Sketch of a Geological Delineation of South America. By F. A.

Von Humboldt .

This sketch is an extract from a paper transmitted by M.

Von Humboldt from South America, together with a geological collection, to the directors of the cabinet of natural history at Madrid.

It was sent also by M.

Von Humboldt to Delametherie, and inserted by him in the Journal de Physique, vol. 53. p. 30.

Since I sent to Madrid the two first sketches of a geological delineation of South America, from the Caraccas and Nueva Valencia, I have travelled 1200 miles, and described a square between Caribe, Portocabello, Pimichin, and Esmeralda, a space comprehending above 59000 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 (see Plate IX.); 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 Caracas 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 St. 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 deserts 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 sources 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 Gulph 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 Gulph 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 phænomena, observed by Dr. Forster, seem to show that the influx of the water was from the south.

On the coast of Brasil, from Rio Janiero 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 Minc, 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 north-east, 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 expense 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 the 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 Tatabé, 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 Abibé 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 Gulph of Mexico, approaches nearer to Cape Vela, and then proceeds first from south-south-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) issues 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 Fé, 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 Caracas, which is scarcely forty toises above the level of the sea.

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

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 Maracaybo-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 show 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 Guigui, 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, Torito , 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 Caracas.

On the east from Cape Codera the greater part of the cordillera of the coast of Venezuela was destroyed and laid under water by the great catastrophe which formed the Gulph 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 80 or 100 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 dried up bank of the Gulph 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 Gulph 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 frighful 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 Gulph 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 shows 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, Curaçoa, 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 200 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 misfortune 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 400 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, Guaviare, 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 Maypuré, 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, Cachevayneris, and Cababury, towards the forests, where the Portugueze, penetrating into the Spanish district, collect the best sarsaparilla known (Smilax Sarsaparilla, Linn.

).

In this district the cordilleras of the Cataracts are above 120 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 Apuré, 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 60 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 Cururicana, 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.

On the east from Rio Esquibo, or on the other side of the land of the Aturajo Indians the cordillera turns southeast as it unites with the garnet mountains of the Dutch and French Guiana, which are inhabited by a mixture of Negroes and Caribs, and give an origin to the rivers Berbice, Surinam, Marony, Aprouague, and Oyapock.

The last mentioned ridge of mountains extends very much: its gneis appears at Baxo Orinoco, in latitude 8° 20′, between the mouths of the Upata and Acquire, and in latitude 2° 14′ on the north side of the river Amazon, in the mountains of Fripoupon and Maya.

Such is the form of the great cordilleras of the Cataracts, which are inhabited by a great number of uncivilized savages, little known to the Europeans. I must here observe, that in this description I have followed my own observations only, and the notices we obtained from the Indians, as also the observations of D. Antonio Santos, and the companions of his journey, who dictated to their friends.

The maps of this part of the continent are entirely false, and the map added to the history of the Evircoco by P. Caulin, a work in other respects meritorious, is by our last observations some degrees more wrong in longitude and latitude than the map published thirty years before by d’Anville.

All the Indian names in it also are mutilated, and mountains and rivers are delineated where none exist; a defect the more pardonable as the author was never beyond the waterfalls of Orinoco, nor at the Rio Negro.

[To be continued.]

Sketch of a Geological Delineation of South America. By F. A.

Von Humboldt.

[Continued from our last volume, p. 357.]

The cordillera of Parima never reaches to the same height as the Sierra Nevada in the province of Caraccas, which is 2350 toises.

Their highest summit seems to be the Cerro de la Esmeralda, or the mountain Duida, which, by trigonometrical measurement, I found to be 1323 toises above the surface of the sea, which is the height also of the Canigou.

This mountain is situated in a delightful plain covered with ananas and palms:

the monstrous mass which it exhibits towards the Mission and the rivers Canu-canuma and Tamatama, and the flames it vomits up towards the end of the rainy season, give it a romantic and majestic appearance.

No Indian is able to clamber up to the top of this mountain and the rocks of its summit without a week’s labour, because the luxuriance of vegetation in this climate impedes the progress of travelling.

Next to the Duida, the Maraguaca, more towards the east of the river Simirimóni, and the high cordillera of Cunarami and Calitamini, which at Maypuré and St. Barbara is known under the false name of Sipapo, are the highest summits of the chain; they are from 1000 to 1100 toises in height.

The common height of the cordillera, however, does not exceed 600 toises, and sometimes it is less, as the part situated between the left bank of the Cassiguiaré, an arm of the Orinoco which connects together the Rio Negro and the river Amazon, and the sources of the cataracts and Piramena between Carichana and Morocote, is destroyed, and still exhibits insulated rocks rising from the ground.

The cause of this destruction seems to have been an eruption of water from the bason of the Amazon river towards the bason of Calabozo and Baxo-orinoco, which differ in height about 160 toises.

The geological chart of this district which I have constructed represents an immense valley which unites the Llanos of the Rio Negro, Cassiguiaré, and Amazon, with those of the province of Caraccas, Barcelona, and Cumana; a valley which sinks down towards the north, and is intersected by a large series of single rocks which show the direction of the old cordillera on the banks of the Guaviare and Nuta in the province of Cassemora.

The eastern extremity of this valley is the lowest part of it, and therefore the remains of the water of the Orinoco cut out for itself a bed in this place.

This cordillera has two remarkable properties.

In the first place, as has been remarked in other ridges, the southern declivity is much steeper than the northern: the high summits of Caravami, Jao, of the volcano of Duida, Maraguaca, &c., all lie towards the south, and are there cut into perpendicular precipices.

In the second place, this cordillera does not seem to contain a single rock of alluvial mountains, and consequently has borrowed nothing from the organized kingdom.

On our passage over this ridge we observed nothing but granite, gnieis, micaceous schist, and hornblend schist; nowhere a covering of sand-stone or alluvial chalk, which on the cordillera of Venezuela on the coast rises to the height of 976 toises above the level of the sea.

Had the proximity of the equator and the rotation of the earth any influence on this phænomenon?

The third chain of original mountains, the cordillera of Chiquitos, is known only from the accounts of some persons who have resided at Buenos-Ayres and travelled through the Pampas. It unites the Andes of Peru and Chili with the ridges of Brasil and Paraguay as it stretches from La Paz, Potosi, and Tucuman, through the provinces of Maxos, Chiquitos, and Chaco, towards the government of the Mines and of St. Paul in Brasil.

Their highest summits seem to be situated between the latitude of 15° and 20° south, as the streams between the rivers Amazon and La Plata divide themselves at that height.

Between the three cordilleras, the direction of which we have hitherto followed, lie three broad and deep valleys.

1st, The valley between the south side of the cordillera of Venezuela, on the coast, and the cordillera of the Cataracts, or the valley of Orinoco and Apuré, between latitude 8° and 10°.

2d, The valley of the rivers Negro and Amazon, bordered by the Parima ridge and the cordillera of Chiquitos, between latitude 3° north and 10° south. 3d, The valley of Pampas of Buenos-Ayres, which extends from Saint Cruz of Sierra to Cape Virgin, between 19° and 52° south latitude.

The first and second valley are in some measure united by the destruction of a part of the Parima cordillera.

I do not know whether this be the case also with the Pampas and valley of the Amazon; it, however, appears that it is not, though the Llanos of Monso form a sort of canal which descends from north-west to south-east.

All these immense valleys or plains are entirely open towards the east, as they run out into a low sandy coast: towards the west they are shut by the chain of the high Andes.

There are some creeks (anses) which proceed from east to west in the direction of the tropical current, and on that account extend further into the land the broader the continent is.

The valleys of Apuré and Orinoco are closed by the ridge which extends from Pampelona to Merida in longitude 73°, and the valley of Pampas in longitude 70°: they both fall together a little towards the east, and seem to be covered by one and the same formation of alluvial strata.

Tralles says, that in Swisserland there is more reason to wonder at the depth of the lakes than at the height of the mountains: I will venture to make a similar observation in regard to the Llanos or plains of South America.

How astonishing it is to see a continent which in its interior parts several hundred miles from the coast, and in the neighbourhood of mountains 3000 toises in height, is elevated scarcely fifty toises above the surface of the sea!

If the flux in these places should rise to as great a height as at St.

Malo and Bristol, and if more motion should be communicated to the ocean by earthquakes, the greater part of these valleys would be laid under water.

The highest Llano which I have measured is that between the rivers Ymirida, Temi, Pimichia, Cassiguiaré, and Guiainia (Rio Negro); it is 180 toises in height; but it sinks down towards Atures in the north, as towards the river Amazon in the south.

The valley of Orinoco and Apuré is still much lower than that of Cassiguiare and Calabozo in the middle of the Llano where I made observations, in latitude 8° 56′ 56″ and longitude 70° 9′ west from Paris.

At Angostura, the capital of Guyana, latitude 8° 8′ 24″, longitude 66°, it is only 33 toises, and eighty miles from the coast scarcely eight toises above the level of the sea.

The plains of Lombardy, in Europe, have the greatest resemblance to the Llanos on account of their small elevation.

Pavia is only 34, and Cremona 24 toises in height; the other plains of Europe have a much greater elevation.

In Saxony and Lower Silesia the plains are only from 87 to 120 toises in height; those of Bavaria and Swabia are from 230 to 250. The declivity of the Llanos of America is so gentle, their inequalities are so imperceptible, that no large river flows to either side.

The Orinoco appears in the longitude of about 70°, as if about to discharge itself in the sea towards Portobello; but at Cabrouta it turns to the east without the least obstacle being discovered either there or at St.

Fernando de Atabapo, in latitude 7° 55′ 8″, to oppose its course.

In the large valley of Rio Negro, and of the Amazon river, is a tract of land, in 2° or 3° north latitude, of not less than 1600 square miles, which is bordered by the large rivers Atabasso, Cassiguiaré, Guiainia, and Orinoco, and represents a parallelogram, in which the water flows on the four opposite sides in opposite directions.

In regard to the Orinoco, I found a fall of 151 toises in the distance of 70 miles from the mouth of Guaviare to the Apuré; but from the capital to the sea not more than eight toises.

La Condamine observed the same thing in regard to the river Amazon, from the narrow pass of Paucis to Para, where it runs through a district of 240 miles, but falls not more than 14 toises.

It is not improbable that there might have been on the north side of the cordillera of the coast of Venezuela a plain as much lower than the plain of Orinoco as the plain of Rio Negro is higher than that of Orinoco, and on this account the former plain was covered by the water of the bay.

The two Llanos or plains which lie at the opposite extremities of America exhibit a striking difference from that which lies between them, namely, the vale of the river Amazon.

The latter is covered by so impenetrable forests that rivers alone can force a passage through them, and that scarcely any other animals but such as frequent trees can live in that district; so much is vegetation favoured by the continual rains under the equator.

The case is quite different with the plains of Orinoco and Pampas; they are level valleys covered with herbs, and savannahs which contain only a few scattered palm-trees.

The same heat, the same want of water, and the same phænomena of refraction, that is to say, the inverted image of objects seen floating in the atmosphere, are observed here as in the deserts ofAfricaand Arabia.

But plains so perfect are nowhere else to be found; for the Mesa de Pavone and the Mesa de Guanipa in 800 square miles contain no eminence of eight or ten inches in height.

The plains of Lower Hungary, on the west of Presburgh, have the greatest resemblance to them; for the flat land of La Mancha, Champagne, Westphalia, Brandenburgh, and Poland, is hilly when compared with the Llanos of South America.

Nothing but a long stagnation of water could have produced so horizontal a bottom.

Traces of old cities are found here, but seldom are any seen which rise like castles (La Piedra Guanan, longitude 69° 3′, latitude 1° 59′ 48″) in the Llano of Cassiguiaré and of Rio Negro.

But from St.

Borja to the mouth of the Black river Condamine observed no eminence; and the Llano of Orinoco is also without islands.

As the Morros of San Juan belong to the southern declivity of the cordillera of Venezuola, an impetuous current of water must have swept every thing along with it; and the present sea presents large spaces without islands: instead of islands there are in the Llanos whole uninterrupted portions of from 200 to 300 square miles of surface which rise from two to five feet above the plain, and which are called mesas or bancos; which is as much as to say, that they were shoals or sand-banks in the antient sea. I must here observe, that the middle of the plain of Orinoco is the most beautiful and levellest part of it.

The bottom of this immense bason rises up and becomes unequal at the edge; the plains therefore which one traverses between Guyana and Barcelona are less perfect and level than those of Calabozo and Uritucu.

This remarkable difference which we found between the cordillera of Venezuola and that of the Cataracts, which is that the latter consist of alluvial mountains entirely bare, is observed between the northern Llano of the Orinoco and that of the Rio Negro and river Amazon.

In the former, the original mountains are every where covered with compact limestone, gypsum, and sandstone: in the latter the granite every where appears.

The more one approaches the equator the thinner is the stratum of sand which covers the crust of earth on the original mountains: in a land where vegetation is so luxuriant, there is seen in the middle of forests spaces of 40,000 square toises scarcely covered with a few lichens, and which do not rise two inches above the rest of the surface.

Will the same be discovered in Africa?

for it is only in America and Africa that there is land under the equator.

Having taken a view of the direction of the mountains and valleys, or the form of the inequalities of the earth, let us now turn our attention to objects of more importance which have been less examined, namely, the rising and falling of the strata of the original mountains which form this part of the earth I have traversed.

I have been convinced since 1792 that the rising of the original mountains follows a general law, and that, making allowance for those inequalities which may have been produced by trifling local causes, and particularly veins and strata in mines, or by very old valleys, the stratified coarse-grained granite, the foliated granite, and particularly the micaceous schist and argillaceous schist, rise in the league 3 [Formel] by the miner’s compass, as they form with the meridian of the place an angle of 52 [Formel] °.

The falling of the strata is towards the northwest; that is to say, they fall parallel with a body that might be thrown in the same direction, or the aperture of the angle of inclination (less than 90°) which it makes with the earth’s axis stands towards the north-east.

The rising is more constant than the falling, especially in the simple mountains (argillaceous schist, hornblend schist), or in the compound mountains with fewer crystallized grains, such as the micaceous schist.

In granite (it is, however, found very regularly stratified rising in the league 3 — 4, and falling towards the north on the Schneekopfe, the Ochsenkopfe, the Siebengebirge, and the Pyrenees,) and in the gnieis the attraction of the crystallized mixed parts to each other seems to have prevented the regular stratification; therefore more coincidence is found among the micaceous and argillaceous schist, and these first led me to the idea of the law of rising during my tour to the Fichtelberg and the Thuringian forest.

Since that time I have examined with great care the angle of the strata of other original mountains in other parts of Germany, in Swisserland, Italy, the southern parts of France, and the Pyrenees, and lately in Gallicia. Mr. Freiesleben, whose labours have been of so much service to geology, assisted me in this examination; and we were astonished at the uniformity in the rising and falling of the mountains which we found at each step on one of the highest cordilleras of the earth, the Alps of Savoy, the Valais, and the Milanese.

An examination of this phænomenon, and of the identity of the strata, was one of the principal objects when I undertook a voyage to America.

A measurement of the angles which I have hitherto made on the cordillera of Venezuola and Parima gave again the result of my observations in Europe in the chain of the micaceous schist mountains of Cavaralleda as far as Rio Mamon; on the Silla de Caracas at the height of 1000 toises; of the Rincon del Diablo, on mount Guigue; in the islands in the beautiful lake of Valencia, which has almost the same elevation as the lake of Geneva, at the boundaries of the isthmus of Maniguaré and Chupariparu; on the hornblend schist which appears uncovered in the streets of the capital of Guyana, and also in the Cataracts, and on the stratified granite at the foot of the Duida.

Every where the strata form an angle of 50° with the meridian (in the league 3 — 4 by the Saxon compass) as they rise from the north-east to south-west, and fall about from 60 to 80 towards the north-west.

This great coincidence in the old and new world must excite serious considerations.

It exhibits a very important geological fact.

After so many observations which I have made in places so far distant from each other, it can no longer be believed that the rising of the strata follows the direction of the cordillera, and that the falling follows the declivity of the mountains.

The profile of many of the mountains, particularly a section of the mountains, such as that of Genoa through the Bochetta, and of St. Gothard as far as Franconia in Germany, which I intend to publish at a proper time, proves exactly the contrary.

The rising and declivity of the cordillera, the form of the small inequalities of the earth, seem to be newer phænomena.

A stream might scoop out a valley in this or in that direction; might tear asunder a part of the cordillera, and give it apparently one direction or another.

The strata of the original mountains appear, amidst all these angles of rising and falling observed at present, to have existed before these changes at the surface of the earth.

They are the same at the summit of the Alps, and in the mines into which we descend.

When one travels for 15 miles over strata of argillaceous schist, which are inclined parallel to each other, at an angle of 70° towards the north-west, one can no longer believe that they are deranged strata, which once stood horizontal.

We must suppose mountains that were once 15 miles in height, and that the whole mass had an uniform fall, and then reflect on the space which such a mass would occupy: and one must remember the strata on the heights of Genoa, or on the heights of Bochetta, or on St. Maurice, which are exactly parallel; and on the strata of the Fichtelberg of Gallicia, the Silla de Caracas of Robolo on the isthmus of Araya of Cassiguiare, in the neighbourhood of the equator.

One must allow that this coincidence gives evidence of a cause which has acted at a very early period, and in a general manner; a cause which must have arisen from the first attraction by which matter was forced together to form a spherical planet.

This grand cause does not exclude local causes, by which individual smaller parts of matter were determined to arrange themselves in this or in that manner, according to the laws of crystallization.

Delametherie has made an ingenious remark on this subject: he shows the influence of a large mountain (as a small nucleus) on the neighbouring small mountains.

One must not forget that, besides the general attraction towards the centre, all matters exercise a mutual attraction on each other.

The crust of the earth, for I will venture to speak only of this part, must be the result of an immense action of powers of attraction of affinities, which determined, put in equilibrium, and modified each other. M.

Klugel thought he found, by calculation, that the great flattening of the earth must be on the west side of the north pole.

Has the axis of rotation been changed?

What will be the inclination of the strata in the southern hemisphere?

We are not acquainted with the cause; let us rather continue to examine the phænomena.

This falling of the strata of the original mountains in the cordillera of Venezuola has a great and melancholy influence on the fertility of the provinces of Caracas, Cumana, and Barcelona; the water which filtres through at the summit of the mountain flows down according to the direction of the strata, and for this reason there is great want of water in the whole large district which lies on the south side of the cordillera, and therefore so many springs and small streams burst forth on the northern declivity, which, by this great quantity of moisture, and the superabundance of wood, which shelters it almost the whole day from the sun’s rays, is rendered as unhealthful as it is fruitful.

The alluvial mountains which I have hitherto observed are almost under the same circumstances as in Europe.

The oldest seem to have experienced the action of the same causes which determined the strata of the original mountains, as they rise in the league 3—4, or as the seamen express it, N. 50 E. They often fall towards the south-east, as in the Alps of Bern, the Valais, Tyrol, and Steyermark; but the greater part of them, and particularly the newest, which where I have been are the most numerous, follow no certain law; their strata often lie horizontally, or rise towards the edge of the large dried-up basons, which in America are called Llanos, and inAfricaDeserts.

La Condamine says that in Peru and Quito he observed no petrifactions.

The cordillera of Quito, however, is not like that of Parima, naked granite, for at Cuença, and on the south side, there is gypsum and alluvial chalk.

Buffon dwells much, in his Epoques de la Nature, on the question whether South America contains petrifactions?

I have found an immense quantity of them in calcareous alluvial sandstone which covers the northern and southern declivity of the coast of Venezuola, from the summit of St. Bernandin, and the Altos de Conoma, to the Cerro de Meapiré, or the headland of Puria and Trinidad.

The same stratum is found also in Tobago, Guadaloupe, and St. Domingo.

An immense quantity of sea and land shells, which in Europe are seldom found mixed together, cellulariæ, madrepores, cerallines, and astroites, are found interspersed in this sandstone.

The shells themselves are half broken: whole rocks consist merely of such remains reduced to powder.

My fellow-traveller, Bonpland, discovered in them shells of the genus Pinna, Venus, and Ostrea, of which living specimens are still met with on that coast; an observation of great importance to geology.

Every thing shows that this stratum, which I have seen only at the distance of nine or ten miles from the present coast, is of very modern origin, and that the fluid in which it was produced had been in a state of violent motion.

The petrified shells in a much older stratum of compact limestone are scarcer and much differently stratified: they are anomia, terebratulites, &c. placed together in families, and in such a manner that it is seen that they have lived (as those of Mount Salive, the Heinberg near Göttingen, of Jena, and Geneva) on the spot where they are now found petrified.

They are not interspersed throughout the whole mass of the limestone; they are only peculiar to certain strata.

Many rocks may be examined without finding any of these petrifactions; but where found they are in great quantity, and present themselves chiefly on great heights; peculiarities which they have in common with the shells found in the limestone of the high Alps of Swisserland and Salzburg, which is identic with the hardened marl of Thuringia, a limestone which lies above the very old sandstone.

I must observe also, that, besides the new sandstone stratum with a calcareous base, of which I have already spoken, the petrifactions do not often occur; and I was particularly astonished to find no single belemnites or ammonites which are so common in all the mountains of Europe.

The Llano of Orinoco, and that even of Rio Negro, are covered with a coarse grained breccia (nagelfluhe) which contains no petrified shells, and perhaps covers the other alluvial strata with petrifactions.

But this breccia contains on the other hand petrified trunks of trees, which are sometimes found of the length of a toise, and of the diameter of two feet.

They seem to belong to a kind of Malphigia.

The sandstone which contains all kinds of marine animals (the quarry of Punta del Barrigon near Araya is of this sort) never exceeds the height of from 30 to 40 toises.

In several places it forms the bottom of the Gulph of Mexico (Cabo Blanco, Punta Araya).

In the compact limestone I never saw petrified shells above the height of 800 toises; but other very new testimonies prove the residence of the water at much greater heights.

Slate found on the Silla de Caracas, at the height of 1130 toises, proves that the water once, as on the Bonhomme in Savoy, formed this aperture between the two peaks or pyramids of the Avila, an aperture which is much older than the five counted in the cordillera of the coast, namely, those of Rio Neveri, Unare, Tuy, Mamon, and Guyaca.

Among the mountains of the province of Cumana, there are very singular valleys of a perfect circular form, which seem to be dried up lakes.

Of this kind are the valleys of Cumanacoa and St. Augustine, 507 toises in depth, which are celebrated for the refreshing coolness which travellers experience in them.

When the modern action of water is considered, two opposite effects are observed: one recollects a very distant epoch, when the irruption of the sea formed the Gulph of Cariaco and the Golfo Triste; separated Trinidad and Margaretha from the main land, and convulsed the coast of Mochima and Santa Fé, where the islands of la Boracha, Picua, and Caracas, form a heap of ruins.

The sea then attacked the land; but the contest did not long continue: the ocean again begins to draw back.

The islands Coche and Cuagua are shoals which emerged from the water; the large plain of Salado, lying in Cumana, belongs to the Bay of Cariaco, and is only 5 [Formel] toises above the level of the sea.

The hill on which the castle of St. Antonio is situated was an island in this gulph, as an arm of the sea passed to the north of Tatoraqual through the Charas towards Punta Delegada, as is proved by a multitude of unaltered shells.

It is observed here and at Barcelona that the sea is daily retiring: in the harbour of Barcelona it has lost in 20 years above 900 toises.

Is this decrease of the sea in the Gulph of Mexico general, or is it the case here, as in the Mediterranean Sea, that it gains in one point and loses in another?

This retreat of the sea must not be confounded with another real phænomenon easy to be explained, namely, the decrease of fresh water, of rain, and of the rivers in this continent.

The Orinoco, as we see it at present, is no longer the shadow of what it was 1000 years ago, according to the evidence of the traces which the water has left on both banks at the height of 70 or 80 toises.

These traces have long attracted the notice of learned Europeans who have seen the Barraguan, the Cueva de Ataruipe (the burying place of the Atures Indians, who formed a kind of mummies), the Cerro Cuma, the Daminari, the Keri, Oco, and Ouivitari, the bottom of which at present is scarcely covered by the foam of the Cataracts of Maypuré.

These traces remind the Indians of a great inundation, during which many persons saved themselves on rafts of Agave, and afterwards cut out inscriptions and hieroglyphics, with which the granite of Urnana, of Incaramada, and the banks of Cassiquiaré, are seen covered, but of which no one at present has the key.

This tradition, common among the Indians of Erovato and of Parima, shows great analogy with the mythology of the antients.

People think they read the history of Deucalion, and Pauw would find the remembrance of this flood not uninteresting.

[To be concluded in our next.]

Sketch of a Geological Delineation of South America. By F. A.

Von Humboldt.

[Concluded from p. 36.]

Having already given a cursory view of the general appearance which the mountains of South America exhibit to the eye of the geologist, I shall now enumerate the different kinds of mountains which I have hitherto discovered in that country, beginning with the oldest.

I. Primitive Mountains.

Granite.—The whole cordillera of Parima, and particularly the neighbourhood of the volcanoes of Duida and Marcielago, consist of granite, which does not form a transition into gneiss.

In the cordillera of the coast it is almost every where covered and mixed with gneiss and micaceous schist.

I saw it disposed in strata of from two to three feet in thickness, exceedingly regular, declining from three to four per league, towards the north-west between Valencia and Portocabello. I found it on the Rincon del Diablo south-east from Portocabello, with large and beautiful crystals of feldspar an inch and a half in diameter, like the large grained granite on the high summits of the Schneegebirg and the Fichtelberg, those of Scotland and Chamouni. It is here split into regular prisms; and I saw it on Calavera du Cerro de Mariana beyond Cura, and on the Silla de Caracas, in this prismatic form, which the learned mineralogist M. Karsten observed on the Schneekoppe in Silesia.

The northern part of Germany, and the lands on the Baltic in Europe, but not the plain to the south of the Fichtelberg in Swabia and Bavaria, are full of monstrous blocks of granite which have rolled down from the heights.

In neither of the llanos of South America, that of Orinoco, and that of the Amazon river, did we find any such masses, and no fragments of primitive mountains.

The granite mountains of Los Mariches near Caracas, and those of Torrito between Valencia and St. Carlos, and that of Sierra Neveda de Merida, contain, like that of St. Gothard, fissures which are covered with very beautiful and large rock crystals.

The granite is covered with gneiss and micaceous schist, particularly on the cordillera of the coast of Venezuela.

Gneiss is abundant in particular from Cape Chichibocoa to Cape Codera in the Tequez, Cocuiza, and the mountain Guigue , as well as in the islands of the Lake of Valencia, where I found (on Cape Blanc, opposite to Guacara,) blackish quartz in the gneiss which passes into Lydian stone, or rather into the schistous state of Werner.

The Macanao on Margaret’s island, and the whole cordillera on the isthmus of Cariaco, is nothing else than micaceous schist full of red garnets; and at Maniquarez it is combined with a little cyanite.

Green garnets are intermixed with the gneiss of the mountain Avila.

In the gneiss of the rock Calamicari in Cassiquiare, and in the granite of Las Trincheras near Valencia, I saw round masses, from three to four inches in diameter, interspersed, which consisted of finer grained granite, yellow feldspar, a great deal of quartz, and scarcely any mica.

Is this old granite contained in some of later formation, or are these masses, which have the appearance of accumulations, merely the effect of attraction, which here and there made the particles to approach nearer to each other, but at the same time that the whole mountain was formed?

This phænomenon of one kind of granite interspersed in the other is observed also in Silesia, at Wunsiedel, on the Fichtelberg, in Chamouni, on St. Bernard, on the Escurial, and in Galicia.

Nature is uniform in her natural productions, even to the small variations in proportions.

The micaceous schist passes into talc schist in the cordillera of the coast, on the mountain Capaya, and on the Quebrada Secca, in the valley del Tuy.

In the cordillera of Parima talc is found in very large shining masses, and this has contributed so much to the celebrity of the Dorado, or Cerro Ucucuamo, between the river Esquivo and Mao, in the island Pumacena.

The bright fiery appearance exhibited sometimes by the truncated pyramids of the large Cerro Calitamini, near Cunavami, at sun-setting, seems also to proceed from a stratum of talcy schist cut perpendicularly towards the west.

Small idols of nephrite, which I saw brought from Erovato, show that to the south of Raudal de Mura there are nephrite rocks in gneiss like those I found at the bottom of St. Gothard, near Ursern.

This formation was repeated by nature in the land of the Tupinambaros Indians.

La Condamine discovered this variation of the hard nephrite, which is known under the name of the Amazon stone.

The granite, gneiss, and micaceous schist, contain here, as in Europe, strata of chlorite schist arranged under each other in the sea at Cape Blanc west from Guayra.

Very pure and beautiful hornblend schist is found in the streets of Guyana; and, still more south, in the cordillera of Parima, feldspar effloresces into porcelain earth in the Silla de Caracas; strata of quartz, with magnetic iron-stone, is found at the sources of the Cutuche, near Caracas; grained foliaceous, primitive limestone, without tremolite, but with a great deal of sulphureous pyrites and sparry iron-stone, on the Quebrada de Topo on the road from Caracas to Guayra.

This limestone is entirely wanting in the cordillera of Parima, where it has been sought for many years.

Zeichen schist, a kind of carbonaceous iron, and pretty pure graphite, are found in the Quebrada de Tocume near Chacao, in the Quebrada Secca near Tuy, and north from the Laguna Chica; on the difficult road which leads across the isthmus of Cariaco to Chiparipara, there are found veins of quartz, which contain auriferous sulphureous pyrites and antimony, native gold, gray silver ore, mountain blue, malachite, &c.

The copper ore of Aroa is the only kind here taken from the earth: sixty or seventy slaves obtain yearly 1500 quintals at most of refined copper.

The quintal is sold for twelve piastres.

The valley in which this ore is dug up is less unhealthful than the valleys near the sea where the Indians wash gold; namely, Urama, Maron, and Alpagoton, where the air appears to be poisonous, as is the case in the fertile valley of Cararinas between Nirgua and Rio Jaracuy.

The gold is dispersed throughout the whole province, particularly in the strata of quartz at Baruta, Catia, Guigue , Quebrada del Oro near Tuy, and on the Cerro de Chacao, and Real de Santa Barbara near St.

John, where I found barytic spar, the only instance I ever met with in this country.

All the rivers of the province of Characas, wash down gold.

It however does not thence follow that this province is rich, and contains veins of gold not yet discovered: the gold may be interspersed in whole masses of granite; and I am acquainted with no high granite cordillera, either here or in Europe, the rivers of which do not wash down gold.

The Cerro Duida of Esmeralda in Dorado, the Quebrada du Tigre near Encaramada, and the Cerros de Amoco, the Real de S.

Barbaro near St. John, the Quebrada de Catia, the alum ore of Chuparuparu, some traces of iron ore in the llano of St. Sebastian, and particularly the Aroa abundant in copper, seem to call for the industry of the miners.

Argillaceous schist is very scarce: it covers the micaceous schist on the southern declivity of Venezuela, in the neighbourhood of the Llanos, in the Quebradas de Malparo, and Piedra Azul: there is blue argillaceous schist, with veins of quartz, on the isthmus of Cariaco, near Chuparuparu, in the Distillador Arroyo du Robola, and also on Macanao.

In the four last-mentioned places there are found in the argillaceous schist alum and vitriolic schist, in strata of two or three feet in thickness, which effloresce sulphate of alumine, or natural alum, with which the Indians of Guayqueries carry on a little trade.

Serpentine is found on the cordillera of Venezuela above micaceous schist, on the surface of Villa de Cura, at the height of 245 toises; between the Cerro de Piedras Negras and the Rio Tucutunemo, here and there green olivin mixed with glimmer, without garnets, schillerspath, or hornblend, but with veins of bluish lardstone.

Grunstein (green rock), original trapp, an intimate union of hornblend and feldspar, sometimes intermixed with sulphureous pyrites and quartz, often confounded with basaltes, and very little known in Europe, is found in strata of two fathoms in thickness, or balls of from three to four feet in diameter, composed of concentric strata united with micaceous schist or original argillaceous schist, in several places of the northern and southern declivity of the cordillera of the mountain Avila, in the sea near Cape Blanc, in a real vein which traverses the strata of gneiss, but intermixed with newer granite, which fills up the vein between Antimano and Carapa near Caracas.

The gray stone contains here red garnets which I have never seen in Europe. I have sent specimens of them to Madrid in the first box which I transmitted to the captain-general of Caracas.

II. Kind of Mountains which form the Transition from Primitive to Alluvial Mountains.

Formation of the Transition of Werner.

This formation is found in particular to the north of the Parima cordillera, opposite to Caccara, and in large masses on the southern declivity of the Venezuela cordillera.

Between the llanos and Morros of S. Juan, between the Villa de Gura and Parapara, between longitude 9° 33′ and 9° 55′, one seems to enter a land of basaltes, on descending from the height of 300 to 63 toises above the level of the sea.

Every thing reminds one here of the mountains of Bilin in Bohemia, or of Vienza in Italy.

The primitive serpentin on the banks of the Tucutunemo, which like that of Silesia contains copper veins, becomes gradually mixed with feldspar and hornblend, and makes the transition into trapp or grunstein.

This trapp is found in stratified masses declining 70° towards the north, or in balls with concentric strata, which, interspersed in calcareous clay, form pyramidal hills; sometimes the transition argillaceous schist of Werner is interspersed in green and very heavy argillaceous schist, which consists of hornblend and argillaceous schist intimately mixed together.

The same argillaceous schist makes a transition near the Quebrada de Piedras Azules into the primitive argillaceous schist above which it lies.

The trapp or grunstein contains also foliaceous olivin, crystallized in pyramids of four faces, a fossil which M. Friesleben discovered on our tour into Bohemia, and deseribed in the Mineralogical Journal of Freyberg, augite with a shelly fracture, leucite in dodecaedra, the sides of the holes and cavities of which are covered with green earth like that of Verona, and a substance which has the splendour of mother-of-pearl, and which I consider as zeolite.

All these interspersed fossils increase towards Parapara, and the trapp there forms real amygdalite.

Above this amygdalite, near the hill Florez, at the entrance into the large valley of Orinoco, lies that remarkable stone which is scarce in Europe, and which Werner describes under the name of porphyry schist.

The hornschist of Charpentier, a kind of rock which accompanies basaltes, forms groups of irregular columns, and by the impression of the ferns which it contains in the middle of the mountains, as discovered by M. Reuss, proves that it is not of volcanic origin.

The porphyry schist of Parapara is a green mass of sonorous stone, which is very hard, acute angled, and has transparent fragments on the edges: it strikes fire with steel, and contains vitreous feldspar.

I did not expect to find this stone again in South America; it however does not form here such groups of grotesque appearance as in Bohemia, and on mount Eugoneide in the Venetian territories, where I have seen it.

III. Alluvial Mountains.

These secondary formations, which are of later origin than the organic bodies of the earth, follow each other in the order of their relative age, as in the plains of Europe, and as has been mentioned by that excellent geologist M.

Von Buch, in his Mineralogical Description of the County of Glatz in Silesia, a small work, which contains valuable ideas and interesting observations.

I found here two formations of compact limestone.

The one makes a transition into the small grained and imperceptibly foliaceous limestone, and is identic with the limestone of the high Alps; the other is compact, exceedingly homogeneous, with several petrifactions of shells, and analogous to the limestone of Jura, Pappenheim, Gibraltar, Verona, Dalmatia, and Suez; a formation of foliaceous gypsum, and another mixed with clay, containing common salt and rock oil.

The saline clay which I always found accompanied with rock salt in the Tyrol, Steyermark, and Salzbourg in Swisserland; marl schist stratified in limestone of the Alps, and two formations of sandstone, one of which is older and almost without petrifactions, sometimes small and large-grained sandstone of the llanos, and the other full of the remains of marine animals, which forms the transition into the compact limestone.

The blue limestone of the Alps, with white veins of calcareous spar, is found on the micaceous schist lying upon the Quebrada Secca near Tuy to the east from the Punta Delgada, on the road from Cumana, on the Impossible towards Bordones, on the island of Trinidad, and on the mountain Paria.

This limestone contains here, as in Swisserland, three formations arranged under each other:— 1st, Repeated strata of black marl schist; marl schist, or cupreous schist of Thuringia, mixed with pyrites, and earth pitch on the Cuchivana near Cumanacoa.

This clay contains carbon, and absorbs the oxygen of the atmospheric air. 2d, Saline clay mixed with rock salt and crystallized gypsum, in which the salt pits of Araga, Pozuelas, and Margaret’s Island are placed.

3d, Small-grained sandstone, with a calcareous base, almost without petrifactions of shells, always penetrated by water, and sometimes with brown strata of ferruginous earth on the Cocollard, Tamirquiri. I am not certain whether the last-mentioned stone lies on the limestone, or is not sometimes covered by it.

This limestone serves as the base for a newer one.

It is exceedingly white and compact, full of holes (Cueva del Guacharo, in which thousands of birds reside, and among which is a new genus of Caprimulgus, from which a kind of fat much used in the country is obtained, Cueva del S. Juan, Cueva del Cuchivano); sometimes porous like the Franconian, and forms grotesque rocks (Morros de S. Juan, de S. Sebastian).

It contains strata of black hornstone, which passes into siliceous schist or Lydian stone (Morro de Barcelona) and Egyptian jasper to the south of Curataquiche.

Over this compact limestone is placed, as on Jura, very beautiful alabaster in large masses at Soro, in Golfo Triste.

All this gypsum contains sulphur as well as the gypsum of Bex and Kretzetzow, and in the Carpathians.

This formation of limestone, with black hornstone and gypsum, seems also to occur in the valley of the Amazon and Rio Negro, where they were found by la Condamine near Cuença, between Racam and Guyausi, on the east side of the Andes.

This limestone and gypsum (the latter in the llano of Barcelona near Cachipé) are often covered in the valleys of Orinoco, and the Amazon river, by a conglomeration or sandstone, with large strata, in which the remains of limestone, quartz, Lydian stone, all of greater antiquity than the sandstone itself, occur.

This conglomeration, breccia, which has a similarity to that of Aranjuez, Salzburg, &c., is extended over more than 18000 square miles in the llanos.

It contains strata with small grains and traces of brown and red iron ore. I have never seen petrifactions in it.

The sandstone full of shells and coral, without any traces of crocodiles in a country which unfortunately contains so many, and which passes into limestone, but on closer examination is intermixed with grains of quartz, is of newer formation, and always nearer the coasts:

P. Araya, Cabo Blanco, Castillo, S. Antonio de Cumana.

It may perhaps be expected that I should close this description with an enumeration of the volcanie productions of this country, which has been convulsed by the most terrible earthquakes, the high summits of which (Duida), and lately some of its caverns (Cueva du Cuchivano), vomit forth flames, where boiling springs are thrown up from Golfo Triste to the Sierra Nevada de Merida (the springs of Triachevar I found to be 72°·3 of Reaumur), where, on the coast of Paria, near Cumacator, there is an air volcano, the noise of which is heard at a great distance, and sulphureous pits in several places as at Guadaloupe—a country where, in the extent of several square miles, the whole surface is undermined and hollow (Tierra Hueca de Cariaco), where, in the year 1766, the earth, after being agitated eleven months by violent shocks, opened on all sides, and poured forth sulphureous water and bitumen; and where, in the midst of the driest plains in the Mera de Guanipa and du Cary, flames burst from the earth.

But nature discharges me from this task.

The effects of the volcanoes in this part of the world are very different from those seen in Europe.

Great and melancholy in their consequences, they change the rocks which are exposed to their action.

The immense revolution of Pelileo and Tonguragua de Zuito has not only covered the earth with lava, but with clayey mud, deposited by the sulphureous water which spouted from the earth.

The sulphureous gypsum, the mixture of sulphureous pyrites in all the rocks, even in granite, the bituminous saline clay, the rock oil, or asphaltum, which every where floats on the water or lies on the ground, the immeasurable quantity of rainwater, and the lakes which penetrate into the earth heated by the sun, the aqueous vapours and immense quantities of hydrogen gas every where disengaged, seem to be the principal causes which contribute to produce these volcanic effects.

The sulphureous pits of Guadaloupe, of Montmisene, St. Christopher de l’Oualiban, St. Lucia, and Montserrat, are in all probability connected with those on the coast of Paria.

These volcanoes, however, belong rather to the province of natural philosophy than of mineralogy; and I must visit other countries before I can venture to form any opinion on so difficult a subject.

May Heaven avert from the eastern side of New Andalusia such a catastrophe as that which has convulsed the plains of Pelileo!

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