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Hydrographic Sketch of Lake TiticacaAuthor(s): Alexander AgassizSource: Proceedings of the American Academy of Arts and Sciences, Vol. 11 (May, 1875 -May, 1876), pp. 283-292Published by: American Academy of Arts & Sciences

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OF ABTS AND SCIENCES. 288

XXIV.

HYDROGRAPHIC SKETCH OF LAKE TITICACA.

By Alexander Agassiz.

Presented, March 8, 1876.

From the positionof Lake Titicaca, its

exploration promisedto

give interesting results inNatural History, judging at least from the

materials collected in lakes situated at great heights.It was there

fore with considerable disappointment that my companion andmyself!

after aprotracted examination of this great sheet of water examined

ourplunder. We had come

prepared with all the necessary apparatus

fordredging,

fortaking observations of temperature and

making

soundings ; and, with the facilities placed at my command by the

Peruviangovernment,

wehoped

togather

a rich harvest. Mr. Gar

manspent nearly

six weeks inskirting

the shores of the lake, stop

pingat all convenient

placesfor

makingcollections of the Fauna of

the lake and of its shores, and forexploring the ancient remains found

on the islands in the lake and at several points in thevicinity

of the

shore line. While Mr. Garman wassailing

on the lake in a small iron

sloop, the only sailingvessel on the lake, if we

exceptan old flat bot

tomferry plying

across the Straits ofTiquina,

I made twoexpedi

tions in the steamers"

Yavari"

and"

Yapura

"

placedat my disposal

by the Peruvian government, landing at all the noted points where

interestingInca ruins existed : the islands in the lower lake, the islands

of Coati and of Titicaca, Copacabana, andTiaguanaco. During

these

twoexpeditions, I crossed the lake

longitudinally twice, and ran sev

eral lines ofsoundings

from shore to shore. The captainsof the

government steamers, Capt.F. Guerrero especially, taking

the great

est interest in my proceedingsand

assistingme in all

possible ways,

sparing neither time norpains to secure proper observations. The first

mate of the"

Yavari"

wasfortunately

assistedby

a number ofEnglish

sailors, who were devoted inhauling

thesounding

lines at all times of

the day and during all kinds of weather. The sketch map accompany

ingthis notice is

compiled from the map of Thompsonand of Pentland,

with such corrections of the shore line as we could make from per





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284 proceedings of the American academy

sonal examination. The latitude asgiven by Pentland, 16? S. for

the northern extremityof the Island of Titicaca, is very nearly

cor

rect, Capt. Guerrero and myself havingtaken several sextant observa

tions off the northwest point of the island, whichagreed quite closely

with Pentland's positions.The

longitudeof Puno, however,

asgiven

by Pentland, 70? W., isprobably

notquite correct, and too far to the

eastward. The distance of Puno from the harbor of Moliendobeing

onlyseven minutes in time, as ascertained by telegraph

between the

two points, of course this is approximate ; while taking the longitudes

asgiven

on the English admiralty map 73? 39' for Moliendo,as

given

by Fitzroy,and 70^ for Puno, by Pentland, the difference of

longi

tude is somewhat greater,more than 3?.

Mr. Garman andmyself took more than

sixty-five soundings,from

which a number were selected to represent the surface of the bottom.

The whole bottom of the lake in its deepest parts, andfrequently quite

close to the shore, up to the pointat which the

myriophyllumand the

totora growso

plentifullyin certain localities, is covered

bya thick

bed of mud, the finest possible greenish black silt. This bed of mud

must have been several feet in thickness, to judge from the ease with

which theheavy sounding

leadsdisappeared

in it. It contained but

few fragmentsof shells, being

almost alwaysmade up of pure fine

mud. It wasonly

in a small number of localities near the shore, and

away from the mouth of any rivers, that occasional patchesof sand

and ofshelly

orrocky

bottom were found. In the lower lake,

however, the bottom wasgenerally sandy,

the waterhaving deposited

the bulk of the matter held in suspense before reachingthe Straits of

Tiquina.At the time of our visit to the lake, although during the

last part of the rainy season, when all the rivers pouringinto the lake

werevery high

and turbid with the mud and materialsthey brought

down

from the mountains, yet,a short distance from the shore, the surface

water wasremarkably pure and clear. According

to ananalysis

made

byProfessor Raimondi of Lima, there is but a mere trace of saline sub

stances, and not sufficiently largeto affect the potability

of the water.

Havingan outlet to Lake Aullagas through

theDesaguadero,

there is

no chance for an accumulation of saline matter, while LakeAullagas

is already,as I am told, somewhat saline, and the sink into which that

pours is quite saline. The unpleasanttaste of the lake water near the

shore is due to the immense amount of decayed vegetablematter

aboundingin the extensive fields of

myriophyllum

and of totora,

which line the shores for miles, and which ex ten 1 to adepth

of from

six to seven fathoms. The totora fields are most extensive in Puno





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OF ARTS AND SCIENCES. 285

Bayand the southern shores of the lower lake. The myriophyllum

grows very luxuriantly,and forms an

importantarticle of food for the

cattle of the lake shore. It is not an uncommonsight

to see the

cows of Punowading up to their middle in the water, and

diving

boldly in search of their food which they cannot find on the shore.

This habit has asyet produced

noapparent effect on these amphibious

cows, althoughcarried on for a

good many generations.The fields of

Totora are also thefeeding places

of themyriads

of aquatic birds

which abound along the lake shore, and which are the most charac

teristic feature of the Fauna of the lake. The fishes andreptiles

are

not numerous,* and our collections of the former showed apoverty in

specieswhich is most remarkable, and this is also accompanied by

a

comparative poverty in the number of specimens, except in certain

localities. Thescarcity

of fishes can, however, bereadily explained

when we examine thephysical

condition of the water, which is cer

tainlynot well adapted

to them. In the firstplace,

the whole bottom

of the lake, as I have mentioned before, is covered with silt, thus ren

deringunfit a

large part of the area of the lake for the fishes and rep

tiles, leaving only the shallower bays, a more or less wide belt along

the shoreaccording

to the nature of theadjoining country, and the

lower lake, which appears to be the favoritefishing post of the Indians.

This, however, may be due to the greater energy of the Bolivian In

dians, who are a finer set of men, morewilling

to work, and inevery

way superior to the lazy natives found near Puno and the northern end

of the lake. In the second place, the temperature of the water of the

lake is sohigh

that none of the fishes which abound in the lakes of

ourtemperate

zone are to be found. There are in allonly

six species

of fishes, Cyprinoidsand Siluroids,?a remarkably

small number for

a sheet of water as large as Lake Erie. They were all known before.

In the wray ofreptiles,

the mostinteresting species

was ahuge frog,

which remained often for hours perfectly quieton the bottom, sus

pendedon fronds of

myriophyllum, apparently toolazy

to come up

to the surface to breathe.

The effect of the vertical sun upon the temperature of the water is

very marked, extendingto its deepest point, and

heatingthe whole

body of water to such an extent that thegreatest difference we ob

served was in one case, it is true, ashigh

as6J degrees

at adepth

of 103 fathoms; but the usual difference between the surface and

* See Bull M. C. L. Vol. III. No. 11.





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286 PROCEEDINGS OF THE AMERICAN ACADEMY

the bottom, even at the greatest depth (154 fathoms),was not more

than from 3 to 4degrees.

The lowest temperature of the bottom

wasonly 51?, the

general temperature varyingfrom 54 to 55?; while

the surface temperature rangedfrom 53 to 59?, the greater part of

the time 56 to 57? Fahr.

We used theordinary deep-sea thermometer of Miller Casella,

kindlyloaned to me

by Captain Patterson of the United-States Coast

Survey.As is well known, deep-sea observations show that the effect

of the sun does not extend in the ocean much beyond 50 fathoms; but,

in a closed basin like this, at sogreat

an altitude, the effect of the direct

rays of the sunpassing through

so little atmosphere is very great.

It must be remembered, that, even in the winter months of that re

gion (the dry season),the sun never

goes farther north than 52?, and

thatonly

for a short time ; and that, in the summer months(the rainy

season),it is

nearly vertical the greater part of the time. The water,

of course, retains its heatreadily, and, even in summer, is but little

cooler than thesurrounding air, which becomes very rapidly

chilledby

the least cloudinterposing

between it and the sun. It is avery com

mon thing for the thermometer to rise or fall eight or nine degrees in

as many minutes from the effect of the sudden appearance ordisap

pearance of the sun. Ice is said to form onlyin small quantities

alongthe shores or shallow places

: this is easily imaginedwhen we

take into account the immense body of water which must be cooled,

120 mileslong by

30 wide, and anaverage depth of about 100 fath

oms ; the surface of the lake, even in winter, receivinga

largeamount

of heat by absorption, althoughthe air itself is

uncomfortably cold.

We find here, as is the case in many other sheets of water com

paratively isolated, but few species,and these peculiar

to the lake.

We find at thisgreat

elevation a condition ofthings reminding

us of

the marine life of arcticregions,

? agreat abundance of specimens,

with acomparatively

small number ofspecies ; the shoals of Orestias

and Siluroids, which are seen in certain localities, agree with the ac

counts we have of the swarms of fishes and other animalshaunting

the

arctic realms. Still there arepeculiar physical

conditions of the bot

tom of the lake, the immense depositsof mud formed by the

settling

of the siltbrought

down annually bythe mountain-streams, the great

elevation of the lake, the high temperature of the water ; all of

which causes should tend tospecialize

to a remarkabledegree

the

genera

found to thrive in such a condition of

things.

We find, how

ever, no such specialization broughtabout among the fishes : on the

contrary, their isolation, even whileliving

under such peculiar physical





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conditions, appears to havedeprived

some of them, at any rate, of

any capacityfor development in the direction of their congeners.

The genus Orestias isclosely

allied to Fundulus, one of the most

widelydistributed of fresh-water genera. The species of the genus

Orestias resemble in a remarkabledegree

the young of somespecies

of Fundulus, andmight

be considered, withoutexaggeration,

its em

bryonic type,at a time when the young Fundulus is remarkable for

itslarge head, prominent opercula, its

largescales

resembling plates

along the anterior part of the back and sides. The other genera of

fish found in the lakes areeminently fresh-water, having

agreat

geographical distribution. The great number of water-birds recalls

to usvividly also the more northern

marshy regions,where thousands

of ducks and water-hens abound. The mollusca are all species of

eminentlyfresh-water genera, showing nothing very special. The

Crustacea, on the other hand, belong mainlyto the Orchestiadas, forms

which thus far have not been found in fresh water at all : their near

est allies arenearly all marine (see Bull M. C. L., vol. iii. No.

16).

Althoughwe have from the researches of several

geologists,but of

Darwin mainly,a

pretty good general idea of the immense extent of

territorywhich has been subject

to agreater

or less elevationalong

the wrhole west coast of South America, from the south coast of Ecua

dor to the eastern coast ofPatagonia,

this elevation appears to have

culminated in Central Peru. Yet there has beennothing

shown which

would lead us to assume such an immense elevation of the land as

12,000 feet. It is very true that Darwin showed the mostpositive

proof of elevation to aheight of about 600 feet ; while terraces,

shingle-beaches,and other more or less distinct traces of the former

level of the sea, he traced to aheight

of from 1,300-1,500 feet. I

have been able to follow

up

these traces of elevation somewhat

higher,

havingfound at Tilibiche, at a

heightof 2,900 feet above the level of

the sea, corals of genera closelyallied to those now found

livingin

the West Indies (seeBull M. C. L., vol. iii. No.

13).These corals

were attached to rocks, in crevasses formed between them, much as

we would find them attached at the present dayin the cracks of rocks.

This beingnear the northern

extremityof the nitrate-fields of Peru,

throws considerable light on the probability of these deposits having

been of marineorigin.

In fact, thegeography

of the whole of the

west coast of the Andes to the north of Chili seems to pointto a

former condition of

things

such as we now find on the west coast of

Chili. The plainsto the southward of

Santiago,bounded by the coast

rangeto the westward, and the Andes to the east, gradually pass to





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288 PROCEEDINGS OF THE AMERICAN ACADEMY

the condition of the coast nowprevailing

atConception Bay, and south

of it,? the coast range formingthe

archipelago,the Andes

formingthe

coastrange, and the

plainsof the more northern

regions becoming

changedto

bays ; the immense basinssucceeding

each other towards

the north which form the so-called Desert of Atacama, the nitrate-beds,

the llanos of the coast, the pampas of Peru, throughwhich the rivers

flowingto the west have cut

deep valleys with more or less marked

terraces, showingthe different periods

of ascent in the elevation of the

continent. These plainsare

everywhere found, either between a

coast range and the base of the eastern talus of the Andes, or ex

tendingfrom the summit of the shore terrace, if we

mayso call it,

generallyat a

heightof from 1,200 or 3,000 feet, sloping

to the

second terrace, with its base at anaverage height

of from 6,000

7,000 feet, and then followedby

a second and third more or less

indistinct terrace until we reach the main elevatedplateau

or basin

which lies between the eastern and westernslope of the Andes. All

these basins show more or lessdistinctly the trace of their former

marineorigin ; so that, if we are to

judgefrom the presence of

strictly

marine forms, the successive terracesdeveloped

on amagnificent

scale

on the west coast of the Andes, with the interlying basins, we have

a fair presumption that the elevation of the Andes to their present

heighthas taken

placeat a

comparativelyrecent date, and

duringtheir

upheaval the present nitrate district and saline depositswere left as

large lagoons duringa considerable period, to

judgefrom the great

thickness of thedeposits found within their basins, all

denotingthe

presence of acomparatively quiet inland sea.

Lake Titicaca itself must have, within acomparatively very recent

geological period, formed quitean inland sea. The terraces of its

former shores areeverywhere

mostdistinctly

to be traced, showing

that its water-level must have had an elevation of 300 or 400 feet at

leasthigher

than its present level. This alone would send its shores

far to the north in the direction of Pucar?, forminga narrow arm

reaching up to S. Rosa. Lake Arapais

probably onlyan outlier of

the ancient lake, as well as several of the small lakes, now at a

considerable distance from the west shore. The immenseplain of

Cabanillas, extendingnorth

beyond Lampato Juliaca, only

100 or

120 feet above the lake at itshighest point,

was one sheet of water.

The terraces of the former shores are still very distinctlyseen. The

eastern shores did notprobably

differgreatly

from the present out

line, though the peninsula of Achacache was probably an island.

TheBay

of Puno must have been connected with the plains of Llave,





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and those back of Juli ; while from the lower lake, back of Aygache,the lake formed

hugeinlets or

deep bays,now

represented only by

thenearly dry

river-bedsflowing

into the lake atAygache, Corilla,

andGuajui.

Thesluggish Desaguadero

must have been a strait of

considerable width, withlarge

islands ; and thislong lake, connecting

Lake Titicaca with LakeAullagas,

must haveequalled

in extent the

upper lake ; the upper lake, at that time, extendingacross the Isth

mus ofYunguyu, leaving

the Peninsula ofCopacabana

as alarge

island, connected with the lower lakeby

a broad pass between the

hills to the west of Copacabana, and those to the west of Yunguyu.

The plains,now laid bare at the northern and western shores of Lake

Titicaca, giveus an excellent idea the appearance the whole basin of

the lake would present ifentirely dry. The number of lakes and

basins, great and small, whichformerly covered the elevated

plateau

of the Andes, must have been very great ; but we now findonly

here and there a small sheet of water. The former lakes areonly

represented by the more or less extensive pampas, formingbasins at

great altitudes, showing plainlythat the whole of this district is re

ceivinga much smaller waterfall than in former times, but

probably

not within historic times, if we take into consideration the position

of some of the most ancient ruins of Bolivia(at Tiahuanaco),

which

areonly

about 75 feet above the present level of the lake. These

ancient basins arethickly

coveredby huge

bunches of rank grass,

from which the llamas, alpacas,and vicu?as obtain their only

suste

nance at the immenseheights

wherethey

seem best to prosper. It

would be aninteresting inquiry

to ascertain the causes of the differ

ence in the habitat between the otherspecies

of camels and the

llamas, which do not thrive near the sea-coast.

In the lower lake, which is shallow, the temperature of the surface

and that of the bottom varied extremely. From the number of obser

vations taken, I canonly

state that it is very local, depending upon

the prevailingwind and the condition of the

sky.

Thefollowing soundings,

taken from those of the upper lake, show

the great uniformityof the temperature of the surface and bottom:

?

vol. xi. (n. s. III.) 19





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290 PROCEEDINGSOF THE AMERICANACADEMY

Depth.Fath.

28

18

12

24

33

30

43

47

66

74

82

85

90

100103111106112113

114

116124

125

130

136132

149150151154

Surface.

55? F.

55

58

59

55

56.5

54.7

57.5

56.7

55.9

56.1

57

55.5

56

56

55.3

56

57.5

57

54.9

57.5

5556. 3

55

56

57

53

55.3

55

55.4

54

Bottom.

55? F.

53

53

54.5

54.9

56

54.5

56.2

55

54.9

54.3

54.5

51

54

54

54.3

51.5

54.9

54.5

54.5

55

55

54.656

54.9

55

54

52

54.5

54.5

55

52

Air. Time.

7.40 a.m.

56? 10.15 a.m.

12.30 a.m.

55 4.30 p.m.

42 7.10 a.m.

53 9 a.m.

47 12.20 a.m.,cloudy.58.5 4 p.m., clear.

58 10.20 a.m.

67 11.05 p.m., sun very bright.55 11.10 p.m., sunny.60 2.25 p.m., sunny.

8 a.m.

43 6 a.m., rainy.55 1 p.m.

44 7.10 a.m., raining hard.

6.15 p.m.

63 12.20 p.m., clear.

44 7.10 p.m., raining hard.

61 10 a.m., clear.

45 11.14 a.m., raining hard.60 1.09 p.m., sunny.45 8.05 p.m., sunny.

9.10 p.m.

55 10.30 a.m.

47 11.40 a.m., cloudy.48 10.25 a.m., cloudy.49 12.25 p.m.

8.45 a.m.

The elevation of the lake above the Pacific has been taken from the

surveys of the railroad engineers, obtained while laying the line from

Arequipato Puno. Professor James Orton inclines to the

opinion

that the whole basin of Lake Titicaca, with the high plateau to the

westward, isgradually sinking,

because the successive observations

made fromearly

timesgive

agradually diminishing height.

Thus

far, the few measurements taken canhardly

be more than a chance

coincidence, when we remember theuncertainty

andgreat divergence

attendingall measurements of

heightstaken to within a

comparatively

veryrecent

period.The experience of the

topographersof the late

geological surveys in theRocky Mountains has been very similar ; and

yetwe are

hardly preparedfor such a

sweeping generalizationas

thesinking

of the greater part of the Rocky Mountains from much





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more abundant data than those accessible from Lake Titicaca and its

vicinity.

Alongthe eastern coast of Lake Titicaca, the mountains

formingits

former shores nowhere rise to any considerableheight.

Thegreatest

elevations are foundalong

thegeneral

lineforming

the westernedge

of the high plateau, to the south of which the lake is situated, from the

Nevados of Tacorara to those east ofMoquega,

thePichupichu,

Chachani, Coropuno. A low*ernearly parallel range extends about

half-way between the line of the former and the axis of Lake Titi

caca. This range, however, does not rise to more than 16,000 or 17,000

feet, and, sweepingto the northward at a distance of about one hundred

miles to the north-east of the lake, forms the water-shed between the

riversleading

to the headwaters of the Amazonas and thoseflowing

into Lake Titicaca, the eastern sides of this great basinbeing

formed

bythe northern extension of the huge range which culminates near

the south-eastern shores of Lake Titicaca in the snowy giants of

Guaina Potosi, Mamini, andMampu. The range runs

nearly north

ward from the head of theBay

of Achacache, formingthe southern

boundaryof

Caravayaon the north, and

unitingwith the northern

water-shed of the great Titicaca basin. This eastern range of snowy

mountains retreats from the shore of the lake about as far as the

western intermediate range, and forms at the same time the line

between the waters flowing to the Pacific and those belonging to the

basin of the lake. The hills of thepeninsula of

Copacabana do not

rise more than 800 to 1,000 feet above the level of the lake ; and, to

the south of the lake, low ridges form thedividing-lines of the tor

rentsflowing

from theheights between La Paz and Corocoro into

the lower lake. The view from the crest of one of theseridges

im

mediatelyto the eastward of Tiahuanaco is

truly magnificent ; and the

panoramaof

snowy heights risingfrom

8,000to

10,000 feet abovethe level of the lake is one of the most beautiful stretches of mountain

scenery it has been my fortune to see.Rising

as these mountains do

behind the islands of the lower lake as aforeground, with the low

hills beyond Huarina on the opposite shore of the lake at the base of

the snow-linecoming down to within a

couple of thousand feet of the

shore, we have within a radius ofthirty-five miles no less than six or

seven peaks varying from 20,000 to 22,000 feet above the level of the

sea.Looking

over the peninsula ofCopacabana extends the upper

lake, with its sacred islands hardly visible on the horizon ;while to

the westward extend, as far as theeye

can

reach,the

huge flat-toppedhills, the

dividing-ridges between the torrentsflowing into the lake,





7/27/2019 20021479(1)


292 PROCEEDINGSOF THE AMERICAN ACADEMY

which comprise the immense elevated plateau reachinga

height of

some 16,000 feet above the level of the sea, with an endless number

of somewhat higher peaks rising slightlyabove this

generalelevation ;

while to the westward of Tiahuanaco the sharply-cut outline of the

r.:ounttin-chain which formj thediv^llng-boundars

between Bolivia

and Peru shuts out the view in that direction. But while the outline

of many of these chains is mostgraceful,

and thegrandeur

of the

Nevada de Sorata is not to beforgotfen,

the barrenness and utter

desolation of the whole scene deprives it of much of its beauty.

There isabsolutely nothing green

to rest the eye ; the whole country

isdry, arid, stony ; here and there a

patch of rank grass, upon which

the vicu?as manageto eke out their existence ; an occasional shrub,

with a stem aslarge

as one's littlefinger, only

left because it has thus

far escapedthe eye of the Indian

gatheringthe few shrubs

remaining

as the only firewood, which, with characteristic imprudence, he does

not cut down togive

it a chance to grow again,but pulls up roots and

all, toget

as much fuel for the present needs aspossible.

The accompanying map illustrates thegeneral hydrography

of the

basin of Lake Titicaca.





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20021479(1)

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