As already defined, the Guayana Highlands include the whole of that vast, more or less unexplored, tract of Venezuela lying on the right bank of the Orinoco and round the head-waters of that river. The area is primarily one huge elevated plateau about 1,000 feet or more above the sea, and from this rise a few principal mountain ranges, with some peaks over 8,000 feet high, while smaller hills and chains link up the larger systems. The highest ground is found on the Brazilian frontier, beginning at Mount Roraima (8,500 feet), where the three boundaries of Venezuela, British Guiana, and Brazil meet, and extends thence in the Sierras Pacaraima and Parima westward and southward to the head-waters of the Orinoco. From Roraima the Orinoco-Cuyuni watershed extends northward within Venezuela, along the Sierras Rincote and Usupamo and the Highlands of Puedpa, to the Sierra Piacoa, and thence south-east along the Sierra Imataca to the British limits again. The Sierra Maigualida forms the watershed between the Caura and the Ventuari.
The whole area, which amounts to some 204,600 square miles, is well watered by the upper Orinoco and the Ventuari, with the other great tributaries, the Cuchivero, Caura, Aro, Caroni, and their affluents. Large as these rivers are, they are so broken by rapids that travel along them is only possible for much of their length in small portable craft, and even then the passage is fraught with danger. Save for the districts in the immediate neighbourhood of the Orinoco, and scattered areas elsewhere, the whole region is thickly covered with forests of valuable timber, containing rubber, tonka-beans, brazil-nuts, copaiba, and all the varied natural produce of the South American tropics.
The great plains or Llanos of the Orinoco extend from the banks of the Meta in a broad arc parallel to the course of the Orinoco along its left bank. Westward they are bounded by the Cordillera of Mérida, and northward by the Cordillera of Carácas and the hills of Sucre, but between these ranges, at Barcelona, they virtually reach the sea for a short distance. To the east they merge into the low-lying tract of the Orinoco Delta. The total area of the Llanos proper is in the neighbourhood of 108,300 square miles, so that we have in these two thinly populated tracts about 80 per cent. of the territory of the republic.
Vast areas of the Llanos remain, for all practical purposes, still unexplored, and their general character can only be inferred from that of the regions bordering on the “roads.” The typical areas are wide grass plains, often stretching to the horizon on all sides without a break, but generally interrupted by little groups of palms and small trees, especially near the banks of the rivers. At some four or five points near the northern edge there are great forests or selvas, relics possibly of an earlier, more extensive woodland.
The elevation of the Llanos ranges up to 650 feet, and more than this in the mesas of the central region, these being gravel-capped plateaux, of varying extent, beginning in the west with the Mesa de Santa Clara, northward of Caicara, and extending thence in a continuous series eastward and northward to form the watershed between the Orinoco and the Unare-Aragua basin, which drains into the Caribbean Sea west of Barcelona. The lowest part of the Llanos is situated westward of this chain of tablelands, in the valley of the Portuguesa, the lower part of which has large tracts less than 300 feet above sea-level. East of the Mesa de Guanipa the ground falls comparatively rapidly to the Delta.
PENINSULA OF PARIA FROM TRINIDAD.
IN THE DELTA.
While severe drought is experienced over much of the Llano region in summer, the heavy rains, particularly in the western districts, produce floods over the low-lying plains, the mesas being dry at all times. The whole area is traversed by numerous streams and rivers, which rise either on the southern slopes of the Cordillera or in the mesas. North of the Meta, in addition to the large number of smaller streams which here and there broaden out into marshy lakes or cienagas, we have the navigable rivers Arauca (the main waterway to eastern Colombia) and Apure, flowing from the Andes to the Orinoco in an easterly direction. The Apure receives many tributaries on its left bank from the Venezuelan Andes, most important of which are the Portuguesa, rising in the plains of the same name south of Barquisimeto and joining the Apure at San Fernando, and the Guárico, whose mouth is east of the same town, flowing from south of Carácas through the State to which it gives its name, and receiving from the east the waters of the Orituco, whose source is less than thirty miles from the coast in longitude 66°. Of the Orinoco tributaries from the north beyond the Apure the most important is the Manapire, all the streams east of this rising in the mesas and having but short courses. The greater part of the eastern Llanos drains northward by the Unare and Aragua into the Caribbean Sea. A few large rivers rise on the east of the mesas, but flow for short distances only through the plains, emptying, not into the Orinoco itself but the caños of the Delta. This last-mentioned region of inundated forest, savannah and mangrove swamp, occupies about 11,500 square miles, bringing the total area of the central plains up to 119,800 square miles.