English: The position of the Kaapvaal Craton (khaki coloured area) beneath the South African landscape, and the shrunken, shallow Witwatersrand Sea (light blue) at the time that the gold was deposited in the broad, river deltas of 6 rivers that flowed into that sea, depositing all their heavier materials (cobbles, gold, uranium iron pyrite etc.) in the braided rivers of the deltas.Most of these gold deposits are deep under the South African surface, but form outcrops (at the surface) south of the Johannesburg City Centre.