NOTES ON THE GEOLOGICAL FORMATION OF 

 PORTIONS OF GERMAN SOUTH-WEST AFRICA. 



By W. Versfeld, B.A., B.Sc. 



The localities examined are the following- : — 



(i). A strip of country about 20 miles from the coast, stretching 



from Velloors Drift and Ramans Drift on the Orange River 



to Keetmanshoop, via Warmbad and the Karas Mountains 



— a total length of nearly 200 miles. 



(2). The coast belt from Luderitzbucht to Pomona, on which are 



situated some of the best known Diamond Fields, 

 (i). The first-named locality may be divided into two very 

 distinct sections, namely (a) From the Orange River to the Karas 

 Mountains to Keetmanshoop. Here the prevailing rocks are 

 g-ranite and gneiss, overlaid in the northern parts by Table Moun- 

 tain sandstone and Dwyka conglomerate, (b) From the Karas 

 Mountains to Keetmanshoop. Here the prevailing rocks are 

 Malmsbury Schists, overlaid to a great extent in the southern pait 

 by Table Mountain sandstone and having- enormous intrusions of 

 dolerite in the northern part. 



The Great Karas Mountains form the zone of contact of the 

 Granite and the Malmesbury Schists. 



It will be observed that I have adopted the names of the corre- 

 sponding- series in the Cape Province. The beds corresponding to 

 the Cape series I have called Table Mountain Sandstone and to the 

 Archaean Schists, Malmesbury Schists, though for the latter I 

 would suggest a local name of "Karas Series" on account of their 

 enormous development in the Great Karas Mountains. 



A glance at the accompanying plan and sections will shew the 

 distribution in greater detail. The geological sections do not 

 represent a straight line but shew the formations passed over in 

 travelling- over the following route : Velloors Drift (on the Orange 

 River), Velloor, Warmbad, Dreihoek, Kanghus, Waterfall (South 

 West portion of the Great Karas Mountains), Quickachis, Harige 

 Kaakebeen and Keetmanshoop. An additional section is shown 

 from Dreihoek to Quickachis via Groendoorn (at the South East of 

 the Little Karas Mountains). 



Most of the above-named places have other native names, which 

 arc generally unpronounceable by Europeans. 



The country between Orange River and Dreihoek — a distance of 

 about 80 miles — may be described as an enormous mass of Granite 

 and Gneiss, shewing here and there traces of the original Schists 

 into which the Granite was intruded and only in the neighbour- 

 hood of Dreihoek being overlaid by younger sedimentary rocks, 

 namely Dwyka Conglomerate. At several spots intrusions of basic 

 volcanic rocks are observed. 



The Granite and Gneiss vary enormously in their nature and 

 ap-.earance. One often merges gradually into the other, but m 

 many places there is evidence that eruptions have taken place at 



