A Geological Survey of the Witwatersrand and other Districts in the Southern Transvaal

Abstract

I. I ntroduction . The importance of the Witwatersrand as a gold-producing area has given an impetus to geological enquiry in this part of South Africa. The result has been the appearance of numerous books, pamphlets, and papers. My apology for adding to their number by the present communication is a five-years' residence in the Transvaal, during which time I have had perhaps unusual opportunities and facilities for closely studying the geology of the Southern Transvaal, or more correctly the region lying between the Magaliesberg Range and the Vaal River. Having in the course of professional duties to journey backward and forward through this country, I gradually became acquainted with its geological structure; and as a means of crystallizing and correlating the information thus obtained, I began to lay it down on a map and have continued to do so until now. The survey of some 8000 square miles of country, embracing the districts of the Witwatersrand, Potchefstroom, and Heidelberg, and a portion of those of Rustenburg and Pretoria, being now completed, I desire to lay the results before the Geological Society. The difficulties of geological mapping in a sparsely-inhabited country, and where the inhabitants since the Jameson raid have not been particularly disposed to welcome the Uitlander, may be easily imagined. I do not claim for my map that accuracy in detail which can only be obtained by leisurely work on a large scale; still, the main geological boundaries have been drawn with as near an approximation to correctness as was