Guiana Highlands, mountainous tableland, c.1,200 mi (1,930 km) long and from 200 to 600 mi (322–966 km) wide, N South America, bounded by the Orinoco and Amazon river basins, and by the coastal lowlands of the Guianas. It is located in SE Venezuela, Guyana, Suriname, French Guiana, and N Brazil. The Pacaraima Mts., which culminate in Mt. Roraima (9,219 ft/2,810 m high) on the Venezuela–Guyana–Brazil border, form the highest section of the highlands. Geologically, the Guiana Highlands is a shield—a stable mass of Precambrian rock—and is related to the Brazilian Highlands. It consists of vast plateaus of ancient crystalline rocks overlaid by geologically recent sandstone and lava caps. The tablelands rise one after another, like gargantuan steps, in sheer escarpments hundreds to thousands of feet high. Numerous rivers, fed by heavy rainfall, rise in the highlands and pour over the edges to create deep gorges and magnificent waterfalls. Angel Fall (3,212 ft/979 m high) in Venezuela is the world's highest waterfall. The sparsely populated region, romantically depicted in W. H. Hudson's Green Mansions, is famous for the exuberance of its semideciduous tropical rain forests and for its rich fauna, including many varieties of brilliantly colored tropical birds. Its inaccessibility is attested by the discovery in the mid-1900s of the headwaters of the Orinoco River in the southwestern section and of a hitherto unknown indigenous tribe of tall people, the Panares. The crystalline rocks of the Guiana Highlands yield gold and diamonds. Large deposits of iron ore, manganese, and bauxite have been made accessible by new roads and railroads, but the enormous potential wealth of the highlands is still largely untapped because of the dense cover of vegetation. The region has great hydroelectric-power potential that could form the base for industrial development. The highlands remains one of the world's few frontiers although it is yielding to the development process that has transformed Santo Tomé de Guayana, Venezuela, into the region's chief industrial center and the gateway to the interior.