A REVIEW OF THE EVIDENCE FOR MARINE CONDITIONS IN SOUTHERN AFRICA DURING DWYKA TIMES
McLachlan, I. R.
BERNARD PRICE INSTITUTE FOR PALAEONTOLOGICAL RESEARCH
The faunas of the three major Dwyka basins in southern Africa are listed in the form of tables. Marine invertebrates have been recorded from the western part of the Kalahari basin and from the Warmbad basin, but had not previously been confirmed within the Great Karroo basin. A new fauna from the base of the Upper Dwyka shales near Kimberley is described. Cephalopods, brachiopods and lamellibranchs are found in calcareous concretions, which also contain palaeoniscoid fish, coprolites, fossil wood and the mineral glauberite. The marine invasion into South West Africa postulated by Martin & Wilczewski (1970) therefore extended into the Great Karroo basin as well. By the time of accumulation of the White Band at the top of the Upper Dwyka shales, conditions were probably non-marine; with the possible exception of the Notocarid crustaceans, the White Band fossils are not, in themselves, indicative of marine conditions. The only other significant indication of marine conditions in the Great Karroo basin is the glauconite in the deltaic Coal Measures of the Ecca in the northern part of the basin. It is possible then that the fossiliferous marine shales near Kimberley accumulated as a fine-grained offshore facies of the Ecca deltaic sequence.