S57 



AXDES. 



ANDES. 



358 



Farther north is the Pass of Quindiu, which skirts the Nevado de 

 Tolima, and leads from Santa Fe' de Bogota through the town of 

 Ibague, in the valley of the Magdalena, to Cartago . on the Cauca. Its 

 highest part is 11,493 feet above the sea. 



The Eastern Cordillera extends over a larger surface than the two 

 other ranges ; throughout the greater part of ita length it forms the 

 watershed between the Orinoco and the Magdalena, and where it divides 

 near 7 N. lat. its branches divide the basins of these rivers from that 

 of the lake of Maracaybo. From 2 N. lat. the range runs north-north- 

 east to 7 N. lat., and then turns north-east to its termination in the 

 Paramo de Rosas, between 9 and 10 N. lat. and near 70" W. long. 

 At this place it is connected with a coast-range (Sierra de la Costa), 

 which extends along the shore of the Caribbean Sea and eastward to 

 the gulf of Paria, and which by some is considered as a portion of the 

 Andes; but in mass, direction, elevation, and character, it differs 

 altogether from the Andes, and must be considered as a separate 

 range. The width of the Eastern Cordillera of the Northern Andes 

 varies greatly in different parts. Between 2 and 4 N. lat. it rises 

 like a wall, with steep slopes on both sides, and a width of 40 to 50 

 miles. North of 4 N. lat. the eastern declivity continues in a straight 

 line without offsets, but along the western side of the range lies a widely 

 extended terrace, the western edge of which approaches the Magdalena, 

 between 4 and 7 N. lat. ; and in this part the total width may be 100 

 miles. This terrace runs farther north to the very termination of the 

 range, but in these parts it is more narrow, so that north of 7 the 

 whole width of the mountains does not exceed 70 or 80 miles. The 

 height of this range is much more uniform than that of the two other 

 chains. In almost its whole extent it rises above the region of trees, 

 and ita mean elevation is between 12,000 and 13,000 feet above the 

 sea level But it rises very rarely into peaks, and only two of these 

 attain the snow-line, the Nevado de Chita (near 3 50' N. lat.) and the 

 Nevado de Merida or Mucuchies (8 12' N. lat.). 



The terrace on the western slope of the range rises in the south to 

 about two-thirds of the height of the range, the Plain of Bogota being 

 8958 feet above the sea. Farther north it is even higher, and probably 

 not much below 10,000 feet, but north of 6 N. lat. it sinks much 

 lower, in some parts to 4000 feet, except where it is traversed by the 

 Sierra de Ocana, which branches off near 7 N. lat., 78 W. long., and 

 forms part of the watershed between the lake of Maraeaybo and the 

 Magdalena. This chain does not exceed 8000 or 9000 feet in height, 

 and is much lower towards its northern extremity. The southern 

 Mid more elevated districts of the Cordillera abound in European 

 cereals and fruits, and the northern are rich in inter-tropical products. 

 Until lately it was thonght that there existed no volcano in the Eastern 

 Andes of New Granada, but it is now known that there is one not far 

 from their southern extremity (which forms the watershed between 

 the Amazonas and the Magdalena), near the Rio Fragua, a feeder of 

 the Japura. 



Three roads cross the Eastern Andes of Nueva Granada. The 

 most southern leads by the Pass of Toxillo, 12,000 feet high, near 

 6 30', from the llanos of Casinare to the town of Tunja on the 

 terrace west of the range. The great road which leads from Caracas 

 in Venezuela to Santa Fe" de Bogota, crosses the Paramo de Almosadero 

 (12,850 feet), near 7 N. lat. The third road crosses the chain near 

 the Nevado de Mucuchies, and unites the towns of Merida and 

 Varinas. 



ffntno-Lint and Scenery on the Anda. Respecting the limit of 

 perpetual snow there occur great anomalies on the Andes. Humboldt 

 had-, after numerous observations, established that the snow-line 

 occured on the Equatorial Andes at an elevation of 15,748 feet above 

 the sea, and it was reasonably supposed that it gradually descended 

 lower as the range proceeded farther south. But Mr. Pentland 

 found, that on the Bolivian Andes (between 16 and 18 S. lat.) it was 

 at 17,100 feet. In central Chili (33 8. lat.), Gillies found the snow- 

 line to be 1 4,500 to 15,000 feet high. Darwin, who had an opportunity 

 of observing it on the Patagonian Andes, found that on them it rose 

 hardly to more than 6000 feet above the level of the sea, and hence 

 he infers, that near 37 S. lat. the snow-line undergoes an extraordinary 

 flexure, which is also confirmed by the account of Pbppig, according 

 to which that line on the Volcano de Antuco can hardly be less than 

 12,000 feet above the sea. Darwin attributes the great flexure of the 

 snow-line, between 33 and 41" 8. lat, to the extreme dryness of the 

 atmosphere north of 87 S. lat., and to the excess of moisture south 

 of that parallel. But it would seem that the elevation of the snow- 

 line above the sea level is much more affected by localities than has 

 been supposed, for Mr. Pentland found that on the Andes of Vilcafiota 

 (14 S3 1 ) it rose only to 15,800 feet, whilst on Mount Incajo (15 580 

 it occurred at an elevation of 17,1 00 feet. Perhaps the currents of 

 hot air frequently experienced in the higher Andes, and not yet 

 accounted for, may contribute to cause the variation of the snow-line. 



The higher regions of the Andes present themselves under three 

 different forms. The active volcanoes, such as C'otopaxi, which have 

 only one crater of vast dimensions, are conical mountains, with 

 summits more or less truncated. Those which have been torn by a 

 long succession of eruptions have a jagged outline, being composed of 

 numerous sharp points, like what are called needles in the Alps. The 

 third is the rounded form, like Chimborazo, the most majestic of all, 

 which, when seen from the Pacific in a clear state of the atmosphere, 



stands prominently out from all the surrounding mountains, and 

 towers proudly on the crest of the Andes, like the dome of St. Peter's 

 looking down upon -the ancient monuments of Rome. The Andes 

 appear as a chain only when seen from a distance. When we are 

 placed within the range, as in the table-land of Quito, we see an 

 assemblage of insulated mountains rising from the plateau. Thus all 

 those volcanic peaks, such as Pichincha, Cayambe, and Cotopaxi, 

 although they have separate names, constitute for more than half 

 their height one mass ; but they appear to the inhabitants of the 

 table-land of Quito as distinct mountains rising out of a plain. The 

 great elevation of such table-lands makes it difficult to believe the 

 height of the mountains to be so considerable. Thus Chimborazo is 

 273 feet less in elevation above the plateau from which it rises than 

 the summit of Mont Blanc is above the valley of Chamouni, and 

 mountains which would astonish us by their height if they rose at 

 once from the sea-shore, look like low hills on the Cordilleras. 

 Humboldt and Bonpland endeavoured, but without success, to reach 

 the summit of Chimborazo ; they ascended however to the height of 

 19,280 feet. 



Among the majestic and varied scenes which the Cordilleras present, 

 says Humboldt, the valleys produce the most striking effects upon the 

 imagination of the European traveller. The enormous height of the 

 mountains cannot be seen as a whole except at a considerable distance, 

 and when we are in the plains which extend from the coast to the 

 foot of the central chain. The table-lands which surround the 

 summits covered with perpetual snow are, for the most part, elevated 

 from 8000 to 10,000 feet 'above the level of the ocean. That 

 circumstance diminishes to a certain extent the impression of grandeur 

 produced by the colossal masses of Chimborazo, Cotopaxi, and 

 Antiimna, when seen from the table-lands of Riobamba and Quito. 

 But it is not with the valleys as with the mountains ; deeper and 

 narrower than those of the Alps and Pyrenees, the valleys of the 

 Cordilleras present situations so wild as to fill the mind with fear and 

 admiration. They are formed by vast rents, clothed with a vigorous 

 vegetation, and of such a depth that Vesuvius might be placed in 

 them without overtopping the nearest heights. Thus, the sides of the 

 celebrated valleys of Chota and Cutaco are respectively 4875 and 4225 

 feet in perpendicular height ; their breadth does not exceed 2600 feet. 

 The deepest valley in Europe is that of Ordesa in the Pyrenees, a 

 part of Monte Perdito ; but this is only about 3200 feet deep. 



The Andes contain the sources of the greatest rivers in the world, 

 the Amazonas and La Plata, besides many others of considerable 

 extent, such as the Magdalena and Orinoco ; but on the western side 

 of the mountains there is no river of any magnitude. 



Geological Structure and Mineral Wealth of the Andes. The Andes 

 are remarkable for the great development of volcanic force which 

 they exhibit, and which finds its vents in linear groups of active 

 volcanoes. These ignivomous groups doubtless have a common 

 origin, though they are separated by some hundreds of miles. Exclu- 

 sive of these intervals the line of volcanic action extends over a 

 length little short of 2000 miles, and lies in the main (chiefly in the 

 western) ranges of the system : on the table-lands of the Andes, 

 which constitute the intervals between the groups, and on the vast 

 plains east of the system, no trace of volcanic action is found. The 

 whole region of the Andes is subject to tremendous earthquakes. 



With regard to the geological structure of this vast mountain 

 system little more can be done here than to enumerate the names of 

 the prevailing masses of rock. Granite forms the base of all the 

 South American continent, and it is found abundantly in the Southern 

 and Patagonian Andes at great elevations ; but in Peru and Quito 

 Humboldt says that he never saw it at a greater height than 11,500 

 feet above the sea. Gneiss, and more commonly mica-schist are found 

 associated with granite. Quartz also, containing gold, mercury, spec j- 

 lar iron, and sulphur, is extensively developed ; on the western slopes of 

 the Peruvian Andes layers of it 6000 feet thick extend several leagues 

 in length. On the Andes generally and the eastern table-lands red 

 sandstone of different periods covers a vast area, and has in connection 

 with it coal, which at Huenca in Pen: is found at the height of 14,750 

 feet above the sea. Porphyry of different ages and varieties is found 

 all over the Andes, on the slopes and crests of the mountains, in 

 layers of great thickness ; which, with their purple, red, and brown 

 tints, exposed to view in the precipitous faces of the rocks (especially 

 in the Chilian part of the chain), give great variety to the colouring 

 of the Andes, and contrast strongly with the snow on the crest of the 

 mountains. Trachyte also is very abundant, many of the loftiest 

 parts of the chain and all the great dome-shaped summits being 

 formed of it. The masses of this rock that occur on Chimborazo and 

 Pichincha are of enormous thickness, exceeding 16,000 feet. In the 

 neighbourhood of volcanoes the western slopes of the Andes are deeply 

 covered with lava, tufa, obsidian, and other volcanic rocks. The 

 Western Cordillera of the Bolivian Andes is entirely composed of 

 such products, while the Eastern Cordillera consists of syenite, mica- 

 schist, porphyry, and sandstone, with gypsum, oolitic limestone, and 

 rock-salt. 



Sea-shells of different geological periods are found at various eleva- 

 tions, especially in" the southern part of the system of the Andes, 

 giving evidence that this part of the Andes, at all events, is the result 

 of frequent upheavings. The silicified stems of large trees found in 



