Page:South African Geology - Schwarz - 1912.djvu/142

 are, therefore, three separate areas, and the order of the description will be from the south to the north, as in that way we shall avoid a great deal of repetition, for many occurrences in Rhodesia, for instance, cannot be understood without reference to what is found in the Transvaal, and what is found in the Transvaal can only be explained by comparison with the geology of Cape Colony. The individual formations will be described from below upwards that is to say, the oldest formations first, and then through successive formations to the most recent.

CAPE COLONY

Pal-Afric Group

Malmesbury Formation

This formation consists of ancient slates and occasional limestones, quartzites, and conglomerates, which occur in the south of Cape Colony. It is a comprehensive term which undoubtedly includes many divisions of rocks of greatly differing age, but which the badness of the exposures does not allow us to properly distinguish. The beds are for the most part highly inclined, and have been crushed into folds, which has obliterated divisions and occasionally produced such metamorphism that the rocks appear to belong to an altogether different system, which perhaps they do.

The typical area is not Malmesbury, where the rocks are metamorphosed to crumpled mica schists, but at Cape Town. Here one finds on the north of the granite a great series of massively bedded slates, clay slates, and slaty sandstones dipping north at a considerable angle, from 45 to 85. The rocks are blue-black to grey in