Page:South African Geology - Schwarz - 1912.djvu/208

 and in addition conglomerates formed by the movement of rocks along faults, whereby the original fragments of the crush breccia are rounded, are also found; hence three types of conglomerate occur, each very similar in appearance and each carrying gold, but all three are of very different origin.

The Karroo Formation in Rhodesia consists of sandstones with some shales and rare bands of limestone, besides seams of coal which are thick and of good quality. It extends all through the north of Matabeleland, and southwards near the Limpopo from Tuli to the Sabi River. The only mine at present worked is at Wankies. The fossils of the series are freshwater forms, and include the fish Acrolepis, the little freshwater bivalve Palæomutela, Calamites (Schizoneura?), and Glossopteris.

The Forest Sandstone is a loose white sandstone with peculiar concretions of agate. It is an excellent building stone. The Batoka basalts, which follow, occur most prominently at the Victoria Falls; they stretch southwards into the Kalahari Desert, and westwards beyond the great bend of the Zambesi above the Linyanti Falls. On the east they are cut off by the great Deka Fault, which brings up against them the Matobola Beds with the Wankies coal seam.