#50 
For the Monthly Magazine. 
GEOLOGICAL DESCRIPTION of SOUTH 
AMERICA. By the late F. A. VON 
HUMBOLDT.* 
VINCE I {ent to. Madrid the two firft 
 tketches of a geological delineation of 
Svoth America, irom the Caraccas and 
Wueva Valencia, I have trave'kd twelve 
hundred miles,.and dcferibed a iquare be- 
tween Caribe, Portocabello, Pimichiw, and 
Efmeralda, a {pace comprehending above 
£9,000 {quare miles; for I am not ac- 
guainted with the land between the moun- 
tain Parea and Pertocahelio, and between 
the northern coak and the valley of the 
Black River. In confequence of the great 
circumference of this diltritt, I mui con- 
tent mylelf with delineating it ina gene- 
ral manner, and, to avoid details, wath 
defcribing the conftiuction of the earth, 
the declivity of the land, the direction and 
jaclination of the mountains, their rela- 
tive ages, their fimilarity with the forma- 
tion ct thofe in Europe. Thefe are the 
circumftances moft neceflary to be known 
in this fcience. We muft procced in mi- 
neralogy aS in geography ; we are ac- 
quainted with Roses, but not with moun- 
tains ; we know the materials, but we are 
ignorant of the whole of which they form 
componest parts, I wifh I may beable, 
amidit the variety of the objef&is which oc- 
cupy my attention during my travels, to 
throw any light on the fruéture of the 
earth. The laborious journeys which, 
for eight years, 1 have made through Eu- 
rope had no other objeét 5 and if I have 
the gcad fortune to reiurn to Europe, and 
to recover my geolegica] manufcripts 
which I left behind me in France and 
Germany, I fhall venture to give a fk-tch 
ofthe &ru€iure ot the ear‘h. What I have 
long faid, that the diveétion and inelina- 
tion, the rifing and ‘alling, of the primiiive 
firata, the angles which they form with 
the meridian of the plece, and with tre 
axis of the earth, are independent ef the 
dire&ticn and depreffion of the mountains ; 
that they depend on laws, and that they 
cbferve a general parallchim which can 
be fuunded only in the motion and rota- 
tion of the earth ; what Freifleben, 
Von Buch, and Gruner, -have proved bet- 
ter than I, will be found confirmed, name- 
“ This valuable man intended to return to 
Evrope by the. way of the Manillas ; but we 
learn, that, while he was waiting for a fhip at 
Acapulco, he was feized with a fever, which 
carried hin: off in a few days. His papers 
and jqurnals are, however, om their wey to 
Europe. 
* 
Geological Defcription of South America. 
* [April ty 
Jy, that the freceffion of the alluvial ftra~ 
ta, which was confidered as a peeuliarity 
of certain provinces, fuch as Thuringia 
and Derbyfhire, takes place generally 5 
and that there appears an identity in the 
order of the ftrata; from which there is 
reafon to concluds that the fame depofi- 
tion has been effeéted at the fame time 
over the whole turface of the earth. All 
thete ideas are of the greateft importance, 
not only to the philoiopher, who endea- 
vours to elevate himielf to general princi- 
ples, but allo to the miner, whe mutt 
conceive in his mind what he has not be- 
fore his eyes, and guide himlelf by ana- 
logy deduced fyom actual exverience. 
Before I defcribe the fituation of the 
moun ains which I have obferved from 
the coaft to the province of Venezuela, I 
fhal give a genesal view of the: form of 
this continent. Unfortunately there are 
no early oblervaticns to ferve as a ground 
for this defcription. For half a century 
pat many accidental obfervations refpect- 
ing this lend have been collected, but not 
a fingle idca relating to its geology has 
heen made known. ‘7 he great genius of 
Condamine, the zeal. cf Dem George Juen 
de Ulloa, would certzinly not have left us 
in the dark on this tubjeét, had minera- 
logy been more eultivated at the time 
when they wrote. All that could then be 
done was to meafure and to take levels. 
As they were employed on the high cor- 
dillera of the Andes, which extends north 
and fouth from Zitara, as far as Cape Pi- 
lar, and beheld with wonder the smmenfe 
height of the mountains, they forgot that 
South America exhibits other cordilleras, 
which exiend eaft and wet parallel to the 
equator, and which, on eccount of their 
height, deferve as much the attention of 
naturalifts as the Carpathians, Caucafus, 
the Alps of the Valais, and the Pyrenees. 
The whole immen‘e tract on the weft fide 
of the Andes, which extends obliquely to 
the coaft of Guiana and Brafil, is deterib- 
ed asa Jow plain, expofei to the inunda- 
tion of the rivers. As cniy a few Fran- 
cifcan m flicnaries ard a few foldiers have 
been able to penetrate over the cataracts to 
Rio Negro, the inhabitants of the coatt of 
Caraceas imagine that the immenfe plains 
(the Lianos de Calabozo, dei Gvarico, 
and de Apure,) which they fee to the 
fouth, beyond the valleys of Aragua, ex- 
tend wi hcut interruption to the Pampas 
of Buenos-Ayres, ard to the country of 
the Patagoniars; but the extent of thefe 
plains is-tar from being. fo: great ; they 
are not uninterrupted plains, they are fa- 
ther phenomena of the fame kind as thofe 
prefented 
