geological description of south america.

By the late f. a. von humboldt.

This valuable man intended to return to Europe by the way of the Manillas; but we learn, that, while he was waiting for a ship at Acapulco, he was seized with a fever, which carried him off in a few days.

His papers and journals are, however, on their way to Europe.

SINCE I lent to Madrid the two first sketches of a geological delineation of South America, from the Caraccas and Nueva Valencia, I have travelled twelve hundred miles, and described a square between Caribe, Portocabello, Pimichin, and Esmeralda, a space comprehending above 59,000 square miles; for I am not acquainted with the land between the mountain Parea and Portocabello, and between the northern coast and the valley of the Black River.

In consequence of the great circumference of this district, I must content myself with delineating it in a general manner, and, to avoid details, with describing the construction of the earth, the declivity of the land, the direction and inclination of the mountains, their relative ages, their similarity with the formation of those in Europe.

These are the circumstances most necessary to be known in this science.

We must proceed in mineralogy as in geography; we are acquainted with stones, but not with mountains; we know the materials, but we are ignorant of the whole of which they form component parts.

I wish I may be able, amidst the variety of the objects which occupy my attention during my travels, to throw any light on the structure of the earth.

The laborious journeys which, for eight years, I have made through Europe had no other object; and if I have the good fortune to return to Europe, and to recover my geological manuscripts which I left behind me in France and Germany, I shall venture to give a sketch of the structure of the earth.

What I have long said, that the direction and inclination, the rising and falling, of the primitive strata, the angles which they form with the meridian of the place, and with the axis of the earth, are independent of the direction and depression of the mountains; that they depend on laws, and that they observe a general parallelism which can be founded only in the motion and rotation of the earth; what Freiesleben, Von Buch, and Gruner, have proved better than I, will be found confirmed, namely, that the succession of the alluvial strata, which was considered as a peculiarity of certain provinces, such as Thuringia and Derbyshire, takes place generally; and that there appears an identity in the order of the strata; from which there is reason to conclude that the same deposition has been effected at the same time over the whole surface of the earth.

All these ideas are of the greatest importance, not only to the philosopher, who endeavours to elevate himself to general principles, but also to the miner, who must conceive in his mind what he has not before his eyes, and guide himself by analogy deduced from actual experience.

Before I describe the situation of the mountains which I have observed from the coast to the province of Venezuela, I shall give a general view of the form of this continent.

Unfortunately there are no early observations to serve as a ground for this description.

For half a century past many accidental observations respecting this land have been collected, but not a single idea relating to its geology has been made known.

The great genius of Condamine, the zeal of Don George Juan de Ulloa, would certainly not have left us in the dark on this subject, had mineralogy been more cultivated at the time when they wrote.

All that could then be done was to measure and to take levels.

As they were employed on the high cordillera of the Andes, which extends north and south from Zitara, as far as Cape Pilar, and beheld with wonder the immense height of the mountains, they forgot that South America exhibits other cordilleras, which extend east and west parallel to the equator, and which, on account of their height, deserve as much the attention of naturalists as the Carpathians, Caucasus, the Alps of the Valais, and the Pyrenees.

The whole immense tract on the west side of the Andes, which extends obliquely to the coast of Guiana and Brasil, is described as a low plain, exposed to the inundation of the rivers.

As only a few Franciscan missionaries and a few soldiers have been able to penetrate over the cataracts to Rio Negro, the inhabitants of the coast of Caraccas imagine that the immense plains (the Llanos de Calabozo, del Guarico, and de Apure,) which they see to the south, beyond the valleys of Aragua, extend without interruption to the Pampas of Buenos-Ayres, and to the country of the Patagonians; but the extent of these plains is far from being so great; they are not uninterrupted plains, they are rather phenomena of the same kind as those presented by Canada and Yucatan, the island of St. Domingo, the north of Sierra de S. Martha, the province of Barcelona, and the land between Monte-Video and Mendoza, New Holland, the eastern part of Hungary, and the country of Hanover.

They are separated from each other by the cordilleras, and are as far from lying in the same plane as the desarts of Africa, and the steppes of Tartary, which rise by gradations, according to the distance from the sea-coast.

When one considers the irruptions which the North Sea, the Mediterranean, &c. have made into the Old World, the direction of its cordilleras appears not to be very different from that of those in the New World, as most naturalists have asserted.

We are acquainted also with the traces of several high chains of mountains which extend from north to south, and run out from those which extend east and west.

The garnet and micaceous schistus of Norway, Scotland, Wales, Brittany, the province of Gallicia, Alemtego, Cape Bogador, (I have found the same with granite on Teneriff,) the upper part of Guinea, Congo, and the Table Mountain, as also the original mountains of Orenburg, Caucasus, Lebanon, of Abyssinia, and Madagascar, seem at first to have formed nothing else than two large cordilleras parallel to the meridian.

In the New World these cordilleras run parallel to the meridian from Cape Pilar to the north of California beyond Nootka and Prince William's Sound towards the Aleganhey mountains, which were discovered in 1792 by Mr. Stewart, on his journey to the fources of the Missoury, the northern part of the Andes, which is inhabited by Indians nearly as much civilized as the Peruvians were fifteen hundred years ago.

From this cordillera proceed ramifications of the original mountains, which extend from west to east.

With those of North America I am not acquainted, but it appears that some exist in Canada under the latitude of 50°, and 42° north latitude, as in the destroyed continent of the Gulf of Mexico under 19° and 22°; as is proved by the mountains of Cuba and Saint Domingo.

In South America there are three chains of original mountains which run parallel to the equator: the chain of the coast under 9° and 10°; that chain which is in the great cataracts of Autures (in latitude 5° 39') is between latitude 3° and 7°; and that in Maipure in 5° 12' 50", which I therefore call the chain of the cataracts or that of Parime, and the chain of Chequitos under 15° and 20° south latitude.

These chains in the old continent on this side of the Western Ocean can be traced, and it is seen how the original mountains of Fernambouc, Minas, La Bahia, and Janeiro, correspond, under the same latitude, to those of Congo, as the immense plains near the river Amazon lie opposite to the plains of Lower Guinea, the cordillera of the cataracts opposite to those of Upper Guinea, and the Llanos of the Mississippi, since the irruption of the Gulf of Mexico, a property of the sea, opposite to the Desart of Serah.

This view will appear to be less hazarded when one reflects in what manner the old continent has been separated from the new one by the force of the water.

The form of the coasts, and the salient and re-entering angles of America, Africa, and Europe, are a sufficient proof of this catastrophe.

What we call the Atlantic Ocean is nothing else than a valley scooped out by the sea.

The pyramidal form of all the continents, with their summits turned southwards, the great flattening of the earth at the south pole, and other phenomena, observed by Dr. Forster, seem to shew that the influx of the water was from the south.

On the coast of Brasil, from Rio Janeiro to Fernambouc, it found resistance, and taking a direction from the latitude of 50° north towards the north east, where it scooped out the Gulf of Guinea, near Loango Benin and Mine, it was obliged by the mountains of Upper Guinea to direct itself north-west, and separated, to the latitude of 23° north, the coast of Guinea from Mexico and Florida.

The force of the waters was still broken by the cordillera of the United States of America, and once more turned towards the northeast, and seems to have spared less the western coast of Europe than the northern of America.

The least breadth of this channel is at the Brasils and Greenland; but, agreeably to the geographical history of plants and animals, it seems to have been formed at a time when the organic creation had not been properly expanded.

It would be of great importance to geology if a sea voyage were undertaken, at the expence of some government, to examine the rising and depression and the relative situation of the mountains to the salient and re-entering angles of America and Africa.

The same analogy would be found here as is observed in the English Channel, in the Sound, the Straits of Gibraltar, and the Hellespont; small creeks which are as new as the secondary formation of the chalk-rocks of Jura, of Pappenheim, La Mancha, Marseilles, Derbyshire, and Suez, which have all been produced at the same time by precipitation.

Of the three cordilleras of primitive mountains which traverse South America from west to east, the most northern, that of Venezuela, is the highest, but narrowest.

The real chain of the Andes extends from the large plain of Quito, through Popayan and Choco, to the western side of the river Atrato, (or Rio San Juan,) between the valley of Tatabe, in the provinces of Zitara and Biruguete, towards the isthmus, where it forms a mountainous district of not more than two or three hundred toises in height on the bank of the Chagre.

From these Andes arises the cordillera on the coast of Venezuela.

Rows of mountains higher, but forming groups less regular, extend on the east side of the Rio Atrato, under the name of the Sierra de Abibe and the Montes de Cauca, through the high savannahs of Jolu towards Magdalen River and the province of St. Martha.

The cordillera of the coast contracts itself like that of the Gulf of Mexico, approaches nearer to Cape Vela, and then proceeds first from southsouth west to north north east, and then from west to east to the ridge of Paria, or rather to the Punta de la Galera in the Island of Trinidad.

Its greatest height is found at that place where it has the name of Sierra de Nevada de St. Martha, in latitude 10° 2', and of Sierra Nevada de Merida, in latitude 8° 30'; the former is about 5000, the latter 5400 Spanish ells, (varas) or 2350 toises in height.

The Paramo de la Rosa and de Macuchi, and also the mountain of Merida, are continually covered with snow: boiling water, with hydrogenated sulphur, issnes from their sides, and they exceed in height the Peak of Teneriff, and are, perhaps, equal to Mont Blanc, which has been more accurately measured.

These colossal masses and St. Martha stand almost insulated, being surrounded by few high ridges.-- To the west of Santa Fe, or as far as the Sierra of Zuindiu, no snow-clad peaks are seen, and the Sierra Nevada de Merida stands at the edge of the plain of Caraccas, which is scarcely forty toises above the level of the sea.

Mont Blanc, which terminates the high ridge of the Alps, exhibits the same phenomenon.

The altitude of the highest mountains, however, is so very small in proportion to the magnitude of the earth, that it would appear that very small local causes ought to have accumulated more matter in these points.

That part of the cordillera of the coast which lies to the west of Maratayabo- Sees, and joins the Andes, has large valleys extending from north to south, such as that of Magdalena, of Cauca, of Saint George, of Sinu, and Atrato.

They are very long and narrow, but covered with wood.

On the other hand, that part of the cordillera which extends from Merida to Trinidad incloses three valleys, lying east and west, which shew by certain signs, like Bohemia, or the Haslithal of Swisserland, that they have formerly been lakes the water of which has evaporated or run off by opening for itself a passage.

These three valleys are inclosed by the two parallel rows of mountains, into which the cordillera of the coast divides itself, from Cape Vela to Cape Codera; the northern row is a continuation of Saint Martha, the southern a prolongation of Sierra Nevada de Merida.

The first extends through Burburuta, Rincon del Diablo; through the Sierras de Mariara, the mountain Aguasnegras, Monte de Arila, and the Silla de Caracas, to Cape Codera.

The second from three to four miles more to the south, extends through Guigni, La Palma, the high summits of Guairaima, Tiara, Guiripa, and the Savana de Ocumare, as far as the mouths of the Tuy.

These two chains unite with two arms, which run from north to south, like, as it were, dykes, by which these old lakes were confined within their boundaries.

These dykes are, on the west, the mountains of Carora, Tonto, Saint Maria, Saint Philips, and Aroa; they separate the Llanos de Monai from the valleys of Aragua: on the east they are the naked summits of Los Teques, Coquiza, Buena Vista, and the Altos de S. Pedro, by which the valley of Aragua or the sources of the Tuy (for there is only one valley between the bottom of Coquiza, or the Hacienda de Brisenno, to Valencia,) from the valley of Garaccas.

On the east, from Cape Codera, the greater part of the cordillera of the coast of Venezuola was destroyed and laid under water by the great catastrophe which formed the Gulf of Mexico.

The rest of it is distinguished in the high mountain-peaks of the island of Margaretha, (Macanao and the Valle S. Juan,) and in the cordillera of the Isthmus of Araya, which contains the micaceous schistous mountains of Maniguares, Chuparipari, Distilador, Cerro- Grande, the mountain of St. Joseph and of Paria: the remainder I have accurately examined, and found in them the same structure, the same direction, and the same inclination of the strata.

The three hollows, or valleys of Caracas, Aragua, and Monai, are remarkable on this account, that the level of them is above the surface of the sea; they become lower by gradations, and the highest step is the eastern, which may serve as a proof that they were formed at an earlier period than the Llanos, whose declivity proceeds from east to west, like the whole continent of South America. By repeated barometric measurement I found the height of the valleys of Caracas to be 416 toises, of Aragua 212 toises, above the surface of the sea; the Llanos of Monai, the western bason, appears to have an elevation of no more than eighty or one hundred toises.-- The valley of Caracas has once been a lake, which formed for itself an efflux through the Quebrada de Tipe, Catia, and Rio Mamon; the bason of Aragua appears, on the other hand, to have become dry by gradual evaporation; for the remains of the old water (loaded with muriate of lime,) are still seen in the lake of Valencia, which becomes less every year, and discovers islands which are known under the name of Aparecidas.-- The height of the cordillera of the coast is commonly from 600 to 800 toises; the highest peaks, Sierra de Nevada de Merida and the Silla de Caracas, (to which we undertook a laborious journey with our instruments,) are 2350 and 1316 toises in height.

To the west they always become lower, and the height of Cape Codera is only 176 toises.

The Macanao, on the island Margaretha, which I measured trigonometrically, is not more in height than 342 toises; but this speedy depression takes place only in the primitive mountains of the cordillera.

On the eastern coast secondary accumulations of lime rise from Cape Unare to a more considerable height than the gneis and micaceous schistus; these calcareous rocks, which are covered with sandstone of a calcareous base, and which accompany the cordillera of the coast in its southern declivity, are very low on the side towards Cura, but rise in a mass towards the eastern extremity of the continent.

In Bergantin they are 702 toises high, in Coccollard 392, in Cucurucho du Tuminiquiri (the highest summits of the province of Cumana) 976 toises, and the pyramid of the Guacharo rises above 820 toises: from Cape Unare they form a separate ridge of mountains, in which the original ridge totally disappears; they are connected also with the micaceous schistous cordillera of Maniquare and Paria only by the Cerro de Meapire, which, analogous to the branches of Torito and los Teques, which separate the basons of Monai, Aragua, and Caracas, extends north and south from Guacharo and Catouaro, to the mountain Paria, and separates the valley of Cariaco (the driedup bank of the Gulf of Cariaco) from the valley of St. Boniface, which formerly belonged to the Golfo Triste.

It will be seen hereafter, that the accumulation of calcareous formation on the eastern part of the coast of this country seems to have been more exposed to earthquakes; and that the Cerro de Meapire, at the time of the irruption of the Gulf of Cariaco, and the Golfo Triste, prevented the water from converting the land of Araya and the ridge of Paria into an island.

The declivity of the cordillera of the coast of Venezuela is gentler towards the south than towards the north, which is particularly striking when one descends from the heights of Guigue, through St. Juan, Parapara, and Ortiz, towards the Mera de Paja, which belongs to the great Llano de Calabozo.

The northern declivity is every where very steep, and there is scarcely found, Mont Blanc excepted, above Courmayeur, a more frightful precipice than the perpendicular wall of Silla de Caracas, beyond Caravalledo, which rises to the height of 1300 toises.

An accurate measurement of this wall of rock was of great importance to navigators, as they could find its distance from the coast only by taking the angle of its elevation: its longitude, therefore, of 60° 37' 32" west from Paris will enable them to discover it.

The phenomenon of a more gentle declivity towards the south seems to contradict the observations made in other cordilleras of the earth, as it is asserted that they all decline more abruptly towards the south and west.

This contradiction, however, is only apparent; as the northern part of the cordillera, during the great catastrophe which produced the Gulf of of Mexico, was torn away by the force of the water; and therefore the northern declivity might at that time be gentler than the southern.

If the form of the coast be considered, it appears to be pretty regularly indented.

The headlands of Tres Puntas, Codera, S. Roman, and Chichibacoa, on the west, from Cabo de la Vela, form a row of promontories, the western of which runs more to the north than the eastern.

To the windward of each of these capes a creek has been formed; and one cannot help seeing, in this singular formation, the action of the tropical currents, which may be called the currents of the earth's rotation; an action which shews itself also in the direction of the coast from Cuba, St. Domingo, Porto Rico, Yucatan, and Honduras, as in the series of the Windward Islands, Grenada, Orchila, Rocca, Aves, Buenos-Ayres, Curacoa, and Aruba, the ruins of the cordillera from Cape Chichibacoa, which are all parallel to the equator.

It was this headland of Chichibacoa, notwithstanding its inconsiderable height, which, by its resistance to the influx, preserved the kingdom of New Grenada from losing so much land as the general government of Caracas.

The second original cordillera of South America, which I have called the cordillera of the Cataracts of Orinoco, is yet very little known.

During the journey which we made on the Black River, to the borders of the Great Bara, we travelled more than two hundred leagues, first from north to south, from Cerro de Uruana to Atabapo and Tuamini; then from west to east, from the mouths of the Ventuari to Vulcan de Duida, which I have found to be in latitude 3° 13' 26", and longitude 60° 34' 7" west from Paris.

Since the journey of Messrs. Ituriaga and Solano, a passage over these cordilleras, which may be called also Parima or Dorado, (Golden) a name which has occasioned so much missortune in America, and so much ridicule in Europe, has been possible; but as all the European settlements on the Alto Orinoco, and the Rio Negro, (Black River,) contain at this time no more than four hundred Indian families; and as the way from Esmeralde to Erevato and Caura has been totally lost, our researches in a land so little civilized presented more difficulties than Condamine experienced during his tedious navigation on the river Amazon, the banks of which for many years have been inhabited.

The cordillera of the Cataracts, or of Parima, separates itself from the Andes of Quito and Popayan, in the longitude of from 3° to 6°. It extends from west to east, from Paramo de Tuquillo and St. Martin, or the sources of the Guaviare, the theatre of the gallant deeds of Philip de Urre, and the old residence of the Orneguas, through Morocote, Piramena, and Macuco, stretching through the country of the Indians of Guajibos, Sagi, Dagueres, and Poigraves, according to the direction of the great rivers Meta, Vichada, Zama, Guaviere, and Ymerida, in the longitude of 70° west from Paris, between the high summits of Uniama and Cunavami.

They form the Raudals of Atures and Maypure, tremendous waterfalls, which afford the only passage by which one can penetrate into the interior of the land in the valley of the River Amazons.

These Cordilleras of the Cataracts rise from the longitude of 70°, and spread out in such a manner that they comprehend the whole immense tract of country between the rivers Caura, Erevato, Cavony, Paraguamusi, Ventuari, Jao, Padamo, and Manariche, and then ascend south towards the sources of the Pasimona, Cachevaynris, and Cababury, towards the forests, where the Portugueze, penetrating into the Spanish districts, collect the best sarsaparilla known (Smilax Sarsaparilla.

Linn.).

In this district the cordilleras of the Cataracts are above one hundred and twenty miles in breadth.

Their continuation more towards the east, between the longitude of 68° and 60° west from Paris, is little known.

I proceeded with astronomical instruments only, as far as Rio Guapo, which discharges itself into the Orinoco, opposite the Cerro de la Cauclilla, in longitude 68° 33' west from Paris.

The Indians of Catarapeni and Maquiritares, who reside in the small mission of Esmeralde, came fifteen miles further east over the mountains Guanaja and Yamariquin to the Canno Chiguire; but neither the Europeans, nor Indians with whom Europeans have had any intercourse, are acquainted with this source of the Orinoco, which is here called Canno Paragua, and is scarcely 150 or 200 toises in breadth, whereas at Boca de Apure, in latitude 7° 32' 20", it is 4632 toises, as I myself found.

The wildness of the Indians of Guaicas, who are only four feet in height, but who are a very white and warlike people, and particularly the savage state of the Guajaribos, greater men-eaters than any of the other nations which we visited, prevent any one from penetrating over the small cataracts (Raudal de Guajaribos,) east from Chiguire, unless a military expedition were undertaken on purpose.

But by the wonderful journey undertaken by D. Antonio Santos, who married Onotho, and who dressed sometimes as a Carib, and sometimes as a Macacy, whose languages he spoke, from Orinoco (the mouth of the Rio Caronis) to the small lake Parima and the river Amazon, we have obtained information respecting the continuation of the cordillera of the Cataracts.

Under the latitude of from 4° to 5° and longitude 63°, it becomes so narrow that it is scarcely sixty miles in breadth.

It assumes here the name of Cerrania de Quimiropaca and Pacaraimo, and forms a chain of not very high ridges, by which the waters were divided.

The water of the northern declivity, the Nocapray, Paraguamuci, Benamo, and Mazurini, flow towards the Orinoco and Rio Esquibo; the waters of the southern, the Rio Curuicana, Parime, Madari, and Mao, pour themselves into the River Amazon.

Some degrees further towards the east, the cordillera again extends in breadth as it ascends southwards towards the Canno Parara along the Mao.

It is here that the Dutch give to the Cerro d'Ucuamo the magnificent name of the Gold Mountain, or Dorado, because it consists of a very shining micaceous schistus, a fossil which has brought into celebrity the small island of Ypamucena in the Lake of Parima.