottom,andfossilsmayyetbefoundinthem。*
  *AfterdwellinguponthegeologicalstructureoftheCapeColonyasdevelopedbyMrABain,andtheexistenceinveryremoteperiodsoflacustrineconditionsinthecentralpartofSouthAfrica,asprovedbyfresh-waterandterrestrialfossils,SirRoderickMurchisonthuswrites:
  “SuchasSouthAfricaisnow,suchhavebeenhermainfeaturesduringcountlesspastagesanteriortothecreationofthehumanrace;
  fortheoldrockswhichformherouterfringeunquestionablycircledroundaninteriormarshyorlacustrinecountry,inwhichtheDicynodonflourished,atatimewhennotasingleanimalwassimilartoanylivingthingwhichnowinhabitsthesurfaceofourglobeThepresentcentralandmeridianzoneofwaters,whetherlakesormarshes,extendingfromLakeTchadtoLake’Ngami,withhippopotamiontheirbanks,arethereforebutthegreatmodernresidualgeographicalphenomenaofthoseofamesozoicageThedifferences,however,betweenthegeologicalpastofAfricaandherpresentstateareenormous。
  Sincethatprimevaltime,thelandshavebeenmuchelevatedabovethesea-leveleruptiverockspiercinginpartsthroughthem;
  deeprentsanddefileshavebeensuddenlyformedinthesubtendingridgesthroughwhichsomeriversescapeoutward。
  “Travelerswilleventuallyascertainwhetherthebasin-shapedstructure,whichishereannouncedashavingbeenthegreatfeatureofthemostancient,asitisoftheactualgeographyofSouthAfricai。e。,fromprimevaltimestothepresentday,does,ordoesnot,extendintoNorthernAfricaLookingatthatmuchbroaderportionofthecontinent,wehavesomereasontosurmisethatthehighermountainsalsoform,inageneralsense,itsflanksonly。”President’sAddress,RoyalGeographicalSociety,1852,pcxxiii。
  ThecharacteristicsoftherainyseasoninthiswonderfullyhumidregionmayaccountinsomemeasurefortheperiodicalfloodsoftheZambesi,andperhapstheNileTherainsseemtofollowthecourseofthesun,fortheyfallinOctoberandNovember,whenthesunpassesoverthiszoneonhiswaysouthOnreachingthetropicofCapricorninDecember,itisdry;
  andDecemberandJanuaryarethemonthsinwhichinjuriousdroughtsaremostdreadednearthattropicfromKolobengtoLinyanti。
  AshereturnsagaintothenorthinFebruary,March,andApril,wehavethegreatrainsoftheyear;andtheplains,whichinOctoberandNovemberwerewellmoistened,andimbibedrainlikesponges,nowbecomesupersaturated,andpourforththosefloodsofclearwaterwhichinundatethebanksoftheZambesiSomewhatthesamephenomenonprobablycausestheperiodicalinundationsoftheNileThetworiversriseinthesameregion;butthereisadifferenceintheperiodofflood,possiblyfromtheirbeingonoppositesidesoftheequator。
  ThewatersoftheNilearesaidtobecometurbidinJune;
  andthefloodattainsitsgreatestheightinAugust,ortheperiodwhenwemaysupposethesupersaturationtooccurThesubjectisworthytheinvestigationofthosewhomayexaminetheregionbetweentheequatorand10DegS。;fortheNiledoesnotshowmuchincreasewhenthesunisatitsfarthestpointnorth,ortropicofCancer,butatthetimeofitsreturningtotheequator,exactlyasintheothercasewhenheisonCapricorn,andtheZambesiisaffected。*
  *Theaboveisfrommyownobservation,togetherwithinformationderivedfromthePortugueseintheinteriorofAngola;andImayaddthattheresultofmanyyears’observationbyMessrsGabrielandBrandatLoanda,onthewestcoast,isinaccordancetherewith。
  Itrainstherebetweenthe1stand30thofNovember,butJanuaryandDecemberareusuallybothwarmanddry。
  Theheavierrainscommenceaboutthe1stofFebruary,andlastuntilthe15thofMayThennorainfallsbetweenthe20thofMayandthe1stofNovemberTherainaveragesfrom12to15inchesperannumIn1852itwas12。034inches;
  in1853,15。473inchesAlthoughIhadnomeansofmeasuringtheamountofrainwhichfellinLonda,Ifeelcertainthattheannualquantityexceedsverymuchthatwhichfallsonthecoast,becauseforalongtimewenoticedthateverydawnwasmarkedbyadelugingshower,whichbeganwithoutwarning-dropsorthunder。
  Iobservedthattherainceasedsuddenlyonthe28thofApril,andthelesserrainscommencedaboutafortnightbeforethebeginningofNovember。
  FrominformationderivedfromArabsofZanzibar,whomImetatNalieleinthemiddleofthecountry,theregiontotheeastofthepartsofLondaoverwhichwehavetraveledresemblestheminitsconformation。
  Theyreportswampysteppes,someofwhichhavenotrees,wheretheinhabitantsusegrass,andstalksofnativecorn,forfuel。
  Alargeshallowlakeisalsopointedoutinthatdirection,namedTanganyenka,whichrequiresthreedaysforcrossingincanoes。
  ItisconnectedwithanothernamedKalagweGarague?,farthernorth,andmaybetheNyanjaoftheMaravimFromthislakeisderived,bynumeroussmallstreams,theRiverLoapula,theeasternbranchoftheZambesi,which,comingfromtheN。E。,flowspastthetownofCazembe。
  ThesouthernendofthislakeistendaysnortheastofthetownofCazembe;
  andasthatisprobablymorethanfivedaysfromShinte,wecannothavebeennearertoitthan150milesProbablythislakeisthewatershedbetweentheZambesiandtheNile,asLakeDiloloisthatbetweentheLeebaandKasaiBut,howeverthismaybe,thephenomenaoftherainyseasonshowthatitisnotnecessarytoassumetheexistenceofhighsnowymountainsuntilwegetreliableinformation。
  This,itistobehoped,willbeoneoftheresultsoftheresearchesofCaptainBurtoninhispresentjourney。
  TheoriginalvalleyformationofthecontinentdeterminedthenorthernandsoutherncourseoftheZambesiinthecentre,andalsooftheancientriverwhichonceflowedfromtheLinyantibasintotheOrangeRiverItalsogavedirectiontothesouthernandnorthernflowoftheKasaiandtheNileWefindthatbetweenthelatitudes,say6Degand12DegS。,fromwhich,inallprobability,theheadwatersofthoseriversdiverge,thereisasortofelevatedpartitioninthegreatlongitudinalvalleyPresumingonthecorrectnessofthenativeinformation,whichplacesthehumidregiontowhichtheNileandZambesiprobablyowetheiroriginwithinthelatitudesindicated,whydoessomuchmorerainfalltherethaninthesamelatitudesnorthoftheequator?WhydoesDarfurnotgiverisetogreatrivers,likeLondaandthecountryeastofit?TheprevailingwindsintheoceanoppositetheterritorypointedoutaresaidtobefromtheN。EandS。E。