THE THREE PALEOZOIC ICE-AGES OF SOUTH AFRICA 



ERNEST H. L. SCHWARZ 



When Mr. Rogers and myself commenced the systematic geo- 

 logical survey of Cape Colony in 1896, we had no evidence before 

 us which would allow us definitely to refer to one period of glaciation 

 in the stratigraphical series. Sir Andrew Ramsay's discovery of 

 ice-action on pebbles in the Permian Conglomerates of Great Britain^ 

 had been discredited, and the failure of the Paleozoic glacial theory 

 in Europe had been taken to mean that it must be a failure in other 

 parts of the world as well; no matter how good the specimens of 

 glaciated bowlders and the photographs of ice- scored floors, or that 

 came home from India, Australia, or South Africa, no one would 

 believe in the Permian Ice Age. I was myself skeptical when I 

 first came to South Africa, and at a meeting in Cape Town, when 

 some of the glaciated Dwyka Conglomerate pebbles were exhibited, 

 assisted in recording the belief that there was in thesje scratches no 

 satisfactory evidence of ice-action. I have before me at the Albany 

 Museum some earlier bowlders collected by Mr. E. I. Dunn, together 

 with a slab from beneath the till which is scored by ice, and I do 

 not see how any definite opinion can be derived from them alone. 



In the field it is different ; there the evidence is overwhelming, as 

 I was soon to see when I joined the Geological Survey later on, but 

 the difficulty is to obtain specimens which in themselves show unmis- 

 takable signs of ice-action. When, therefore, I was in due time 

 convinced of the glacial origin of the Dwyka Conglomerate, I could 

 not merely record my opinion that the field evidence was satisfactory; 

 I had to produce specimens which would convince headquarters in 

 Cape Town. I sought for specimens of bowlders which were not only 

 characteristically scratched, but were also faceted. I obtained several 

 in the first year showing three or four definite friction- cut planes on 

 each, all bearing several series of parallel grooves, while the remainders 



I Quarterly Journal of the Geological Society, London, 1855, pp. 185-202; ibid., 

 1894, p. 463- 1 



683 



