The topography of Johannesburg is distinctive with the rocky mountainous ridges and the line of koppies that runs from east to west. These are the quartzite ridges of the famous Witwatersrand. The geology is unique. Viljoen and Reimold (An Introduction to South Africa’s Geology and Mining Heritage) make the point that this is one of the few localities where the evolution of the granitic crust of Southern Africa has been preserved and can be viewed. There are several places in Johannesburg where approximately 500 million years of the Earth’s history is exposed and displayed. One needs a geological guide, but what one sees is a layering of hard quartzite rock and sediments of shale above the quartzite, within the Witwatersrand super group. To the south is the further layering of conglomerates with the gold bearing reefs, such as the Main Reef, Main Reef Leader, South Reef, Promise Reef, Kimberley Reefs etc.
Some of the best spots to see geological time exposed are on either side of the rock lined quartzite roads of the cuttings and passes of Johannesburg. Here we are looking at more recent history. It is some 130 years since gold was discovered and the city of Johannesburg was founded. People settled on the ridges and hills as well as in the valleys and dales. The residential properties located on the ridges are considered to be the most desirable for their views, their elevations and their well-established trees and gardens. The air seems fresher, cleaner, clearer...
