E. T. Mellor — Glacial Conglomerate of South Africa. 115 



which they are liable to be confused, but differing in the more 

 orderly arrangement of their materials, including a definite 

 orientation of the pebbles and bowlders. These secondary 

 conglomerates occasionally occur at the base of the purely 

 sedimentary series which succeed the true glacial deposits, and 

 by which as a result of a period of long continued subsidence 

 the latter were ultimately entirely covered. This sedimentary 

 series included the succession of beds constituting in the Trans- 

 vaal area the upper portion of the Karroo System. Later 

 formations were also possibly represented but of these no ves- 



tige has hitherto been discovered in the Transvaal. Raised 

 subsequently to an average elevation of 5000 feet above the 

 sea, the Karroo System has been again subjected to denuding 

 forces and the removal of the overlying sandstones, shales,[and 

 grits of the Coal Measures has laid bare extensive areas of the 

 underlying Glacial Conglomerate. 



Although modified by the double process of denudationHo 

 which it has been subjected, it still presents in its distribution a 

 striking similarity to that of more recently formed glacial 

 deposits. Following the contours of the land surfaces upon 

 which it was originally laid down, it ranges within distances of 

 a few miles through variations in elevation of three to five 

 hundred feet. It is frequently well developed on one slope of 

 a hill and entirely absent from the other. When protected 



