ABSTRACT
The major gold deposits in South Africa are found in the gold reefs of the Witwatersrand System, a 500 kilometre arc of gold-bearing reefs extending from Evander in the east to Virginia in the west. Rarely exceeding two metres in thickness the gold reefs occur at depths of up to 5,000 metres. Gold was discovered near (what is now) Johannesburg in 1886 and, though early working was restricted to outcrop areas, the main structural features of the East Rand basin had been defined by 1910. Owing to the considerable depth of much of the known deposits it was not until 1930 that geophysical methods were used to search for continuations of these deposits. This search uncovered the westerly extension of the goldfields known as the ‘West Wits line’, and the Klerksdorp deposits further to the southwest. Since then the Orange Free State and Evander fields have also been developed.
