Domes in Scotland and South Africa: Arran and Vredefort

Abstract

Hall and Molengraaff have recently produced a memoir of outstanding importance dealing with the Vredefort Mountain Land on the border of the Transvaal and the Orange Free State (1925). Their account, which is a model of lucidity, is accompanied by a map and sections, and is copiously illustrated with photographs, mainly of rock slices. It includes a chapter on the History of Research, and another that introduces tectonic comparisons with the Black Hills of Dakota and Wyoming and the Ries Kessel near Nördlingen. The features of the Vredefort district that command most attention in this country are its tectonics and its flinty crush-rocks, or pseudotachylytes, to use Shand's alternative designation. Hall and Molengraaff's memoir supplies much new information on these two subjects, and also in regard to other topics, stratigraphical and petrographical, that are of rather more local interest. In the present notice, only one aspect of the memoir will be discussed, namely the tectonics of the Vredefort Dome.