82 SOUTH AMERICA— THE ANDES EEGIONS. 



irregular ranges which skirt the right bank of the middle Orinoco along its great 

 beud. Here is situated the famous Cerro Duida (7,125 feet), a wooded pyramid 

 which is visible for an immense distance along the mainstream, and which 

 dominates the ramifying waters between the Orinoco and the Cassiquiare. It 

 has been called a volcano from the flitting flames often seen dancing above its 

 forest- clad slopes, although, from the descriptions of the natives, these flames 

 would seem to be merely will-o'-the-wisps. 



Duida is overtopped by Mount Maraguaca (Maravaca), which rises farther 

 inland to a height of 8,230 feet, while Maparana and the Cerro de Neiva in the 

 north-west are respectively 7,180 and 6,030 feet high. Beyond the deep valley 

 of the Rio Ventuari occur other lofty peaks, such as the Yamari (7,420), and the 

 Cunavana (6,180), besides various mountains whose spurs rise in towers, steps, or 

 abrupt slopes above the Orinoco, . To the same orographic sj^stem also belong a 

 few isolated eminences scattered over the llanos on the west side of the river. Of 

 these the highest is the peak of tJniana (1,900 feet), which is connected with the 

 uplands on the opposite side by the granitic Atures reefs, over which the Orinoco 

 descends in a series of rapids. Viewed as a whole, the mountains of the Parirna 

 system are distinguished by their relative isolation and broken character ; they 

 rise in the midst of the plains or of the lower grounds, without presenting any 

 well-defined continuous ridges. 



In the section of Venezuela comprised between the Orinoco, the Caura valley, 

 and the divide towards Guiana the country is everywhere hilly, and here and there 

 presents a few summits exceeding 3,000 feet in height. Such are Chanaro (5,480 

 feet), Turagua (6,000), and Tacuto (3,440), all rising above the east side of the 

 Caura valley. The other crests of Venezuelan Guiana, which are disposed in the 

 direction from south-east to north-west in a line with the axis of the Sierra Parima, 

 scarcely anj'where exceed 3,000 feet, except at the converging point of the Orinoco, 

 Amazons, and Essequibo basins, where Roraima, one of the great summits of the 

 Guiana region, attains an altitude of 7,400 feet. Although not penetrating into 

 the aerial zone of snows and glaciers, no mountain presents a more formidable 

 aspect. It forms an enormous mass of pink sandstone rising sheer above a vast 

 region of terraces and verdant valleys. Its vertical walls, averaging about 1,600 

 feet, are everywhere flanked at their base by accumulated masses of débris, forming 

 a long talus, which encloses the perpendicular upper cliffs on all sides. Seen 

 from below, the topmost platform of this frowning fortress, some three or four 

 miles in extent, seems to be perfectly level, although in reality strewn with 

 huge boulders resulting from the disintegration of the older strata. 



Other mountains in the district present a somewhat similar aspect, though on 

 a much smaller scale, and one of them, the " Crystal Mountain," is strewn with 

 crystalline quartz, all that now remains of vanished rocks. Obviously Roraima 

 was formerly part of an elevated tableland, which has been gradually isolated by 

 a process of cleavage and erosive action. It survives to present times as a superb 

 witness to former geological conditions. Streams have their rise on the upper 

 platform, over the edge of which they fall in cascades, draping the pink escarp- 



