Witwatersrand

Witwatersrand, rocky uplift in northeastern South Africa. Also known as the Rand, it is the most productive gold-mining district in the world and the chief industrial region of South Africa. Witwatersrand consists of a series of parallel ridges running east and west in the Republic of South Africa. These gold-bearing ridges are 100 km (60 mi) long, have a maximum width of 40 km (25 mi), and reach an elevation of 600 m (2,000 ft) above sea level. Witwatersrand means “ridge of white waters” in Afrikaans. This rock formation creates the watershed between the Vaal and the Olifantsrivier, which empty into the Atlantic and Indian oceans, respectively. Johannesburg is the largest city in the region.

The Witwatersrand ridges are honeycombed with mines. Mineshaft openings in this landscape are surrounded by white mountains of rock that was crushed for mineral wealth and then abandoned as detritus from prospectors’ quests for gold. Witwatersrand also contains many uranium, manganese, and coal mines. Other industrial establishments in the region include the Germiston gold refinery (the largest in the world), foundries, engineering shops, and cement plants. Many service enterprises are supported by the region’s large mining-oriented population centers.

Surface gold was discovered in Witwatersrand in 1884, and active mining operations began in 1886, the same year in which Johannesburg was founded as a gold-mining settlement. Several years passed before prospectors discovered that the gold deposits extended deep into the Earth’s crust—far beyond their richest hopes. The main Witwatersrand gold reef was discovered in 1889 at a depth of 177 m (581 ft). In a matter of years, gold mines in the region extended more than 2 km (1.2 mi) into the Earth’s crust.

The great extent of the deposits, both laterally and in depth, has permitted exploitation of the area on a large and profitable scale. In the 1930s, following the abandonment by many countries of the gold standard and the initiation by the United States of unlimited gold purchases, the ore was mined at a depth of 3,700 m (12,000 ft); subsequently, the deepest workings averaged 2,700 m (9,000 ft) in depth. These deep-level mines have temperatures much warmer than regional surface temperatures. Expensive cooling and ventilation systems must be installed in the mines so miners can tolerate this extreme subterranean environment.