Hall and Molengraaff have recently produced a memoir of outstanding importance dealing with the Vredefort Mountain Land on the border of the Transvaal and the Orange Free State (1925). Their account, which is a model of lucidity, is accompanied by a map and sections, and is copiously illustrated with photographs, mainly of rock slices. It includes a chapter on the History of Research, and another that introduces tectonic comparisons with the Black Hills of Dakota and Wyoming and the Ries Kessel near Nördlingen. The features of the Vredefort district that command most attention in this country are its tectonics and its flinty crush-rocks, or pseudotachylytes, to use Shand's alternative designation. Hall and Molengraaff's memoir supplies much new information on these two subjects, and also in regard to other topics, stratigraphical and petrographical, that are of rather more local interest. In the present notice, only one aspect of the memoir will be discussed, namely the tectonics of the Vredefort Dome.

An extensive collection of Eocene Foraminifera was made during a geological reconnaissance of parts of Western India undertaken on behalf of the Whitehall Petroleum Corporation by Mr. D. Dale Condit and myself. Further specimens have been lent by the Indian Geological Survey. As traced from north to south the region examined includes parts of the Dera Ghazi Khan District in the Punjab; the Loralai District, the Bugti Hills, the Bolan Pass, Kalat and Las Bela States in Baluchistan; the Laki Range and Indus valley in Lower Sind; and Cutch State. The distance from the northernmost area examined to the southernmost is approximately 550 miles. I have already published a brief account of the stratigraphical geology with palaeontological descriptions of the species of Foraminifera encountered (3 to 8). In this paper it is proposed to summarize the results of this investigation and compare briefly the zonal distribution and evolution of the species with that of the European Eocene.

As stated previously the aim of this paper is chiefly to call attention to the differences between the mineral assemblages of the Downtonian, Dittonian, and Farlow Sandstone beds of the Old Red Sandstone, particularly when the percentages of the different mineral grains are obtained by accurate counting. Further work will show how far these investigations may be correlated with the examination of the rocks in adjacent districts, and the author suggests that a similar calculation of percentage figures on the minerals of such deposits may assist in indicating more definitely the sources from which they have been derived.

It seems to be curiously difficult to obtain fair treatment for the theory of a continuously cooling earth and its consequence, the thermal contraction theory of mountain formation. After Davison and Darwin had calculated the available compression of the earth's crust on Kelvin's theory of the cooling of the earth, and obtained a result that was at any rate of an order of magnitude consistent with the observations then available, Osmond Fisher made a revised comparison, which amounted to supposing the mountains formed by compression all powdered and spread out uniformly over the whole surface of the earth; the thickness of the resulting layer was naturally very much less than the actual height of known mountains. So far as I have been able to trace, nobody protested against the assumption that the thickness of the material after it had been redistributed in this way was directly comparable with the height of the mountains as actually distributed, and Osmond Fisher's view seems to have been universally quoted as the last word on the subject. Even long after my rediscussion of the whole question in 1916, making allowances for the additional data provided by radioactivity, had again led to a result agreeing with observation within the uncertainty of the data, it was almost completely neglected in the literature of the subject, while Osmond Fisher's work retained undisputed pre-eminence.