Page:South African Geology - Schwarz - 1912.djvu/199

 Transvaal Silver Mine. Cobalt ores occur at Balmoral, on the Middleburg line.

The Waterberg System

This system consists of a single series divided into an upper sedimentary portion and a lower volcanic portion. The lower division consists of felsites with interstratified shales and is not present in the west of the area. The upper division begins with a basal conglomerate with fragments of banded and cherty rocks which are undoubtedly derived from the Pretoria Beds, and prove the unconformity between the Waterberg and Transvaal Systems. The sandstones and shales that follow are always stained red or a reddish buff; there is never any doubt about a Waterberg rock, owing to the peculiar tint. The formation is similar to the Torridonian of Scotland, but the localities are too far apart for lithological correlation to be of any value. In the extreme west the Waterberg is probably represented by the arkoses in Namaqualand resting on the granite. In the east the beds are continued in the Palæozoic sandstones of Natal, which should rightly end north of Durban. The sandstones south of Durban belong to the Table Mountain Series, but there is much confusion in regard to this point. In the north round Nyasa and Tanganyika the Waterberg is again met with as the "Old African Sandstones" and Mafingi System.

The reasons why the Waterberg Sandstone cannot be the same as the Table Mountain Sandstone, apart from their totally different texture and colour, are that as the Dwyka Conglomerate rests unconformably on the eroded surface of the highly compacted, partially