112 E. T. Mellor — Glacial Conglomerate of South Africa. 



opportunities for study in the many sections exposed in the 

 deeply cut valleys of the eastern rivers. In this district the 

 Dwyka Conglomerate includes both unstratified and stratified 

 portions, in each of which facetted and striated bowlders are 

 abundant, together with many angular and sub-angular rock 

 fragments. The stratified beds are sometimes almost devoid 

 of bowlders and pebbles, and include mudstone and shales, 

 the latter indistinguishable from the overlying Ecca Shales into 

 which the Dwyka Conglomerate gradually passes. 



In 1899 Messrs. Rogers and Schwartz* studied the Glacial 

 Conglomerate in the Prieska district in the north of Cape Col- 

 ony. They found the Conglomerate here to present all the 

 features of a true ground moraine, with abundance of facetted 

 and striated bowlders ; and lying unconformable upon all the 

 older rocks of the district, fragments of which occur in the 

 conglomerate and which afford tine examples of " roches mon- 

 tonnees " and striated surfaces. The direction of the striae and 

 distribution of the bowlders point to a movement from the 

 north southwards. 



In his report for the same year Dr. Corstorphinef summed 

 up the results obtained in the north and south of Cape Colony 

 and elsewhere, and compared the features of the northern and 

 southern deposits, contrasting the northern Glacial Conglom- 

 erates, possessing the characters of a ground moraine, with the 

 southern Dwyka, which is to be looked upon as " a sediment 

 formed under a probably inland water, into which there floated 

 the icebergs calved from the front of the glacier or glaciers on 

 the northern shore." 



The identity in character of the Glacial Conglomerate with a 

 true ground moraine, seen in the northern parts of Cape Col- 

 ony, comes out with even greater clearness along the northern 

 edge of the main area occupied by the Karroo System in the 

 Transvaal. 



The Glacial Conglomerate in the Transvaal. — In the cen- 

 tral portions of the Transvaal, and particularly in a district 

 lying along the eastern railway line from Pretoria to Middel- 

 burg, I have recently mapped many outliers of Karroo rocks 

 isolated by the progress of denudation from the main body, 

 which covers extensive areas to the south and south-east. 

 These outliers sometimes include portions of the sandstones, 

 grits, and shales associated with coal-seams which form the 

 upper portion of the Karroo System as developed in this part 



*Eogers and Schwartz, Ann. Eep, of the Geol. Commission, 1899. Cape 

 Town, 1900. On the Orange Eiver Ground Moraine. Trans. Phil. Soc. S. A., 

 vol. xi, part 2, 1900. 



fG. S. Corstorphine, Ann. Eep. of the Geol. Commission, 1899. Cape 

 Town, 1900. (Full references to the previous literature will be found in this 

 paper.) 



