384 Report S.A.A. Advancement of Science. 



GEOLOGY. 



The systematic study and observation of the facts recorded in the 

 rocks, which throw light on the general structure of the more 

 southerly part of the African Continent, have been carried on by the 

 Geological Commission during the' past seven years, and the collec- 

 lioni and interpretation of the phenomena met with have done much 

 in deciphering the historx of the formation of the earths crust ii? 

 these regions, and have gone far to unravel the mysteries of the far 

 distant past. 



The \ast abvss of time which these archives embrace is ha[)pily 

 divided in two by the records of a change of climate, singular for 

 this latii''de. and unsuspected in .so remote an era; and this can be 

 conveniently used to separate the groups of sedimentary strata into 

 the older and the }ounger rocks, especially as the much tilted posi- 

 tion of the former contrasts with the nearlv horizontal beds of the 

 latter. 



There is no beginning to this history, only, far back in the early 

 stages of continental evolution in this hemisphere, a group of rocks 

 of aqueous origin was formed, but where the sediments came from, 

 or how these sea deposits Avere made, is a subject difficult even to 

 speculate on. Nothing can be seen but the remnant of an ancient 

 land, a relict of the remote past. ])laned down to a sea level bv the 

 denuding forces of countless ages, crumpled by stupendous crustal 

 movements, and through it have intruded the once molten masses 

 from below, which, sunk again deep below the ocean, for millions of 

 years perhaps, have made a foundation (in which to build another 

 Continent — one we know more of. 



A part of this Continent, which prol)abI\ extended far to the 

 South, and possibly was connected with India and Australia, is the 

 land of to-day in the Southern portion of this Colony. It has been 

 formed, layer by layer, in ancient seas, of the water-borne debris of 

 Continents no longer known in connection with the present distribu- 

 tion of sea and land. Again, it has risen above the surface in 

 obedience to the mysterious laws of elevation and subsidence, to 

 which land appears subject, and the very alphabet of which is as yet 

 dimly understood. Standing thus, exposed to denudation, active 

 through a hundred thousand centuries, its upper beds have, in places, 

 been cleared away, and even the lowest strata laid bare. In the Cape 

 Peninsula the first layer of Table Mountain sandstone can be seen 

 resting on the tilted strata of the ancient Malmesbury slate formation, 

 and on the denuded surface of the granite rocks ; but inland towards 

 the North and East, as the land rises, the two succeeding grej. t groups 

 of strata are still found at the surface of the ground — the earlier, 

 known as Bokkeveld Beds, occupying the Southern Karroo, and the 

 later forming the mountains beyond, called Witteberg Beds. These 

 older formations are chiefly composed of schists, .slates, quartzites. 

 sandstones, and shales, and. after having been folded into mountain 

 ranges, have suffered much denudation, and this espec'allv nearer the 

 coast. 



