The Orange River Ground Morame. 119 
At Vilet’s Kuil near Beer Vlei, in the division of Hope Town, is a 
mass of amygdaloidal felsites and breccias rising above the general 
level of the neighbourhood as a range of low hills. The surrounding 
low ground is occupied by the glacial conglomerate, which is a part of 
the large conglomerate area of the south of Prieska and Hope Town. 
The surface of the felsite where it emerges from the conglomerate 
is hummocky, and the northern slopes of the hummocks are 
smoothed and striated, while the southern are much steeper and 
rough (Plate XV.). 
As in the case of the Jackal’s Water hills, the lower portions of 
the felsite where it emerges from the conglomerate alone retain their 
glaciated surface, and the striz become less distinct the further one 
goes from the conglomerate outcrop. It is unusual to find the striz 
preserved at a greater distance than 200 feet from the conglomerate. 
One cannot doubt, however, that the whole surface was once covered 
with them. 
At Vilet’s Kuil the striae run, on the average, about 10° east of 
south, and the lee side of the hummocks is on the south. 
It is important to note that the only rocks we have met with 
which show the scratches are the quartzite and the compact felsite. 
The conglomerate outcrop touches other rocks, such as the magnetic 
jasper series of Doorn Berg (Griqua Town series of Stow), granite, 
gneiss, melaphyre and crystalline limestone. So far as our observa- 
tions go none of these show striated surfaces, although on T’Kuip 
inliers of granite have the exact form of ‘‘ roches moutonnées.”’ The 
absence of striz is certainly due to the comparatively rapid weather- 
ing of these rocks. The Griqua Town series resist the weather well 
on the whole, but their outcrops are always jagged and sharp, owing 
to the unequal resistance offered by the thin alternating beds. The 
eranite, gneiss, and melaphyre have always a more or less deeply 
weathered crust, and the limestone has the peculiar rough surface 
produced by the solvent action of rain water. 
In 1889, Stapff* published a critical account of what had been 
written up to that time on the Dwyka conglomerate, and came to 
the conclusion that the evidence for a glacial origin was not 
sufficient. Amongst other things, he remarked that the scratched 
surfaces could be explained in other ways than by glacial agency. 
We have shown above that the positions of the striated surfaces 
observed in Prieska and Hope Town are just where they should be 
if they extend under the conglomerate, viz., on that part of the older 
rock most recently exposed by denudation. 
* “Das ‘glaziale’ Dwykakonglomerat Stidafrikas.” ‘‘ Naturwissenschaft- 
liche Wochenschrift,” 1889, Berlin, 
