Witwatersrand

Witwatersrand (Afrikaans, “ridge of white waters”), rocky uplift in north-eastern South Africa. Also known as the Rand, it is the most productive gold-mining district in the world. The uplift is about 100 km (60 mi) long in an east-west direction, has a maximum width of about 40 km (25 mi), and reaches an elevation of more than 610 m (2,000 ft) above the surrounding plateau area. The rock formation creates the watershed between the Vaal and Olifantsrivier rivers, which drain into the Atlantic and Indian oceans respectively. Surface gold was discovered in the region in 1884, and active mining operations began in 1886, the same year that Johannesburg, the chief city of the Rand, was founded as a gold-mining settlement. The main gold reef was discovered in the region in 1889, at a depth of 177 m (581 ft).

The great extent of the deposits, both laterally and in depth, has permitted exploitation of the area on a large and very profitable scale. In the 1930s, following the abandonment by most countries of the gold standard and the initiation by the United States of unlimited gold purchases, the ore was mined at a depth of about 3,360 m (12,000 ft); subsequently, the deepest workings averaged some 2,745 m (9,000 ft) in depth.

Two of the deepest mines, the Crown and the Robinson Deep, contain shafts of some 3,000 m (10,000 ft) into the earth. These mines are as much as 10° C (50° F) warmer than surface temperatures. Expensive cooling and ventilation systems must be installed in the mines so that the miners can tolerate this extreme subterranean environment. But they yield great quantities of gold—in 1960 the region supplied one third of the world's total gold production.

The Witwatersrand ridges are honeycombed with mines. Shaft heads are surrounded by white mountains of rock crushed for mineral wealth and then abandoned as detritus from prospectors' quests for gold. Witwatersrand also contains many mines to extract valuable deposits of uranium, manganese, and coal. Industrial establishments include the Germiston gold refinery (the largest in the world), foundries, engineering shops, and cement plants.