Page:South African Geology - Schwarz - 1912.djvu/192

 The Vaal (Ventersdorp) Formation

This is a most unsatisfactory system, consisting of sediments and lavas mixed up in a way that it is impossible to describe them adequately in a short résumé. The

original name was Pniel Rocks, given by Stow in 1873, which was used for the amygdaloidal melaphyres found along the Orange River in the vicinity of the diamond diggings. This character is maintained in several occurrences in Prieska and also on the Rand, where the Klipriversberg Amygdaloid forms a range of hills to the south. In Kimberley, where the rock shafts of the mines penetrated the melaphyre at about 700 ft., a quartzite was encountered which was followed down to 1528 ft., then