Page:South African Geology - Schwarz - 1912.djvu/186

 Pal-Afric Group

The Swaziland (Namaqualand) Formation

This consists of gneisses and crystalline schists and unaltered sediments above, called the Moodies Series in the Transvaal, Kraaipan Series in Bechuanaland. The older name for the last was the Barberton Series; it consists of clay slates, quartzites with magnetic bands (calico rock), passing into phyllites and mica schists. Into this is intruded granite, which forms a continuous mass coming from Zululand, through Swaziland, and up along the Eastern Transvaal, through the Zoutpansberg to Rhodesia, and thence southwards through Bechuanaland to Namaqualand. Three bosses of granite occur south of Pretoria, which are important, as it is between them that the Witwatersrand Beds occur.

The most noteworthy areas in this system are: Swaziland, with the tin and monazite fields of Embabaan, and Barberton with the gold mines. Both lie between the precipitous escarpment of the Transvaal Drakensberg mountains and the Lebombo mountains on the east.

The Witwatersrand Formation

The Witwatersrand System is divided into a lower division, characterized by haematite slates separated by quartzite bands, and an upper, consisting mostly of quartzites with many bands of conglomerate containing gold.

The Lower Witwatersrand Beds commence with a very thick band of quartzites lying upon the granite, called the Orange Grove Quartzite, 1400 ft. thick. The escarpment of this quartzite faces north and forms the picturesque hill which runs north of Johannesburg.