The Amazon, or as it is customary to say in those regions, the Upper Maranon, flows through the western part of the longitudinal valley lying between the Cordilleras of Chachapayas and Caxamarca. Comprehending in one point of view, this valley, and that of the Rio Jauja, bounded by the Cordilleras of Tarma and Huarocheri, we are inclined to consider them as one immense basin 180 leagues long, and crossed in the first third of its length, by a dyke, or ridge 18,000 toises broad. In fact, the two alpine lakes of Lauricocha and Chinchaycocha, where the river Amazon and the Rio de Jauja take their rise, are situated south and north of this rocky dyke, which is a prolongation of the knot of Huanuco and Pasco. The Amazon, on issuing from the longitudinal valley which bounds the chains of Caxamarca and Chachacocha, breaks the latter chain; and the point where the great river penetrates the mountains, is very remarkable. Entering the Amazon by the Rio Chamaya or Guancabamba, I found opposite the confluence, the picturesque mountain of Patachuana; but the rocks on both banks of the Amazon begin only between Tambillo and Tomependa (latitude 5 degrees 31 minutes, longitude 80 degrees 56 minutes). From thence to the Pongo de Rentema, a long succession of rocks follow, of which the last is the Pongo de Tayouchouc, between the strait of Manseriche and the village of San Borja. The course of the Amazon, which is first directed north, then east, changes near Puyaya, three leagues north-east of Tomependa. Throughout the whole distance between Tambillo and San Borja, the waters force a way, more or less narrow, across the sandstones of the Cordillera of Chachapoyas. The mountains are lofty near the Embarcadero, at the confluence of the Imasa, where large trees of cinchona, which might be easily transplanted to Cayenne, or the Canaries, approach the Amazon. The rocks in the famous strait of Manseriche are scarcely 40 toises high; and further eastward the last hills rise near Xeberos, towards the mouth of the Rio Huallaga.

I have not yet noticed the extraordinary widening of the Andes near the Apolobamba. The sources of the Rio Beni being found in the spur which stretches northward beyond the confluence of that river with the Apurimac, I shall give to the whole group the name of "the spur of Beni." The following is the most certain information I have obtained respecting those countries, from persons who had long inhabited Apolobamba, the Real das Minas of Pasco, and the convent of Ocopa. Along the whole eastern chain of Titicaca, from La Paz to the knot of Huanuco (latitude 17 1/2 to 10 1/2 degrees) a very wide mountainous land is situated eastward, at the back of the declivity of the Andes. It is not a widening of the eastern chain itself, but rather of the small heights that surround the foot of the Andes like a penumbra, filling the whole space between the Beni and the Pachitca. A chain of hills bounds the eastern bank of the Beni to latitude 8 degrees; for the rivers Coanache and Magua, tributaries of the Ucayali (flowing in latitude 6 and 7 degrees) come from a mountainous tract between the Ucayali and the Javari. The existence of this tract in so eastern a longitude (probably longitude 74 degrees), is the more remarkable, as we find at four degrees of latitude further north, neither a rock nor a hill on the east of Xeberos, or the mouth of the Huallaga (longitude 77 degrees 56 minutes).

We have just seen that the spur of Beni, a sort of lateral branch, loses itself about latitude 8 degrees; the chain between the Ucayali and the Huallaga terminates at the parallel of 7 degrees, in joining, on the west of Lamas, the chain of Chachapayas, stretching between the Huallaga and the Amazon. Finally, the latter chain, to which I have given the designation of central, after forming the rapids and cataracts of the Amazon, between Tomependa and San Borja, turns to north-north-west, and joins the western chain, that of Caxamarca, or the Nevados of Pelagatos and Huaylillas, and forms the great knot of the mountains of Loxa. The mean height of this knot is only from 1000 to 1200 toises: its mild climate renders it peculiarly favourable to the growth of the cinchona trees, the finest kinds of which are found in the celebrated forest of Caxanuma and Uritusinga, between the Rio Zamora and the Cachiyacu, and between Tavacona and Guancabamba. Before the cinchona of Popayan and Santa Fe de Bogota (north latitude 2 1/2 to 5 degrees), of Huacarachuco, Huamalies and Huanuco (south latitude 9 to 11 degrees) became known, the group of the mountains of Loxa had for ages been regarded as the sole region whence the febrifuge bark of cinchona could be obtained. This group occupies the vast territory between Guancabamba, Avayaca, Ona and the ruined towns of Zamora and Loyola, between latitude 5 1/2 and 3 1/4 degrees. Some of the summits (the Paramos of Alpachaca, Saraguru, Savanilla, Gueringa, Chulucanas, Guamani, and Yamoca, which I measured) rise from 1580 to 1720 toises, but are not even sporadically covered with snow, which in this latitude falls only above 1860 to 1900 toises of absolute height. Eastward, in the direction of the Rio Santiago and the Rio de Chamaya, two tributary streams of the Amazon, the mountains lower rapidly: between San Felipe, Matara, and Jaen de Bracamoros, they are not more than 500 or 300 toises.

As we advance from the mica-slate mountain of Loxa towards the north, between the Paramos of Alpachaca and Sara (in latitude 3 degrees 15 minutes) the knot of mountains ramifies into two branches which comprehend the longitudinal valley of Cuenca. This separation continues for a length of only 12 leagues; for in latitude 2 degrees 27 minutes the two Cordilleras again re-unite in the knot of Assuy, a trachytic group, of which the table-land near Cadlud (2428 toises high) nearly enters the region of perpetual snow.

The group of the mountains of Assuy, which affords a very frequented pass of the Andes between Cuenca and Quito (latitude 2 1/2 to 0 degrees 40 minutes south) is succeeded by another division of the Cordilleras, celebrated by the labours of Bouguer and La Condamine, who placed their signals sometimes on one, sometimes on the other of the two chains. The eastern chain is that of Chimborazo (3350 toises) and Carguairazo; the western is the chain of the volcano Sangay, the Collanes, and of Llanganate. The latter is broken by the Rio Pastaza. The bottom of the longitudinal basin that bounds those two chains, from Alausi to Llactacunga, is somewhat higher than the bottom of the basin of Cuenca. North of Llactacanga, 0 degrees 40 minutes latitude, between the tops of Yliniza (2717 toises) and Cotopaxi (2950 toises), of which the former belongs to the chain of Chimborazo, and the latter to that of Sangay, is situated the knot of Chisinche; a kind of narrow dyke that closes the basin, and divides the waters between the Atlantic and the Pacific. The Alto de Chisinche is only 80 toises above the surrounding table-lands. The waters of its northern declivity form the Rio de San Pedro, which, joining the Rio Pita, throws itself into the Gualabamba, or Rio de las Esmeraldas. The waters of the southern declivity, called Cerro de Tiopullo, run into the Rio San Felipe and the Pastaza, a tributary stream of the Amazon.

The bipartition of the Cordilleras re-commences and continues from 0 degrees 40 minutes latitude south to 0 degrees 20 minutes latitude north; that is, as far as the volcano of Imbabura near the villa of Ibarra. The eastern Cordillera presents the snowy summits of Antisana (2992 toises), of Guamani, Cayambe (3070 toises) and of Imbabura; the western Cordillera, those of Corazon, Atacazo, Pichinca (2491 toises) and Catocache (2570 toises). Between these two chains, which may be regarded as the classic soil of the astronomy of the 18th century, is a valley, part of which is again divided longitudinally by the hills of Ichimbio and Poignasi. The table-lands of Puembo and Chillo are situated eastward of those hills; and those of Quito, Inaquito and Turubamba lie westward. The equator crosses the summit of the Nevado de Cayambe and the valley of Quito, in the village of San Antonio de Lulumbamba. When we consider the small mass of the knot of Assuy, and above all, of that of Chisinche, we are inclined to regard the three basins of Cuenca, Hambato and Quito as one valley (from the Paramo de Sarar to the Villa de Ibarra) 73 sea leagues long, from 4 to 5 leagues broad, having a general direction north 8 degrees east, and divided by two transverse dykes one between Alausi and Cuenca (2 degrees 27 minutes south latitude), and the other between Machache and Tambilbo (0 degrees 40 minutes). Nowhere in the Cordillera of the Andes are there more colossal mountains heaped together than on the east and west of this vast basin of the province of Quito, one degree and a half south, and a quarter of a degree north of the equator. This basin which, next to the basin of Titicaca, is the centre of the most ancient native civilization, touches, southward, the knot of the mountains of Loxa, and northward the tableland of the province of Los Pastos.

In this province, a little beyond the villa of Ibarra, between the snowy summits of Cotocache and Imbabura, the two Cordilleras of Quito unite, and form one mass, extending to Meneses and Voisaco, from 0 degrees 21 minutes north latitude to 1 degree 13 minutes. I call this mass, on which are situated the volcanoes of Cumbal and Chiles, the knot of the mountains of Los Pastos, from the name of the province that forms the centre. The volcano of Pasto, the last eruption of which took place in the year 1727, is on the south of Yenoi, near the northern limit of this group, of which the inhabited table-lands are more than 1600 toises above sea-level. It is the Thibet of the equinoctial regions of the New World.

On the north of the town of Pasto (latitude 1 degree 13 minutes north; longitude 79 degrees 41 minutes) the Andes again divide into two branches and surround the table-land of Mamendoy and Almaguer. The eastern Cordillera contains the Sienega of Sebondoy (an alpine lake which gives birth to the Putumayo), the sources of the Jupura or Caqueta, and the Paramos of Aponte and Iscanse. The western Cordillera, that of Mamacondy, called in the country Cordillera de la Costa, on account of its proximity to the shore of the Pacific, is broken by the great Rio de Patias, which receives the Guativa, the Guachicon and the Quilquase. The table-land or intermediary basin has great inequalities; it is partly filled by the Paramos of Pitatumba and Paraguay, and the separation of the two chains appeared to me indistinct as far as the parallel of Almaguer (latitude 1 degree 54 minutes; longitude 79 degrees 15 minutes). The general direction of the Andes, from the extremity of the basin of the province of Quito to the vicinity of Popayan, changes from north 8 degrees east to north 36 degrees east; and follows the direction of the coast of Esmeralda and Barbacoas.

On the parallel of Almaguer, or rather a little north-east of that town, the geological structure of the ground displays very remarkable changes. The Cordillera, to which we have given the name of eastern, that of the lake of Sebondoy, widens considerably between Pansitara and Ceja. The knot of the Paramo de las Papas and of Socoboni gives birth to the great rivers of Cauca and Magdalena, and is divided into two chains, latitude 2 degrees 5 minutes east and west of La Plata, Vieja and Timana. These two chains continue nearly parallel as far as 5 degrees of latitude, and they bound the longitudinal valley through which winds the Rio Magdalena. We shall give the name of the eastern Cordillera of New Grenada to that chain which stretches towards Santa Fe de Bogota, and the Sierra Nevada de Merida, east of Magdalena; the chain which lies between the Magdalena and the Cauca, in the direction of Mariquita, we will call the central Cordillera of New Grenada; and the chain which continues the Cordillera de la Costa from the basin of Almaguer, and separates the bed of the Rio Cauca from the platiniferous territory of Choco, we will designate the western Cordillera of New Grenada. For additional clearness, we may also name the chain, that of Suma Paz, after the colossal group of mountains on the south of Santa Fe de Bogota, which empties the waters of its eastern declivity into the Rio Meta. The second chain may bear the name of the chain of Guanacas or Quindiu, after the two celebrated passages of the Andes, on the road from Santa Fe de Bogota to Popayan. The third chain may be called the chain of Choco, or of the shore. Some leagues south of Popayan (latitude 2 degrees 21 minutes north), west of Paramo de Palitara and the volcano of Purace, a ridge of mica-slate runs from the knot of the mountains of Sacoboni to north-west, and divides the waters between the Pacific and the Caribbean Sea; they flow from the northern declivity into the Rio Cauca, and from the southern declivity, into the Rio de Patias.

The tripartition of the Andes (north latitude 1 3/4 to 2 1/4 degrees) resembles that which takes place at the source of the Amazon in the knot of the mountains of Huanuco and Pasco (latitude 11 degrees south); but the most western of the three chains that bound the basins of the Amazon and the Huallaga, is the loftiest; while that of Choco, or the shore, is the least elevated of the three chains of New Grenada. Ignorance of this tripartition of the Andes in that part of South America near the Rio Atrato and the isthmus of Panama, has led to many erroneous opinions respecting the possibility of a canal that should connect the two seas.

The eastern chain of the Andes of New Grenada* preserves its parallelism during some time with the two other chains, those of Quindiu and Choco; but beyond Tunja (latitude 5 1/2 degrees) it inclines more towards the north-east, passing somewhat abruptly from the direction north 25 degrees east to that of north 45 degrees east. (* I employ a systematic denomination, for the name of the Andes is unknown in the countries situated north of the equator.) It is like a vein that changes its direction; and it rejoins the coast after being greatly enlarged by the grouping of the snowy mountains of Merida. The tripartition of the Cordilleras, and above all, the spreading of their branches, have a vast influence on the prosperity of the nations of New Grenada. The diversity of the superposed table-lands and climates varies the agricultural productions as well as the character of the inhabitants. It gives activity to the exchange of productions, and renews over a vast surface, north of the equator, the picture of the sultry valleys and cool and temperate plains of Peru. It is also worthy of remark that, by the separation of one of the branches of the Cordilleras of Cundinamarca and by the deviation of the chain of Bogota towards the north-east, the colossal group of the mountains of Merida is enclosed in the territory of the ancient Capitania-general of Venezuela, and that the continuity of the same mountainous land from Pamplona to Barquisimeto and Nirgua may be said to have facilitated the political union of the Columbian territory. As long as the central chain (that of Quindiu) presents its snowy summits, no peak of the eastern chain (that of La Suma Paz) rises, in the same parallels, to the limit of perpetual snow. Between latitude 2 and 5 1/2 degrees neither the Paramos situated on the east of Gigante and Neiva, nor the tops of La Suma Paz, Chingasa, Guachaneque, and Zoraca, exceed the height of 1900 to 2000 toises; while on the north of the parallel of Paramo d'Erve (latitude 5 degrees 5 minutes), the last of the Nevados of the central Cordillera, we discover in the eastern chain the snowy summits of Chita (latitude 5 degrees 50 minutes), and of Mucuchies (latitude 8 degrees 12 minutes). Hence it results that from latitude 5 degrees the only mountains covered with snow during the whole year are the Cordilleras of the east; and although the Sierra Nevada of Santa Marta is not, properly speaking, a continuation of the Nevados of Chita and Mucuchies (west of Patute and east of Merida), it is at least very near their meridian.

Having now arrived at the northern extremity of the Cordilleras, comprehended between Cape Horn and the isthmus of Panama, we shall proceed to notice the loftiest summits of the three chains which separate in the knot of the mountains of Socoboni, and the ridge of Roble (latitude 1 degree 50 minutes to 2 degrees 20 minutes). I begin with the most eastern chain, that of Timana and Suma Paz, which divides the tributary streams of the Magdalena and the Meta: it runs by the Paramos de Chingasu, Guachaneque, Zoraca, Toquillo (near Labranza Grande), Chita, Almorsadero, Laura, Cacota, Zumbador and Porqueras, in the direction of the Sierra Nevada de Merida. These Paramos indicate ten partial risings of the back of the Cordilleras. The declivity of the eastern chain is extremely rapid on the eastern side, where it bounds the basin of the Meta and the Orinoco; it is widened on the west by the spurs on which are situated the towns of Santa Fe de Bogota, Tunja, Sogamoso and Leiva. They are like tablelands fixed to the western declivity, and are from 1300 to 1400 toises high; that of Bogota (the bottom of an ancient lake) contains fossil bones of the mastodon, in the plain called (from them) the Campo de Gigantes, near Suacha.

The intermediary, or central chain, runs east of Popayan, by the high plains of Mabasa, the Paramos of Guanacas, Huila, Savelillo, Iraca, Baraguan, Tolima, Ruiz and Herveo, towards the province of Antioquia. In 5 degrees 15 minutes of latitude this chain, the only one that shows traces of recent volcanic fire, in the summits of Sotara and Purace, widens considerably towards the west, and joins the western chain, which we have called the chain of Choco, because the platiniferous land of that province lies on the slope opposite the Pacific ocean. By the union of the two chains, the basin of the province of Popayan is close on the north of Cartago Viejo; and the river of Cauca, issuing from the plain of Buga, is forced, from the Salto de San Antonio, to La Boca del Espiritu Santo, to open its way across the mountains, along a course of from 40 to 50 leagues. The difference of the level is very remarkable in the bottom of the two parallel basins of Cauca and Magdalena. The former, between Cali and Cantago, is from 500 to 404 toises; the latter, from Neiva to Ambalema, is from 265 to 150 toises high. According to different geological hypotheses, it may be said either that the secondary formations have not accumulated to the same thickness between the eastern and central, as between the central and western chains; or, that the deposits have been made on the base of primitive rocks, unequally upheaved on the east and west of the Andes of Quindiu. The average difference of the thickness of these formations is 300 toises. The rocky ridge of the Angostura of Carare branches from the south-east, from the spur of Muzo, through which winds the Rio Negro. By this spur, and by those that come from the west, the eastern and central chains approach between Nares, Honda, and Mendales. In fact, the bed of the Rio Magdalena is narrowed in 5 and 5 degrees 18 minutes, on the east by the mountains of Sergento, and on the west by the spurs that are linked with the granitic mountains of Maraquito and Santa Ana. This narrowing of the bed of the river is in the same parallel with that of the Cauca, near the Salto de San Antonio; but, in the knot of the mountains of Antioquia the central and western chains join each other, while between Honda and Mendales, the tops of the central and eastern chains are so far removed that it is only the spurs of each system that draw near and are confounded together. It is also worthy of remark that the central Cordillera of New Grenada displays the loftiest summit of the Andes in the northern hemisphere. The peak of Tolima (latitude 4 degrees 46 minutes) which is almost unknown even by name in Europe, and which I measured in 1801, is at least 2865 toises high. It consequently surpasses Imbabura and Cotocache in the province of Quito, the Chiles of the table-lands of Los Pastos, the two volcanoes of Popayan and even the Nevados of Mexico and Mount Saint Elias of Russian America. The peak of Tolima, which in form resembles Cotapaxi, is perhaps inferior in height only to the ridge of the Sierra Nevada de Santa Marta, which may be considered as an insulated system of mountains.

The eastern chain, also called the chain of Choco and the east coast (of the Pacific), separates the provinces of Popayan and Antioquia from those of Barbacoas, Raposo and Choco. It is in general but little elevated, compared to the height of the central and eastern chains; it however presents great obstacles to the communications between the valley of Cauca and the shore. On its western slope lies the famous auriferous and platiniferous land,* which has during ages yielded more than 13,000 marks of gold annually. (* Choco, Barbacoas and Brazil are the only countries in which the existence of grains of platinum and palladium has hitherto been fully ascertained. The small town of Barbacoas is situated on the left bank of the Rio Telembi (a tributary of Patias or the Rio del Castigo) a little above the confluence of Telembi and the Guagi or Guaxi, nearly in latitude 1 degree 48 minutes. The ancient Provincia, or rather the Partido del Raposo, comprehends the insalubrious land extending from the Rio Dagua, or San Buenaventura, to the Rio Iscuande, the southern limit of Choco.) This alluvial zone is from ten to twelve leagues broad; its maximum of productiveness lies between the parallels of 2 and 6 degrees latitude; it sensibly impoverishes towards the north and south, and almost entirely disappears between 1 1/4 degree north latitude and the equator. The auriferous soil fills the basin of Cauca, as well as the ravines and plains west of the Cordillera of Choco; it rises sometimes nearly 600 toises above the level of the sea, and descends at least 40 toises.* (* M. Caldas assigns to the upper limit of the zone of gold-washings, only the height of 350 toises. Semanario tome 1 page 18; but I found the Seraderos[?] of Quilichao, on the north of Popayan, to be 565 toises high.) Platinum (and this fact is worthy of attention) has hitherto been found only on the west of the Cordillera of Choco, and not on the east, notwithstanding the analogy of the fragments of rocks of greenstone, phonolite, trachyte, and ferruginous quartz, of which the soil of the two slopes is composed. From the ridge of Los Robles, which separates the table-land of Almaguer from the basin of Cauca, the western chain forms, first, in the Cerros de Carpinteria, east of the Rio San Juan de Micay, the continuation of the Cordillera of Sindagua, broken by the Rio Patias; then, lowering northward, between Cali and Las Juntas de Dagua, and at the elevation of 800 to 900 toises, it sends out considerable spurs (latitude 4 1/4 to 5 degrees) towards the source of the Calima, the Tamana and the Andagueda. The two former of these auriferous rivers are tributary streams of the Rio San Juan del Choco; the second empties its waters into the Atrato. This widening of the western chain forms the mountainous part of Choco: here, between the Tado and Zitara, called also Francisco de Quibdo, lies the isthmus of Raspadura, across which a monk traced a navigable line of communication between the two oceans. The culminant point of this system of mountains appears to be the Peak of Torra, situated south-east of Novita.

The northern extremity of this enlargement of the Cordillera of Choco, which I have just described, corresponds with the junction formed on the east, between the same Cordillera and the central chain, that of Quindiu. The mountains of Antioquia, on which we have the excellent observations of Mr. Restrepo, may be called a knot of mountains, and on the northern limit of the plains of Buga, or the basin of Cauca, they join the central and western chains. The ridge of the eastern Cordillera is at the distance of thirty-five leagues from this knot, so that the contraction of the bed of the Rio Magdalena, between Honda and Ambalema, is caused only by the approximation of the spurs of Mariquita and Guaduas. There is not, therefore, properly speaking, a group of mountains between latitude 5 and 5 1/4 degrees, uniting the three chains at once. In the group of the province of Antioquia, which forms the junction of the central and western Cordilleras, we may distinguish two great masses; one between the Magdalena and the Cauca, and the other between the Cauca and the Atrato. The first of these masses, which is linked most immediately to the snowy summits of Herveo, gives birth on the east to the Rio de la Miel and the Nare; and on the north to Porce and Nechi; its average height is only from 1200 to 1350 toises. The culminant point appears to be near Santa Rosa, south-west of the celebrated Valley of Bears (Valle de Osos). The towns of Rio Negro and Marinilla are built on table-lands 1060 toises high. The western mass of the knot of the mountains of Antioquia, between the Cauca and the Atrato, gives rise, on its western descent, to the Rio San Juan, Bevara, and Murri. It attains its greatest height in the Alto del Viento, north of Urrao, known to the first conquistadores by the name of the Cordilleras of Abide or Dabeida. This height (latitude 7 degrees 15 minutes) does not, however, exceed 1500 toises. Following the western slope of this system of mountains of Antioquia, we find that the point of partition of the waters that flow towards the Pacific and the Caribbean Sea (latitude 5 1/2 and 6 degrees ) nearly corresponds with the parallel of the isthmus of Raspadura, between the Rio San Juan and the Atrato. It is remarkable that in this group, more than 30 leagues broad, without sharp summits, between latitude 5 1/4 and 7 degrees, the highest masses rise towards the west; while, further south, before the union of the two chains of Quindiu and Choco, we saw them on the east of Cauca.

The ramifications of the knot of Antioquia, on the north of the parallel 7 degrees, are very imperfectly known; it is observed only that their lowering is in general more rapid and complete towards the north-west, in the direction of the ancient province of Biruquete and Darien, than towards the north and north-east, on the side of Zaragoza and Simiti. From the northern bank of the Rio Nare, near its confluence with the Samana, a spur stretches out, known by the name of La Simitarra, and the Mountains of San Lucar. We may call it the first branch of the group of Antioquia. I saw it, in going up the Rio Magdalena, on the west, from the Regidor and the mouth of the Rio Simiti, as far as San Bartolome (on the south of the mouth of the Rio Sogamozo); while, eastward, in latitude 7 3/4 and 8 1/4 degrees, the spur of the mountains of Ocana appear in the distance; they are inhabited by some tribes of Molitone Indians. The second branch of the group of Antioquia (west of Samitarra) commences at the mountains of Santa Rosa, stretches out between Zaragoza and Caceres, and terminates abruptly at the confluence of the Rio Nechi (latitude 8 degrees 33 minutes): at least if the hills, often conical, between the mouth of the Rio Sinu and the small town of Tolu, or even the calcareous heights of Turbaco and Popa, near Carthagena, may not be regarded as the most northern prolongation of this second branch. A third advances towards the gulf of Uraba or Darien, between the Rio San Jorge and the Atrato. It is linked southward with the Alto del Viento, or Sierra de Abide, and is rapidly lost, advancing as far as the parallel of 8 degrees. Finally, the fourth branch of the Andes of Antioquia, situated westward of Zitara and the Rio Atrato, undergoes, long before it enters the isthmus of Panama, such a depression, that between the Gulf of Cupica and the embarcadero of the Rio Naipipi, we find only a plain across which M. Gogueneche has projected a canal for the junction of the two seas. It would be interesting to know the configuration of the strata between Cape Garachine, or the Gulf of St. Miguel, and Cape Tiburon, especially towards the source of the Rio Tuyra and Chucunaque or Chucunque, so as to determine with precision where the mountains of the isthmus of Panama begin to rise; mountains whose elevation does not appear to be more than 100 toises. The interior of Darfur is not more unknown to geographers than the humid, insalubrious forest-land which extends on the north-west of Betoi and the confluence of the Bevara with the Atrato, towards the isthmus of Panama. All that we positively know of it hitherto is that between Cupica and the left bank of the Atrato there is either a land-strait, or a total absence of the Cordillera. The mountains of the isthmus of Panama, by their direction and their geographical position, may be considered as a continuation of the mountains of Antioquia and Choco; but on the west of Bas-Atrato, there is scarcely a ridge in the plain. We do not find in this country a group of interposed mountains like that which links (between Barquisimeto, Nirgua and Valencia) the eastern chain of New Grenada (that of Suma Paz and the Sierra Nevada de Merida) to the Cordillera of the shore of Venezuela.

The Cordillera of the Andes, considered in its whole extent, from the rocky wall of the island of Diego Ramirez to the isthmus of Panama, is sometimes ramified into chains more or less parallel, and sometimes articulated by immense knots of mountains. We distinguish nine of those knots, and consequently an equal number of branching-points and ramifications. The latter are generally bifurcations. The Andes are twice only divided into three chains; in the knot of Huanuco, near the source of the Amazon, and the Huallaga (latitude 10 to 11 degrees) and in the knot of the Paramo de las Papas (latitude 2 degrees), near the source of the Magdalena and the Cauca. Basins, almost shut in at their extremities, parallel with the axis of the Cordillera and bounded by two knots and two lateral chains, are characteristic features of the structure of the Andes. Among these knots of mountains some, for instance those of Cuzco, Loxa and Los Pastos, comprise 3300, 1500 and 1130 square leagues, while others no less important in the eye of the geologist are confined to ridges or transversal dykes. To the latter belong the Altos de Chisinche (latitude 0 degrees 40 minutes south) and the Los Robles (latitude 2 degrees 20 minutes north), on the south of Quito and Popayan. The knot of Cuzco, so celebrated in the annals of Peruvian civilization, presents an average height of from 1200 to 1400 toises, and a surface nearly three times greater than the whole of Switzerland. The ridge of Chisinche, which separates the basins of Tacunga and Quito, is 1580 toises high, but scarcely a mile broad. The knots or groups which unite several partial chains have not the highest summits, either in the Andes or, for the most part, in the great mountain ranges of the old continent; it is not even certain that there is always in those knots a widening of the chain. The greatness of the mass, and the height so long attributed to points whence several considerable branches issue, was founded either on theoretic ideas or on false measures. The Cordilleras were compared to rivers that swell as they receive a number of tributary streams.

Among the basins which the Andes present, and which form probably as many lakes or small inland seas, those of Titicaca, Rio Jauja and the Upper Maranon, comprise respectively 3500, 1300, and 2400 square leagues of surface.* (* I here subjoin some measures interesting to geologists. Area of the Andes, from Tierra del Fuego to the Paramo de las Rosas (latitude 9 1/4 degrees north), where the mountainous land of Tocuyo and Barquesimeto begins, part of the Cordillera of the shore of Venezuela, 58,900 square leagues, (20 to a degree) the four spurs of Cordova, Salta, Cochabamba and Beni alone, occupy 23,300 square leagues of this surface, and the three basins contained between latitude 6 and 20 degrees south measure 7200 square leagues. Deducting 33,200 square leagues for the whole of the enclosed basins and spurs, we find, in latitude 65 degrees, the area of the Cordilleras elevated in the form of walls, to be 25,700 square leagues, whence results (comprehending the knots, and allowing for the inflexion of the chains) an average breadth of the Andes of 18 to 20 leagues. The valleys of Huallaga and the Rio Magdalena are not comprehended in these 58,900 square leagues, on account of the diverging direction of the chain, east of Cipoplaya and Santa Fe de Bogota.) The first is so encompassed that no drop of water can escape except by evaporation; it is like the enclosed valley of Mexico,* (* We consider it in its primitive state, without respect to the gap or cleft of the mountains, known by the name of Desaghue de Huehuetoca.) and of those numerous circular basins which have been discerned in the moon, and which are surrounded by lofty mountains. An immense alpine lake characterizes the basin of Tiahuanaco or Titicaca; this phenomenon is the more worthy of attention, as in South America there are scarcely any of those reservoirs of fresh water which are found at the foot of the European Alps, on the northern and southern slopes, and which are permanent during the season of drought. The other basins of the Andes, for instance, those of Jauja, the Upper Maranon and Cauca, pour their waters into natural canals, which may be considered as so many crevices situated either at one of the extremities of the basin, or on its banks, nearly in the middle of the lateral chain. I dwell on this articulated form of the Andes, on those knots or transverse ridges, because, in the continuation of the Andes called the Cordilleras of the shore of Venezuela, we shall find the same transverse dykes, and the same phenomena.

The ramification of the Andes and of all the great masses of mountains into several chains merits particular consideration in reference to the height more or less considerable of the bottom of the enclosed basins, or longitudinal valleys. Geologists have hitherto directed more attention to the successive narrowing of these basins, their depth compared with the walls of rock that surround them, and the correspondence between the re-entering and the salient angles, than to the level of the bottom of the valleys. No precise measure has yet fixed the absolute height of the three basins of Titicaca, Jauja and the Upper Maranon;* (* I am inclined to believe that the southern part of the basin of the Upper Maranon, between Huary and Huacarachuco, exceeds 350 toises.) but I was fortunate enough to be able to determine the six other basins, or longitudinal valleys, which succeed each other, as if by steps, towards the north. The bottom of the valley of Cuenca, between the knots of Loxa and Assuay, is 1350 toises; the valley of Allansi and of Hambato, between the knot of the Assuay and the ridge of Chisinche, 1320 toises; the valley of Quito in the eastern part, 1340 toises, and in the western part, 1490 toises; the basin of Almaguer, 1160 toises; the basin of the Rio Cauca, between the lofty plains of Cali, Buga, and Cartago, 500 toises; the valley of Magdalena, first between Neiva and Honda, 200 toises; and further on, between Honda and Mompox, 100 toises of average height above the level of the sea.* (* In the region of the Andes comprehended between 4 degrees of south latitude and 2 degrees of north, the longitudinal valleys or basins inclosed by parallel chains are regularly between 1200 and 1500 toises high; while the transversal valleys are remarkable for their depression, or rather the rapid lowering of their bottom. The valley of Patias, for instance, running from north-east to south-west is only 350 toises of absolute height, even above the junction of the Rio Guachion with the Quilquasi, according to the barometric measures of M. Caldas; and yet it is surrounded by the highest summits, the Paramos de Puntaurcu and Mamacondy. Going from the plains of Lombardy, and penetrating into the Alps of the Tyrol, by a line perpendicular to the axis of the chain, we advance more than 20 marine leagues towards the north, yet we find the bottom of the valley of the Adige and of Eysack near Botzen, to be only 182 toises of absolute height, an elevation which exceeds but 117 toises that of Milan. From Botzen however, to the ridge of Brenner (culminant point 746 toises) is only 11 leagues. The Valais is a longitudinal valley; and in a barometric measurement which I made very recently from Paris to Naples and Berlin, I was surprised to find that from Sion to Brigg, the bottom of the valley rises only to from 225 to 350 toises of absolute height; nearly the level of the plains of Switzerland, which, between the Alps and the Jura, are only from 274 to 300 toises.) In this region, which has been carefully measured, the different basins lower very sensibly from the equator northward. The elevation of the bottom of enclosed basins merits great attention in connection with the causes of the formation of the valleys. I do not deny that the depressions in the plains may be sometimes the effect of ancient pelagic currents, or slow erosions. I am inclined to believe that the transversal valleys, resembling crevices, have been widened by running waters; but these hypotheses of successive erosions cannot well be applied to the completely enclosed basins of Titicaca and Mexico. These basins, as well as those of Jauja, Cuenca and Almaguer, which lose their waters only by a lateral and narrow issue, owe their origin to a cause more instantaneous, more closely linked with the upheaving of the whole chain. It may be said that the phenomenon of the narrow declivities of the Sarenthal and of the valley of Eysack in the Tyrol, is repeated at every step, and on a grander scale, in the Cordilleras of equinoctial America. We seem to recognize in the Cordilleras those longitudinal sinkings, those rocky vaults, which, to use the expression of a great geologist,* "are broken when extended over a great space, and leave deep and almost perpendicular rents." (* Von Buch, Tableau du Tyrol meridional page 8 1823.)

If, to complete the sketch of the structure of the Andes from Tierra del Fuego to the northern Polar Sea, we pass the boundaries of South America, we find that the western Cordillera of New Grenada, after a great depression between the mouth of the Atrato and the gulf of Cupica, again rises in the isthmus of Panama to 80 or 100 toises high, augmenting towards the west, in the Cordilleras of Veragua and Salamanca,* and extending by Guatimala as far as the confines of Mexico. (* If it be true, as some navigators affirm, that the mountains at the north-western extremity of the republic of Columbia, known by the names of Silla de Veragua, and Castillo del Choco, be visible at 36 leagues distance, the elevation of their summits must be nearly 1400 toises, little lower than the Silla of Caracas.) Within this space it extends along the coast of the Pacific where, from the gulf of Nicoya to Soconusco (latitude 9 1/2 to 16 degrees) is found a long series of volcanoes,* most frequently insulated, and sometimes linked to spurs or lateral branches. (* See the list of twenty-one volcanoes of Guatimala, partly extinct and partly still burning, given by Arago and myself, in the Annuaire du Bureau des Longitudes pour 1824 page 175. No mountain of Guatimala having been hitherto measured, it is the more important to fix approximately the height of the Volcan de Agua, or the Volcano of Pacaya, and the Volcan de Fuego, called also Volcano of Guatimala. Mr. Juarros expressly says that this volcano which, by torrents of water and stones, destroyed, on the 11th September, 1541, the Ciudad Vieja, or Almolonga (the ancient capital of the country, which must not be confounded with the ancient Guatimala), is covered with snow, during several months of the year. This phenomenon would seem to indicate a height of more than 1750 toises.) Passing the isthmus of Tehuantepecor Huasacualco, on the Mexican territory, the Cordillera of central America extends on toward the intendancia of Oaxaca, at an equal distance from the two oceans; then from 18 1/2 to 21 degrees latitude, from Misteca to the mines of Zimapan, it approximates to the eastern coast. Nearly in the parallel of the city of Mexico, between Toluca, Xalapa and Cordoba, it attains its maximum height; several colossal summits rising to 2400 and 2770 toises. Farther north the chain called Sierra Madre runs north 40 degrees west towards San Miguel el Grande and Guanaxuato. Near the latter town (latitude 21 degrees 0 minutes 15 seconds) where the richest silver mines of the known world are situated, it widens in an extraordinary degree and separates into three branches. The most eastern branch advances towards Charcas and the Real de Catorce, and lowers progressively (turning to north-east) in the ancient kingdom of Leon, in the province of Cohahuila and Texas. That branch is prolonged from the Rio Colorado de Texas, crossing the Arkansas near the confluence of the Mississippi and the Missouri (latitude 38 degrees 51 minutes). In those countries it bears the name of the Mountains of Ozark,* and attains 300 toises of height. (* Ozark is at once the ancient name of Arkansas and of the tribe of Quawpaw Indians who inhabit the banks of that great river. The culminant point of the Mountains of Ozark is in latitude 37 1/2 degrees, between the sources of the White and Osage rivers.) It has been supposed that on the east of the Mississippi (latitude 44 to 46 degrees) the Wisconsin Hills, which stretch out to north-north-east in the direction of Lake Superior, may be a continuation of the mountains of Ozark. Their metallic wealth seems to denote that they are a prolongation of the eastern Cordillera of Mexico. The western branch or Cordillera occupies a part of the province of Guadalajara and stretches by Culiacan, Aripe and the auriferous lands of the Pimeria Alta and La Sonora, as far as the banks of the Rio Gila (latitude 33 to 34 degrees), one of the most ancient dwellings of the Aztek nations. We shall soon see that this western chain appears to be linked by the spurs that advance to the west, with the maritime Alps of California. Finally, the central Cordillera of Anahuac, which is the most elevated, runs first from south-east to north-west, by Zacatecas towards Durango, and afterwards from south to north, by Chihuahua, towards New Mexico. It takes successively the names of Sierra de Acha, Sierra de Los Mimbres, Sierra Verde, and Sierra de las Grullas, and about the 29 and 39 degrees of latitude, it is connected by spurs with two lateral chains, those of the Texas and La Sonora, which renders the separation of the chains more imperfect than the trifurcations of the Andes in South America.

That part of the Cordilleras of Mexico which is richest in silver beds and veins, is comprehended between the parallels of Oaxaca and Cosiquiriachi (latitude 16 1/2 to 29 degrees); the alluvial soil that contains disseminated gold extends some degrees still further northwards. It is a very striking phenomenon that the gold-washing of Cinaloa and Sonora, like that of Barbacoas and Choco on the south and north of the isthmus of Panama, is uniformly situated on the west of the central chain, on the descent opposite the Pacific. The traces of a still-burning volcanic fire which was no longer seen, on a length of 200 leagues, from Pasto and Popayan to the gulf of Nicoya (latitude 1 1/4 to 9 1/2 degrees), become very frequent on the western coast of Guatimala (latitude 9 1/2 to 16 degrees); these traces of fire again cease in the gneiss-granite mountains of Oaxaca, and re-appear, perhaps for the last time, towards the north, in the central Cordillera of Anahuac, between latitude 18 1/4 and 19 1/2 degrees, where the volcanoes of Taxtla, Orizaba, Popocatepetl, Toluca, Jorullo and Colima appear to be situated in a crevice* extending from east-south-east to west-north-west, from one ocean to the other. (* On this zone of volcanoes is the parallel of the greatest heights of New Spain. If the survey of Captain Basil Hall afford results alike certain in latitude and in longitude, the volcano of Colima is north of the parallel of Puerto de Navidad in latitude 19 degrees 36 minutes; and, like the volcano of Tuxtla, if not beyond the zone, at least beyond the average parallel of the volcanic fire of Mexico, which parallel seems to be between 18 degrees 59 minutes and 19 degrees 12 minutes.) This line of summits, several of which enter the limit of perpetual snow, and which are the loftiest of the Cordilleras from the peak of Tolima (latitude 40 degrees 46 minutes north), is almost perpendicular to the great axis of the chain of Guatimala and Anahuac, advancing to the 27th parallel, uniformly north 42 degrees east. A characteristic feature of every knot, or widening of the Cordilleras, is that the grouping of the summits is independent of the general direction of the axis. The backs of the mountains in New Spain form very elevated plains, along which carriages can roll for an extent of 400 leagues, from the capital to Santa-Fe and Taos, near the sources of Rio del Norte. This immense table-land, in 19 and 24 1/2 degrees, is constantly at the height of from 950 to 1200 toises, that is, at the elevation of the passes of the Great Saint Bernard and the Splugen. We find on the back of the Cordilleras of Anahuac, which lower progressively from the city of Mexico towards Taos, a succession of basins: they are separated by hills little striking to the eye of the traveller because they rise only from 250 to 400 toises above the surrounding plains. The basins are sometimes closed, like the valley of Tenochtitlan, where lie the great Alpine lakes, and sometimes they exhibit traces of ancient ejections, destitute of water.

Between latitude 33 and 38 degrees, the Rio del Norte forms, in its upper course, a great longitudinal valley; and the central chain seems here to be divided into several parallel ranges. This distribution continues northward, in the Rocky Mountains,* where, between the parallels of 37 and 41 degrees, several summits covered with eternal snow (Spanish Peak, James Peak and Big Horn) are from 1600 to 1870 toises of absolute height. (* The Rocky Mountains have been at different periods designated by the names of Chypewyan, Missouri, Columbian, Caous, Stony, Shining and Sandy Mountains.) Towards latitude 40 degrees south of the sources of the Paduca, a tributary of the Rio de la Plata, a branch known by the name of the Black Hills, detaches itself towards the north-east from the central chain. The Rocky Mountains at first seem to lower considerably in 46 and 48 degrees; and then rise to 48 and 49 degrees, where their tops are from 1200 to 1300 toises, and their ridge near 950 toises. Between the sources of the Missouri and the River Lewis, one of the tributaries of the Oregon or Columbia, the Cordilleras form in widening, an elbow resembling the knot of Cuzco. There, also, on the eastern declivity of the Rocky Mountains, is the partition of water between the Caribbean Sea and the Polar Sea. This point corresponds with those in the Andes of South America, at the spur of Cochabamba, on the east, latitude 19 degrees 20 minutes south; and in the Alto de los Robles (latitude 2 degrees 20 minutes north), on the west. The ridge that separates the Rocky Mountains extends from west to east, towards Lake Superior, between the basins of the Missouri and those of Lake Winnipeg and the Slave Lake. The central Cordillera of Mexico and the Rocky Mountains follow the direction north 10 degrees west, from latitude 25 to 38 degrees; the chain from that point to the Polar Sea prolongs in the direction north 24 degrees west, and ends in the parallel 69 degrees, at the mouth of the Mackenzie River.*

(* The eastern boundary of the Rocky Mountains lies:— In 38 degrees latitude : 107 degrees 20 minutes longitude. In 40 degrees latitude : 108 degrees 30 minutes longitude. In 63 degrees latitude : 124 degrees 40 minutes longitude. In 68 degrees latitude : 130 degrees 30 minutes longitude.)

In thus developing the structure of the Cordilleras of the Andes from 56 degrees south to beyond the Arctic circle, we see that its northern extremity (longitude 130 degrees 30 minutes) is nearly 61 degrees of longitude west of its southern extremity (longitude 60 degrees 40 minutes); this is the effect of the long-continued direction from south-east to north-west north of the isthmus of Panama. By the extraordinary breadth of the New Continent, in the 30 and 60 degrees north latitude, the Cordillera of the Andes, continually approaching nearer to the western coast in the southern hemisphere, is removed 400 leagues on the north from the source of the Rio de la Paz. The Andes of Chile may be considered as maritime Alps,* (* Geognostically speaking, a littoral chain is not a range of mountains forming of itself the coast; this name is extended to a chain separated from the coast by a narrow plain.) while, in their most northern continuation, the Rocky Mountains are a chain in the interior of a continent. There is, no doubt, between latitude 23 and 60 degrees from Cape Saint Lucas in California, to Alaska on the western coast of the Sea of Kamschatka, a real littoral Cordillera; but it forms a system of mountains almost entirely distinct from the Andes of Mexico and Canada. This system, which we shall call the Cordillera of California, or of New Albion, is linked between latitude 33 and 34 degrees with the Pimeria alta, and the western branch of the Cordilleras of Anahuac; and between latitude 45 and 53 degrees, with the Rocky Mountains, by transversal ridges and spurs that widen towards the east. Travellers who may at some future time pass over the unknown land between Cape Mendocino and the source of the Rio Colorado, may perhaps inform us whether the connexion of the maritime Alps of California or New Albion, with the western branch of the Cordilleras of Mexico, resembles that which, notwithstanding the depression, or rather total interruption observed on the west of the Rio Atrato, is admitted by geographers to exist between the mountains of the isthmus of Panama and the western branch of the Andes of New Grenada. The maritime Alps, in the peninsula of Old California, rise progressively towards the north in the Sierra of Santa Lucia (latitude 34 1/2 degrees), in the Sierra of San Marcos (latitude 37 to 38 degrees) and in the Snowy Mountains near Cape Mendocino (latitude 39 degrees 41 minutes); the last seem to attain at least the height of 1500 toises. From Cape Mendocino the chain follows the coast of the Pacific, but at the distance of from twenty to twenty-five leagues. Between the lofty summits of Mount Hood and Mount Saint Helen, in latitude 45 3/4 degrees, the chain is broken by the River Columbia. In New Hanover, New Cornwall and New Norfolk these rents of a rocky coast are repeated, these geologic phenomena of the fjords that characterize western Patagonia and Norway. At the point where the Cordillera turns towards the west (latitude 58 3/4 degrees, longitude 139 degrees 40 minutes) there are two volcanic peaks, one of which (Mount Saint Elias) perhaps equals Cotopaxi in height; the other (Fair-Weather Mountain) equals the height of Mount Rosa. The elevation of the former exceeds all the summits of the Cordilleras of Mexico and the Rocky Mountains, north of the parallel 19 1/4 degrees; it is even the culminant point in the northern hemisphere, of the whole known world north of 50 degrees of latitude. North-west of the peaks of Saint Elias and Fair-Weather the chain of California widens considerably in the interior of Russian America. Volcanoes multiply in number as we advance westward, in the peninsula of Alaska and the Fox Islands, where the volcano Ajagedan rises to the height of 1175 toises above the level of the sea. Thus the chain of the maritime Alps of California appears to be undermined by subterraneous fires at its two extremities; on the north in 60 degrees of latitude, and on the south, in 28 degrees, in the volcanoes of the Virgins.* (* Volcanes de las Virgenes. The highest summit of Old California, the Cerro de la Giganta (700 toises), appears to be also an extinguished volcano.) If it were certain that the mountains of California belong to the western branch of the Andes of Anahuac, it might be said that the volcanic fire, still burning, abandons the central Cordillera when it recedes from the coast, that is, from the volcano of Colima; and that the fire is borne on the north-west by the peninsula of Old California, Mount Saint Elias, and the peninsula of Alaska, towards the Aleutian Islands and Kamschatka.

I shall terminate this sketch of the structure of the Andes by recapitulating the principal features that characterize the Cordilleras, north-west of Darien.

Latitude 8 to 11 degrees. Mountains of the isthmus of Panama, Veragua and Costa Rica, slightly linked to the western chain of New Grenada, which is that of Choco.

Latitude 11 to 16 degrees. Mountains of Nicaragua and Guatimala; line of volcanoes north 50 degrees west, for the most part still burning, from the gulf of Nicoya to the volcano of Soconusco.

Latitude 16 to 18 degrees. Mountains of gneiss-granite in the province of Oaxaca.

Latitude 18 1/2 to 19 1/2 degrees. Trachytic knot of Anahuac, parallel with the Nevados and the burning volcanoes of Mexico.

Latitude 19 1/2 to 20 degrees. Knot of the metaliferous mountains of Guanaxuato and Zacatecas.

Latitude 21 3/4 to 22 degrees. Division of the Andes of Anahuac into three chains:

Eastern chain (that of Potosi and Texas), continued by the Ozark and Wisconsin mountains, as far as Lake Superior.

Central chain (of Durango, New Mexico and the Rocky Mountains), sending on the north of the source of the river Platte (latitude 42 degrees) a branch (the Black hills) to north-east, widening greatly between the parallels 46 and 50 degrees, and lowering progressively as it approaches the mouth of Mackenzie River (latitude 68 degrees).

Western chain (of Cinaloa and Sonora). Linked by spurs to the maritime Alps, or mountains of California.

We have yet no means of judging with precision the elevation of the Andes south of the knot of the mountains of Loxa (south latitude 3 degrees 5), but we know that on the north of that knot the Cordilleras rise five times higher than the majestic elevation of 2600 toises:

In the group of Quito, 0 to 2 degrees south latitude (Chimborazo, Antisano, Cayambe, Cotopaxi, Collanes, Yliniza, Sangay, Tungurahua.)

In the group of Cundinamarca, latitude 4 3/4 degrees north (peak of Tolima, north of the Andes of Quindiu).

In the group of Anahuac, from latitude 18 degrees 59 minutes to 19 degrees 12 minutes (Popocatepetl or the Great Volcano of Mexico, and Peak of Orizaba). If we consider the maritime Alps or mountains of California and New Norfolk, either as a continuation of the western chain of Mexico, that of Sonora, or as being linked by spurs to the central chain, that of the Rocky Mountains, we may add to the three preceding groups:

The group of Russian America, from latitude 60 to 70 degrees (Mount Saint Elias). Over an extent of 63 degrees of latitude, I know only twelve summits of the Andes which reach the height of 2600 toises, and consequently exceed by 140 toises, the height of Mont Blanc. Only three of these twelve summits are situated north of the isthmus of Panama.

2. INSULATED GROUP OF THE SNOWY MOUNTAINS OF SANTA MARTA.

In the enumeration of the different systems of mountains, I place this group before the littoral chain of Venezuela, though the latter, being a northern prolongation of the Cordillera of Cundinamarca, is immediately linked with the chain of the Andes. The Sierra Nevado of Santa Marta is encompassed within two divergent branches of the Andes, that of Bogota, and that of the isthmus of Panama. It rises abruptly like a fortified castle, amidst the plains extending from the gulf of Darien, by the mouth of the Magdalena, to the lake of Maracaybo. The old geographers erroneously considered this insulated group of mountains covered with eternal snow, as the extremity of the high Cordilleras of Chita and Pamplona. The loftiest ridge of the Sierra Nevada de Santa Marta is only three or four leagues in length from east to west; it is bounded (at nine leagues distance from the coast) by the meridians of the capes of San Diego and San Augustin. The culminant points, called El Picacho and Horqueta, are near the western border of the group; they are entirely separated from the peak of San Lorenzo, also covered with eternal snow, but only four leagues distant from the port of Santa Marta, towards the south-east. I saw this latter peak from the heights that surrounded the village of Turbaco, south of Carthagena. No precise measurement has hitherto given us the height of the Sierra Nevada, which Dampier affirms to be one of the highest mountains of the northern hemisphere. Calculations founded on the maximum of distance at which the group is discerned at sea, give a height of more than 3004 toises. That the group of the mountains of Santa Marta is insulated is proved by the hot climate of the lands (tierras calientes) that surround it. Low ridges and a succession of hills indicate, perhaps, an ancient connection between the Sierra Nevada de Santa Marta on one side, by the Alto de las Minas, with the phonolitic and granitic rocks of the Penon and Banca, and on the other, by the Sierra de Perija, with the mountains of Chiliguana and Ocana, which are the spurs of the eastern chain of the Andes of New Grenada. In this latter chain, the febrifuge species of cinchona (corollis hirsutis, staminibus inclusis) are found in the Sierra Nevada de Merida; but the real cinchona, the most northern of South America, is found in the temperate region of the Sierra Nevada de Santa Marta.

3. LITTORAL CHAIN OF VENEZUELA.

This is the system of mountains the configuration and direction of which have excited so powerful an influence on the cultivation and commerce of the ancient Capitania General of Venezuela. It bears different names, as the mountains of Coro, of Caracas, of the Bergantin, of Barcelona, of Cumana, and of Paria; but all these names belong to the same chain, of which the northern part runs along the coast of the Caribbean Sea. This system of mountains, which is 160 leagues long,* is a prolongation of the eastern Cordillera of the Andes of Cundinamarca. (* It is more than double the length of the Pyrenees, from Cape Creux to the point of Figuera.) There is an immediate connection of the littoral chain with the Andes, like that of the Pyrenees with the mountains of Asturia and Galicia; it is not the effect of transversal ridges, like the connection of the Pyrenees with the Swiss Alps, by the Black Mountain and the Cevennes. The points of junction are between Truxillo and the lake of Valencia.

The eastern chain of New Grenada stretches north-east by the Sierra Nevada de Merida, as well as by the four Paramos of Timotes, Niquitao, Bocono and Las Rosas, of which the absolute height cannot be less than from 1400 to 1600 toises. After the Paramo of Las Rosas, which is more elevated than the two preceding, there is a great depression, and we no longer see a distinct chain or ridge, but merely hills, and high table-lands surrounding the towns of Tocuyo and Barquisimeto. We know not the height even of Cerro del Altar, between Tocuyo and Caranacatu; but we know by recent measures that the most inhabited spots are from 300 to 350 toises above sea-level. The limits of the mountainous land between Tocuyo and the valleys of Aragua are, the plains of San Carlos on the south, and the Rio Tocuyo on the north; the Rio Siquisique flows into that river. From the Cerro del Altar on the north-east towards Guigue and Valencia, succeed, as culminant points, the mountains of Santa Maria (between Buria and Nirgua); then the Picacho de Nirgua, supposed to be 600 toises high; and finally Las Palomeras and El Torito (between Valencia and Nirgua). The line of water-partition runs from west to east, from Quibor to the lofty savannahs of London, near Santa Rosa. The waters flow on the north, towards the Golfo triste of the Caribbean Sea; and on the south, towards the basins of the Apure and the Orinoco. The whole of this mountainous country, by which the littoral chain of Caracas is linked to the Cordilleras of Cundinamarca, was celebrated in Europe in the middle of the nineteenth century; for that part of the territory formed of gneiss-granite, and lying between the Rio Tocuyo and the Rio Yaracui, contains the auriferous veins of Buria, and the copper-mine of Aroa which is worked at the present day. If, across the knot of the mountains of Barquisimeto, we trace the meridians of Aroa, Nirgua and San Carlos, we find that on the north-west that knot is linked with the Sierra de Coro, and on the north-east with the mountains of Capadare, Porto Cabello and the Villa de Cura. It may be said to form the eastern wall of that vast circular depression of which the lake of Maracaybo is the centre and which is bounded on the south and west by the mountains of Merida, Ocana, Perija and Santa Marta.

The littoral chain of Venezuela presents towards the centre and the east the same phenomena of structure as those observed in the Andes of Peru and New Grenada; namely, the division into several parallel ranges and the frequency of longitudinal basins or valleys. But the irruptions of the Caribbean Sea having apparently overwhelmed, at a very remote period, a part of the mountains of the shore, the ranges or partial chains are interrupted and some basins have become oceanic gulfs. To comprehend the Cordillera of Venezuela in mass we must carefully study the direction and windings of the coast from Punta Tucacas (west of Porto Cabello) as far as Punta de la Galera of the island of Trinidad. That island, those of Los Testigos, Marguerita and Tortuga constitute, with the mica-slates of the peninsula of Araya, one and the same system of mountains. The granitic rocks which appear between Buria, Duaca and Aroa cross the valley of the Rio Yaracui and draw near the shore, whence they extend, like a continuous wall, from Porto Cabello to Cape Codera. This prolongation forms the northern chain of the Cordillera of Venezuela and is traversed in going from south to north, either from Valencia and the valleys of Aragua, to Burburata and Turiamo, or from Caracas to La Guayra. Hot springs* issue from those mountains (* The other hot springs of the Cordillera of the shore are those of San Juan, Provisor, Brigantin, the gulf of Cariaco, Cumucatar and Irapa. MM. Rivero and Boussingault, who visited the thermal waters of Mariara in February, 1823, during their journey from Caracas to Santa Fe de Bogota, found their maximum to be 64 degrees centigrade. I found it at the same season only 59.2 degrees. Has the great earthquake of the 26th March, 1812, had an influence on the temperature of these springs? The able chemists above mentioned were, like myself, struck with the extreme purity of the hot waters that issue from the primitive rocks of the basin of Aragua. Those of Onoto, which flow at the height of 360 toises above the level of the sea, have no smell of sulphuretted hydrogen; they are without taste, and cannot be precipitated, either by nitrate of silver or any other re-agent. When evaporated they have an inappreciable residue which consists of a little silica and a trace of alkali; their temperature is only 44.5 degrees, and the bubbles of air which are disengaged at intervals are at Onoto, as well as in the thermal waters of Mariara, pure nitrogen. The waters of Mariara (244 toises) have a faint smell of sulphuretted hydrogen; they leave, by evaporation, a slight residuum, that yields carbonic acid, sulphuric acid, soda, magnesia and lime. The quantities are so small that the water is altogether without taste. In the course of my journey I found only the springs of Cumangillas hotter than the thermal waters of Las Trincheras: they are situated on the south of Porto Cabello. The waters of Comangillas are at the height of 1040 toises and are alike remarkable for their purity and their temperature of 96.3 degrees centigrade.), those of Las Trincheras (90.4 degrees) on its southern slope and those of Onoto and Mariara on its southern slope. The former issue from a granite with large grains, very regularly stratified; the latter from a rock of gneiss. What especially characterizes the northern chain is a summit which is not only the loftiest of the system of the mountains of Venezuela, but of all South America, on the east of the Andes. The eastern summit of the Silla of Caracas, according to my barometric measurement made in 1800, is 1350 toises high,* (* The Silla of Caracas is only 80 toises lower than the Canigou in the Pyrenees.) and notwithstanding the commotion which took place on the Silla during the great earthquake of Caracas, that mountain did not sink 50 or 60 toises, as some North American journals asserted. Four or five leagues south of the northern chain (that of Mariara, La Silla and Cape Codera) the mountains of Guiripa, Ocumare and Panaquire form the southern chain of the coast, which stretches in a parallel direction from Guigue to the mouth of the Rio Tuy, by the Guesta of Yusma and the Guacimo. The latitudes of the Villa de Cura and San Juan, so erroneously marked on our maps, enabled me to ascertain the mean breadth of the whole Cordillera of Venezuela. Ten or twelve leagues may be reckoned as the distance from the descent of the northern chain which bounds the Caribbean Sea, to the descent of the southern chain bounding the immense basin of the Llanos. This latter chain, which also bears the name of the Inland Mountains, is much lower than the northern chain; and I can hardly believe that the Sierra de Guayraima attains the height of 1200 toises.

The two partial chains, that of the interior, and that which runs along the coast, are linked by a ridge or knot of mountains known by the names of Altos de las Cocuyzas (845 toises) and the Higuerote (835 toises between Los Teques and La Victoria) in longitude 69 degrees 30 minutes and 69 degrees 50 minutes. On the west of this ridge lies the enclosed basin* of the lake of Valencia or the Valles de Aragua (* This basin contains a small system of inland rivers which do not communicate with the ocean. The southern chain of the litteral Cordillera of Venezuela is so depressed on the south-west that the Rio Pao is separated from the tributary streams of the lake of Tacarigua or Valencia. Towards the east the Rio Tuy, which takes its rise on the western declivity of the knot of mountains of Las Cocuyzas, appears at first to empty itself into the valleys of Aragua; but hills of calcareous tufa, forming a ridge between Consejo and Victoria, force it to take its course south-east.); and on the east the basin of Caracas and of the Rio Tuy. The bottom of the first-mentioned basins is between 220 and 250 toises high; the bottom of the latter is 460 toises above the level of the Caribbean Sea. It follows from these measures that the most western of the two longitudinal valleys enclosed by the littoral Cordillera is the deepest; while in the plains near the Apure and the Orinoco the declivity is from west to east; but we must not forget that the peculiar disposition of the bottom of the two basins, which are bounded by two parallel chains, is a local phenomenon altogether separate from the causes on which the general structure of the country depends. The eastern basin of the Cordillera of Venezuela is not shut up like the basin of Valencia. It is in the knot of the mountains of Las Cocuyzas, and of Higuerote, that the Serrania de los Teques and Oripoto, stretching eastward, form two valleys, those of the Rio Guayre and Rio Tuy; the former contains the town of Caracas and both unite below the Caurimare. The Rio Tuy runs through the rest of the basin, from west to east, as far as its mouth which is situated on the north of the mountains of Panaquire.

Cape Codera seems to terminate the northern range of the littoral mountains of Venezuela but this termination is only apparent. The coast forms a vast nook, thirty-five sea leagues in length, at the bottom of which is the mouth of the Rio Unare and the road of Nueva Barcelona. Stretching first from west to east, in the parallel of 10 degrees 37 minutes, this coast recedes at the parallel 10 degrees 6 minutes, and resumes its original direction (10 degrees 37 minutes to 10 degrees 44 minutes) from the western extremity of the peninsula of Araya to the eastern extremities of Montana de Paria and the island of Trinidad. From this dissection of the coast it follows that the range of mountains bordering the shore of the provinces of Caracas and Barcelona, between the meridian 66 degrees 32 minutes and 68 degrees 29 minutes (which I saw on the south of the bay of Higuerote and on the north of the Llanos of Pao and Cachipo), must be considered as the continuation of the southern chain of Venezuela and as being linked on the west with the Sierras de Panaquire and Ocumare. It may therefore be said that between Cape Codera and Cariaco the inland chain itself forms the coast. This range of very low mountains, often interrupted from the mouth of the Rio Tuy to that of the Rio Neveri, rises abruptly on the east of Nueva Barcelona, first in the rocky island of Chimanas, and then in the Cerro del Bergantin, elevated probably more than 800 toises, but of which the astronomical position and the precise height are yet alike unknown. On the meridian of Cumana the northern chain (that of Cape Codera and the Silla of Caracas) again appears. The micaceous slate of the peninsula of Araya and Maniquarez joins by the ridge or knot of mountains of Meapire the southern chain, that of Panaquire the Bergantin, Turimiquiri, Caripe and Guacharo. This ridge, not more than 200 toises of absolute height, has, in the ancient revolutions of our planet, prevented the irruption of the ocean, and the union of the gulfs of Paria and Cariaco. On the west of Cape Codera the northern chain, composed of primitive granitic rocks, presents the loftiest summits of the whole Cordillera of Venezuela; but the culminant points east of that cape are composed in the southern chain of secondary calcareous rocks. We have seen above that the peak of Turimiquiri, at the back of the Cocollar, is 1050 toises, while the bottoms of the high valleys of the convent of Caripe and of Guardia de San Augustin are 412 and 533 toises of absolute height. On the east of the ridge of Meapire the southern chain sinks abruptly towards the Rio Arco and the Guarapiche; but, on quitting the main land, we again see it rising on the southern coast of the island of Trinidad which is but a detached portion of the continent, and of which the northern side unquestionably presents the vestiges of the northern chain of Venezuela, that is, of the Montana de Paria (the Paradise of Christopher Columbus), the peninsula of Araya and the Silla of Caracas. The observations of latitude I made at the Villa de Cura (10 degrees 2 minutes 47 seconds), the farm of Cocollar (10 degrees 9 minutes 37 seconds) and the convent of Caripe (10 degrees 10 minutes 14 seconds), compared with the more anciently known position of the south coast of Trinidad (latitude 10 degrees 6 minutes), prove that the southern chain, south of the basins of Valencia and of Tuy* (* The bottom of the first of these four basins bounded by parallel chains is from 230 to 460 toises above, and that of the two latter from 30 to 40 toises below the present sea-level. Hot springs gush from the bottom of the gulf of the basin of Cariaco, as from the bottom of the basin of Valencia on the continent.) and of the gulfs of Cariaco and Paria, is still more uniform in the direction from west to east than the northern chain from Porto Cabello to Punta Galera. It is highly important to know the southern limit of the littoral Cordillera of Venezuela because it determines the parallel at which the Llanos or the savannahs of Caracas, Barcelona and Cumana begin. On some well-known maps we find erroneously marked between the meridians of Caracas and Cumana two Cordilleras stretching from north to south, as far as latitude 8 3/4 degrees, under the names of Cerros de Alta Gracia and del Bergantin, thus describing as mountainous a territory of 25 leagues broad, where we should seek in vain a hillock of a few feet in height.

Turning to the island of Marguerita, composed, like the peninsula of Araya, of micaceous slate, and anciently linked with that peninsula by the Morro de Chacopata and the islands of Coche and Cubagua, we seem to recognize in the two mountainous groups of Macanao and La Vega de San Juan traces of a third coast-chain of the Cordillera of Venezuela. Do these two groups of Marguerita, of which the most westerly is above 600 toises high, belong to a submarine chain stretching by the isle of Tortuga, towards the Sierra de Santa Lucia de Coro, on the parallel of 11 degrees? Must we admit that in latitude 11 1/4 and 12 1/2 degrees a fourth chain, the most northerly of all, formerly stretched out in the direction of the island of Hermanos, by Blanquilla, Los Roques, Orchila, Aves, Buen Ayre, Curacao and Oruba, towards Cape Chichivacoa? These important problems can only be solved when the chain of islands parallel with the coast has been properly examined. It must not be forgotten that a great irruption of the ocean appears to have taken place between Trinidad and Grenada,* and that no where else in the long series of the Lesser Antilles are two neighbouring islands so far removed from each other. (* It is affirmed that the island of Trinidad is traversed in the northern part by a chain of primitive slate, and that Grenada furnishes basalt. It would be important to examine of what rock the island of Tobago is composed; it appeared to me of dazzling whiteness; and on what point, in going from Trinidad northward, the trachytic and trappean system of the Lesser Antilles begins.) We observe the effect of the rotatory current in the direction of the coast of Trinidad, as in the coasts of the provinces of Cumana and Caracas, between Cape Paria and Punta Araya and between Cape Codera and Porto Cabello. If a part of the continent has been overwhelmed by the ocean on the north of the peninsula of Araya it is probable that the enormous shoal which surrounds Cubagua, Coche the island of Marguerita, Los Frailes, La Sola and the Testigos marks the extent and outline of the submerged land. This shoal or placer, which is of the extent of 200 square leagues, is well known only to the tribe of the Guayqueries; it is frequented by these Indians on account of its abundant fishery in calm weather. The Gran Placer is believed to be separated only by some canals or deep furrows of the bank of Grenada from the sand-bank that extends like a narrow dyke from Tobago to Grenada, and which is known by the lowering of the temperature of the water and from the sand-banks of Los Roques and Aves. The Guayquerie Indians and, generally speaking, all the inhabitants of the coast of Cumana and Barcelona, are imbued with an idea that the water of the shoals of Marguerita and the Testigos diminishes from year to year; they believe that, in the lapse of ages, the Morro do Chacopata on the peninsula of Araya will be joined by a neck of land to the islands of Lobos and Coche. The partial retreat of the waters on the coast of Cumana is undeniable and the bottom of the sea has been upheaved at various times by earthquakes; but these local phenomena, which it is so difficult to account for by the action of volcanic force, the changes in the direction of currents, and the consequent swelling of the waters, are very different from the effects manifested at once over the space of several hundred square leagues.

4. GROUP OF THE MOUNTAINS OF PARIME.

It is essential to mineralogical geography to designate by one name all the mountains that form one system. To attain this end, a denomination belonging to a partial group only may be extended over the whole chain; or a name may be employed which, by reason of its novelty, is not likely to give rise to homogenic mistakes. Mountaineers designate every group by a special denomination; and a chain is generally considered as forming a whole only when it is seen from afar bounding the horizon of the plains. We find the name of snowy mountains (Himalaya, Imaus) repeated in every zone, white (Alpes, Alb), black and blue. The greater part of the Sierra Parime is, as it were, edged round by the Orinoco. I have, however, avoided a denomination having reference to this circumstance, because the group of mountains to which I am about to direct attention extends far beyond the banks of the Orinoco. It stretches south-east, towards the banks of the Rio Negro and the Rio Branco, to the parallel of 1 1/2 degrees north latitude. The geographical name of Parime has the advantage of reviving recollections of the fable of El Dorado, and the lofty mountains which, in the sixteenth century, were supposed to surround the lake Rupunuwini, or the Laguna de Parime. The missionaries of the Orinoco still give the name of Parime to the whole of the vast mountainous country comprehended between the sources of the Erevato, the Orinoco, the Caroni, the Rio Parime* (a tributary of the Rio Branco) and the Rupunuri or Rupunuwini, a tributary of the Rio Essequibo. (* The Rio Parime, after receiving the waters of the Uraricuera, joins the Tacutu, and forms, near the fort of San Joacquim, the Rio Branco, one of the tributary streams of the Rio Negro.) This country is one of the least known parts of South America and is covered with thick forests and savannahs; it is inhabited by independent Indians and is intersected by rivers of dangerous navigation, owing to the frequency of shoals and cataracts.

The system of the mountains of Parime separates the plains of the Lower Orinoco from those of the Rio Negro and the Amazon; it occupies a territory of trapezoidal form, comprehended between the parallels of 3 and 8 degrees, and the meridians of 61 and 70 1/2 degrees. I here indicate only the elements of the loftiest group, for we shall soon see that towards south-east the mountainous country, in lowering, draws near the equator, as well as to French and Portuguese Guiana. The Sierra Parime extends most in the direction north 85 degrees west and the partial chains into which it separates on the westward generally follow the same direction. It is less a Cordillera or a continuous chain in the sense given to those denominations when applied to the Andes and Caucasus than an irregular grouping of mountains separated the one from the other by plains and savannahs. I visited the northern, western and southern parts of the Sierra Parime, which is remarkable by its position and its extent of more than 25,000 square leagues. From the confluence of the Apure, as far as the delta of the Orinoco, it is uniformly three or four leagues removed from the right bank of the great river; only some rocks of gneiss-granite, amphibolic slate and greenstone advance as far as the bed of the Orinoco and create the rapids of Torno and of La Boca del Infierno.* (* To this series of advanced rocks also belong those which pierce the soil between the Rio Aquire and the Rio Barima; the granitic and amphibolic rocks of the Vieja Guayana and of the town of Angostura; the Cerro de Mono on the south-east of Muitaco or Real Corono; the Cerro of Taramuto near the Alta Gracia, etc.) I shall name successively, from north-north-east to south-south-west, the different chains seen by M. Bonpland and myself as we approached the equator and the river Amazon. First. The most northern chain of the whole system of the mountains of Parime appeared to us to be that which stretches (latitude 7 degrees 50 minutes) from the Rio Arui, in the meridian of the rapids of Camiseta, at the back of the town of Angostura, towards the great cataracts of the Rio Carony and the sources of the Imataca. In the missions of the Catalonian Capuchins this chain, which is not 300 toises high, separates the tributary streams of the Orinoco and those of the Rio Cuyuni, between the town of Upata, Cupapui and Santa Marta. Westward of the meridian of the rapids of Camiseta (longitude 67 degrees 10 minutes) the high mountains in the basin of the Rio Caura only commence at 7 degrees 20 minutes of latitude, on the south of the mission of San Luis Guaraguaraico, where they occasion the rapids of Mura. This chain stretches westward by the sources of the Rio Cuchivero, the Cerros del Mato, the Cerbatana and Maniapure, as far as Tepupano, a group of strangely-formed granitic rocks surrounding the Encaramada. The culminant points of this chain (latitude 7 degrees 10 minutes to 7 degrees 28 minutes) are, according to the information I gathered from the Indians, situated near the sources of Cano de la Tortuga. In the chain of the Encaramada there are some traces of gold. This chain is also celebrated in the mythology of the Tamanacs; for the painted rocks it contains are associated with ancient local traditions. The Orinoco changes its direction at the confluence of the Apure, breaking a part of the chain of the Encaramada. The latter mountains and scattered rocks in the plain of the Capuchino and on the north of Cabruta may be considered either as the vestiges of a destroyed spur or (on the hypothesis of the igneous origin of granite) as partial eruptions and upheavings. I shall not here discuss the question whether the most northerly chain, that of Angostura and of the great fall of Carony, be a continuation of the chain of Encaramada. Third. In navigating the Orinoco from north to south we observe, alternately, on the east, small plains and chains of mountains of which we cannot distinguish the profiles, that is, the sections perpendicular to their longitudinal axes. From the mission of the Encaramada to the mouth of the Rio Qama I counted seven recurrences of this alternation of savannahs and high mountains. First, on the south of the isle Cucuruparu rises the chain of Chaviripe (latitude 7 degrees 10 minutes); it stretches, inclining towards the south (latitude 6 degrees 20 minutes to 6 degrees 40 minutes), by the Cerros del Corozal, the Amoco, and the Murcielago, as far as the Erevato, a tributary of the Caura. It there forms the rapids of Paru and is linked with the summits of Matacuna. Fourth. The chain of Chaviripe is succeeded by that of the Baraguan (latitude 6 degrees 50 minutes to 7 degrees 5 minutes), celebrated for the strait of the Orinoco, to which it gives its name. The Saraguaca, or mountain of Uruana, composed of detached blocks of granite, may be regarded as a northern spur of the chain of the Baraguan, stretching south-west towards Siamacu and the mountains (latitude 5 degrees 50 minutes) that separate the sources of the Erevato and the Caura from those of the Ventuari. Fifth. The chain of Carichana and of Paruaci (latitude 6 degrees 25 minutes), wild in aspect, but surrounded by charming meadows. Piles of granite crowned with trees and insulated rocks of prismatic form (the Mogote of Cocuyza and the Marimaruta or Castillito of the Jesuits) belong to this chain. Sixth. On the western bank of the Orinoco, which is low and flat, the Peak of Uniana rises abruptly more than 3000 feet high. The spurs (latitude 5 degrees 35 minutes to 5 degrees 40 minutes) which this peak sends eastward are crossed by the Orinoco in the first Great Cataract (that of Mapura or the Atures); further on they unite together and, rising in a chain, stretch towards the sources of the Cataniapo, the rapids of Ventuari, situated on the north of the confluence of the Asisi (latitude 5 degrees 10 minutes) and the Cerro Cunevo. Seventh. Five leagues south of the Atures is the chain of Quittuna, or of Maypures (latitude 15 degrees 13 minutes), which forms the bar of the Second Great Cataract. None of those lofty summits are situated on the west of the Orinoco; on the east of that river rises the Cunavami, the truncated peak of Calitamini and the Jujamari, to which Father Gili attributes an extraordinary height. Eighth. The last chain of the south-west part of the Sierra Parime is separated by woody plains from the chain of Maypures; it is the chain of the Cerros de Sipapo (latitude 4 degrees 50 minutes); an enormous wall behind which the powerful chief of the Guaypunabi Indians intrenched himself during the expedition of Solano. The chain of Sipapo may be considered as the beginning of the range of lofty mountains which bound, at the distance of some leagues, the right bank of the Orinoco, where that river runs from south-east to north-west, between the mouth of the Ventuari, the Jao and the Padamo (latitude 3 degrees 15 minutes). In ascending the Orinoco, above the cataract of Maypures, we find, long before we reach the point where it turns, near San Fernando del Atabapo, the mountains disappearing from the bed of the river, and from the mouth of the Zama there are only insulated rocks in the plains. The chain of Sipapo forms the south-west limit of the system of mountains of Parime, between 70 1/2 and 68 degrees of longitude. Modem geologists have observed that the culminant points of a group are less frequently found at its centre than towards one of its extremities, preceding, and announcing in some sort, a great depression* of the chain. (* As seen in Mont Blanc and Chimborazo.) This phenomenon is again observed in the group of the Parime, the loftiest summits of which, the Duida and the Maraguaca, are in the most southerly range of mountains, where the plains of the Cassiquiare and the Rio Negro begin.

These plains or savannahs which are covered with forests only in the vicinity of the rivers do not, however, exhibit the same uniform continuity as the Llanos of the Lower Orinoco, of the Meta and of Buenos Ayres. They are interrupted by groups of hills (Cerros de Daribapa) and by insulated rocks of grotesque form which pierce the soil and from a distance fix the attention of the traveller. These granitic and often stratified masses resemble the ruins of pillars or edifices. The same force which upheaved the whole group of the Sierra Parime has acted here and there in the plains as far as beyond the equator. The existence of these steeps and sporadic hills renders it difficult to determine the precise limits of a system in which the mountains are not longitudinally ranged as in a vein. As we advance towards the frontier of the Portuguese province of the Rio Negro the high rocks become more rare and we no longer find the shelves or dykes of gneiss-granite which cause rapids and cataracts in the rivers.

Such is the surface of the soil between 68 1/2 and 70 1/2 degrees of longitude, between the meridian of the bifurcation of the Orinoco and that of San Fernando de Atabapo; further on, westward of the Upper Rio Negro, towards the source of that river, and its tributary streams the Xie and the Uaupes (latitude 1 to 2 1/4 degrees, longitude 72 to 74 degrees) lies a small mountainous tableland, in which Indian traditions place a Laguna de oro, that is, a lake surrounded with beds of auriferous earth.* (* According to the journals of Acunha and Fritz the Manao Indians (Manoas) obtained from the banks of the Yquiari (Iguiare or Iguare) gold of which they made thin plates. The manuscript notes of Don Apollinario also mention the gold of the Rio Uaupes. La Condamine, Voyage a l'Amazone. We must not confound the Laguna de Oro, which is said to be found in going up the Uaupes (north latitude 0 degrees 40 minutes) with another gold lake (south latitude 1 degree 10 minutes) which La Condamine calls Marahi or Morachi (water), and which is merely a tract often inundated between the sources of the Jurubech (Urubaxi) and the Rio Marahi, a tributary stream of the Caqueta.) At Maroa, the most westerly mission of the Rio Negro, the Indians assured me that that river as well as the Inirida (a tributary of the Guavare) rises at the distance of five days' march, in a country bristled with hills and rocks. The natives of San Marcellino speak of a Sierra Tunuhy, nearly thirty leagues west of their village, between the Xie and the Icanna. La Condamine learned also from the Indians of the Amazon that the Quiquiari comes from a country of mountains and mines. Now, the Iquiari is placed by the French astronomer between the equator and the mouth of the Xie (Ijie), which identifies it with the Iguiare that falls into the Icanna. We cannot advance in the geologic knowledge of America without having continually recourse to the researches of comparative geography. The small system of mountains, which we may provisionally call that of the sources of the Rio Negro and the Uaupes, and the culminant points of which are not probably more than 100 or 120 toises high, appears to extend southward to the basin of Rio Yupura, where rocky ridges form the cataracts of the Rio de los Enganos and the Salto Grande de Yupura (south latitude 0 degrees 40 minutes to north latitude 0 degrees 28 minutes), and the basin of the Upper Guaviare towards the west. We find in the course of this river, from 60 to 70 leagues west of San Fernando del Atabapo, two walls of rocks bounding the strait (nearly 3 degrees 10 minutes north latitude and 73 3/4 degrees longitude) where father Maiella terminated his excursion. That missionary told me that, in going up the Guaviare, he perceived near the strait (angostura) a chain of mountains bounding the horizon on the south. It is not known whether those mountains traverse the Guaviare more to the west, and join the spurs which advance from the eastern Cordillera of New Grenada, between the Rio Umadea and the Rio Ariari, in the direction of the savannahs of San Juan de los Llanos. I doubt the existence of this junction. If it really existed, the plains of the Lower Orinoco would communicate with those of the Amazon only by a very narrow land-strait, on the east of the mountainous country which surrounds the source of the Rio Negro: but it is more probable that this mountainous country (a small system of mountains, geognostically dependent on the Sierra Parime) forms as it were an island in the Llanos of Guaviare and Yupura. Father Pugnet, Principal of the Franciscan convent at Popayan, assured me, that when he went from the missions settled on the Rio Caguan to Aramo, a village situated on the Rio Guayavero, he found only treeless savannahs, extending as far as the eye could reach. The chain of mountains placed by several modern geographers, between the Meta and the Vichada, and which appears to link the Andes of New Grenada with the Sierra Parime, is altogether imaginary.

We have now examined the prolongation of the Sierra Parime on the west, towards the source of the Rio Negro: it remains for us to follow the same group in its eastern direction. The mountains of the Upper Orinoco, eastward of the Raudal of the Guaharibos (north latitude 1 degree 15 minutes longitude 67 degrees 38 minutes), join the chain of Pacaraina, which divides the waters of the Carony and the Rio Branco, and of which the micaceous schist, resplendent with silvery lustre, figures so conspicuously in Raleigh's El Dorado. The part of that chain containing the sources of the Orinoco has not yet been explored; but its prolongation more to the east, between the meridian of the military post of Guirior and the Rupunuri, a tributary of the Essequibo, is known to me through the travels of the Spaniards Antonio Santos and Nicolas Rodriguez, and also by the geodesic labours of two Portuguese, Pontes and Almeida. Two portages but little frequented* are situated between the Rio Branco and the Rio Essequibo, south of the chain of Pacaraina; they shorten the land-road leading from the Villa del Rio Negro to Dutch Guiana. (* The portages of Sarauru and the lake Amucu.) On the contrary, the portage between the basin of the Rio Branco and that of the Carony crosses the summit of the chain of Pacaraina. On the northern slope of this chain rises the Anocapra, a tributary of the Paraguamusi or Paravamusi; and on the southern slope, the Araicuque, which, with the Uraricapara, forms the famous Valley of Inundations, above the destroyed mission of Santa Rosa (latitude 3 degrees 46 minutes, longitude 65 degrees 10 minutes). The principal Cordillera, which appears of little breadth, stretches on a length of 80 leagues, from the portage of Anocapra (longitude 65 degrees 35 minutes) to the left bank of the Rupunuri (longitude 61 degrees 50 minutes), following the parallels of 4 degrees 4 minutes and 4 degrees 12 minutes. We there distinguish from west to east the mountains of Pacaraina, Tipique, Tauyana, among which rises the Rio Parime (a tributary of the Uraricuera), Tubachi, Christaux (latitude 3 degrees 56 minutes, longitude 62 degrees 52 minutes) and Canopiri. The Spanish traveller, Rodriguez, marks the eastern part of the chain by the name of Quimiropaca; but preferring to adopt general names, I continue to give the name of Pacaraina to the whole of this Cordillera which links the mountains of the Orinoco to the interior of Dutch and French Guiana, and which Raleigh and Keymis made known in Europe at the end of the 16th century. This chain is broken by the Rupunuri and the Essequibo, so that one of their tributary streams, the Tavaricuru, takes its rise on the southern declivity, and the other, the Sibarona, on the northern. On approaching the Essequibo, the mountains are more developed towards the south-east, and extend beyond 2 1/2 degrees north latitude. From this eastern branch of the chain of Pacaraina the Rio Rupunuri rises near the Cerro Uassari. On the right bank of the Rio Branco, in a still more southern latitude (between 1 and 2 degrees north) is a mountainous territory in which the Caritamini, the Padaviri, the Cababuri (Cavaburis) and the Pacimoni take their source, from east to west. This western branch of the mountains of Pacaraina separates the basin of Rio Branco from that of the Upper Orinoco, the sources of which are probably not found east of the meridian of 66 15 minutes: it is linked with the mountains of Unturan and Yumariquin, situated south-east of the mission of Esmeralda. Thence it results that, while on the west of the Cassiquiare, between that river, the Atabapo, and the Rio Negro, we find only vast plains, in which rise some little hills and insulated rocks; real spurs stretch eastward of the Cassiquiare, from north-west to south-east, and form a continued mountainous territory as far as 2 degrees north latitude. The basin only, or rather the transversal valley of the Rio Branco, forms a kind of gulf, a succession of plains and savannahs (campos) several of which penetrate from south to north, into the mountainous land between the eastern and western branches of the chain of Pacaraina, to the distance of eight leagues north of the parallel of San Joaquin.