Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/712

 covered for many miles with clay, and innumerable angular fragments of rock are thickly strewn over the surface. At Beaufort this unstratified clay is from 30 to 40 feet thick. In Lower Albany, again, similar angular pieces of rock are spread over a large extent of country ; some of the latter fragments I have found with one or more polished surfaces. Some of the Dutch farmers offered to explain the circumstance by stating that the polish was occasioned by the wild bucks rubbing against them ; but as they were often in such positions that the bucks could not get at them, such an explanation cannot be received.

Glacial agency. — Future investigations may modify some of the conclusions I have arrived at ; but here are a number of phenomena that cannot be well explained by the theory of ordinary atmospheric and aqueous agencies, — the rounding-off of the hills in the interior of tbese ancient basins ; the numerous dome-shaped rocks ; the enormous erratic boulders, in positions where water could not have carried them ; the frequency of unstratified clays ; clays with imbedded angular boulders ; drift and lofty mounds of boulders ; large tracts of country thickly spread over with unstratified clays and superimposed fragments of rock ; the Oliphant's Hoek clay and the vast piles of Enon Conglomerate — all these seem to indicate periods when the climate was far more severe than at present : these are phenomena, in fact, which in other countries are considered to indicate accumulations and deposits requiring the wearing action of ice and extreme cold to account for their production.

Succession of Periods &c. — Having thus tried to point out the probable causes of the vast denudation of the Dicynodon strata, I cannot help believing that it did not all take place at the same period; the Enon Conglomerate and the enormous gaps that I noticed as occurring between some of the different coast-formations seem to point to this. Another evidence of the same kind appears to be the remarkable " whirled " rock that I have alluded to (p. 539), found on the north side of the Bongolo Neck. This rock was evidently at one time the outlet of the present Quoquodala basin, before the deeper opening towards Glen Grey was formed. In this place we not only find unstratified clay with boulders, but this again is placed upon what I have called a " whirled " sandstone, because it looks as if, while it were yet soft, it had been stirred up, and rolled together by ice enveloping the boulders imbedded in it (Section AD). These last are mostly angular, and occur in every position, not having been deposited according to size, as would have been the case had water been the agent. This sandstone is evidently far more ancient than the superincumbent clay, which appears almost recent in comparison.

There seems little doubt that the whole of the Dicynodon formation, since the close of the period when its last strata were deposited, has been high above the level of the sea, and its elevated position has prevented any great accumulation of soil taking place ; for since the great denudation, and since the present transverse river courses have been cut through the mountains (although, as I have before