﻿ME. E. T. MELLOE ON THE GLACIAL (dWYKA) [Nov. I905, 





Direction of Glacial Stride in portions op the Pretoria and 



MlDDELBURG DISTRICTS (TltANSVAAL). 





Farm. 



Locality 



! 



Direction 

 (true bearing). 



1. 



2. 

 3. 

 4. 

 5. 

 6. 

 7. 

 8. 

 9. 

 10. 



Eooikopjes, 209. 

 Eenzamheid, 121. 

 Spitzkop, 407. 

 Klipfontein, 346. 

 Schoongezicht, 316. 

 Eland sfontein, 245. 

 Vlakfontein, 570. 

 Witpoort, 408. 

 Bosseman's Kraal, 531. 

 Zorgvliet, 254. 



25 miles W. of Balmoral Station. S. 18° E. 



2m.N.W. „ „ S. 28° E. 



3mJ.W. „ „ S. 33° E. 



6^ m. N.N.W. „ „ S. 28° E. 

 18 m. N.W. „ „ S. 28° E. 

 12i m> N . m }> g. 330 E> 



15 m. N.N.W. „ „ S. 43° E. 

 9 m. S.W. „ „ S. 43° E. 



10| m. S.W. „ „ S. 43° E. 



16 m. S.W. „ „ S. 28° E. 



In nearly all cases, the glaciated surfaces afford clear evidence 

 that the direction of the ice-movement was from the 

 north southwards; and their evidence is further confirmed 

 by the composition and distribution of the boulders in the Glacial 

 Conglomerate, a very striking feature beiDg the predominance in 

 any locality of boulders formed of rocks occurring most abundantly 

 (or probably, in some cases, exclusively) to the northward of their 

 present position. 



The constancy of direction shown by the glacial striations over 

 wide areas, and the extensive development of the glacial deposits, 

 point to the conclusion that in early Karroo times an ice-sheet of 

 considerable magnitude existed as far north, at least, as the present 

 position of the Northern Transvaal. 



In the Prieska district of Cape Colony, Messrs. A. W. Eogers 

 & E. H. L. Schwarz found the general trend of ice-movement to 

 have been from north-north-east to south-south-west. 1 The same 

 direction is given by Dr. A. Schenck from a locality near the 

 junction of the Orange and Vaal Rivers 2 ; in the Yryheid district 

 Dr. G. A. F. Molengraaff gives the direction of movement as from 

 north-west to south-east 3 ; and in the examples cited above the 

 general direction is from north-north-west to south-south-east. 

 The direction of movement of the early Karroo ice-sheet in South 

 Africa appears, therefore, to have been generally in a southerly 

 direction, and its origin must be looked for to the north. 



The Northward Extension of the Glacial Conglomerate. 



During the field-work of 1904, outliers of the Karroo System, 

 including the Glacial Conglomerate, were found considerably farther 



1 ' The Orange-River Ground-Moraine ' Trans. S. A. Phil. Soc. vol. xi (1900) 

 p. 117, 



2 'Ueber Glacialerscheinungen in Siid-Afrika' Verhandl. des Vlllten 

 Deutsch. Geographentages in Berlin, 1889, p. 153. 



'Geology of the Transvaal ' Johannesburg, 1904, p. 69, note. 



