Geological Aspects of South African Scenery. BYay5) 
The present surface, here as elsewhere, is the last expression of the 
interaction of various geological forces, some of which are as active 
to-day as they probably ever were, while others have in these days no 
share in the sculpturing of this landscape. Changes of temperature, 
wind and rain, surface and underground water, are probably not much 
less active in South Africa to-day than in past ages; whereas extreme 
glacial conditions have played no part in modifying the surface since 
the beginning of the Karroo Age, nor have voleanic agencies been at 
work since the eruption of the rocks of the Drakensbergen and the 
Lebombo Range. 
The record of the South African strata tells us that before the 
present conditions began there were five periods during which a land 
surface existed. The earliest of these, and yet not the first, was 
formed by the complex mass of old rocks, now largely metamorphic in 
character, which we group together as the Swaziland System. ‘To-day 
again these rocks play a large part in the constitution of the region, 
but whether any portion has remained continuously a land area 
eannot be determined. Certainly the northern granite and schist 
regions were dry land while the central and southern areas were 
eradually covered by the sea in which the Witwatersrand Beds were 
laid down. These beds in turn were added to the land surface, and 
in the process of upheaval they underwent considerable folding and 
contortion. Having been again submerged, portions of the eranite 
area, and probably the whole Witwatersrand System, formed the floor 
for the heterogeneous Ventersdorp System, with its succession of 
‘sediments and volcanic rocks, which in turn formed the third land 
surface that plays a part in the present one. When the next 
submergence ensued, the Black Reef, the Dolomite, and the Pretoria 
Series were deposited in the northern areas, which we know as the 
Transvaal, Bechuanaland, and Northern Cape Colony, though whether 
land conditions prevailed southward, or whether these beds were also 
deposited there, but were subsequently denuded, is again a matter of 
conjecture. At any rate, the evidence now available points to little 
deposition haying occurred in the south during that period. 
In the land surface next formed, the Swaziland, the Witwatersrand, 
the Ventersdorp, and the Potchefstroom or Transvaal Systems all 
played some part, there being a gradual increase in complexity from 
the north southward. 
During the next submergence there was deposited the Cape System, 
consisting of the Table Mountain, the Bokkeveld, and the Witteberg 
Series, so predominant throughout Western and Southern Cape 
Colony, but represented in Natal by the Table Mountain Series only, 
and in the Transvaal most probably by the Waterberg sandstones and 
conglomerates. 
When this period of deposition ended, the present terrestrial 
conditions began to prevail, for the characteristic Karroo System was 
not due to marine action, but, as is universally recognised, was formed 
mainly on the floor of an inland lake, while in the north land ice 
caused the extensive morainic deposit of the Ecca Glacial Con- 
glomerate. This inland lake must have covered the greater portion of 
the region, and its shores certainly extended considerably south of the 
DECADE Y.—VOL. IV.—NO. Vill. 23 
