Reviews — Geology of the Transvaal, South Africa. 477 



At its base are found the Talchir Conglomerates, absolutely comparable 

 with the Dwyha Conglomerate. The older underlying rocks ( Vindhyau 

 limestones) have been found to be polished and striated in various 

 localities, e.g. near Chanda in the Central Provinces of India. The 

 Talchir shales are associated with this conglomerate ; they offer all 

 the characters of the Ecca strata, and like the latter they ai'e almost 

 everywhere devoid of fossils. On these glacial deposits rest sand- 

 stones comparable to the sandstone of the Upper Karroo, and in 

 which has been found a Glossopteris flora, very similar to that of 

 the Karroo. 



In Australia the traces of an ancient glaciation are not less 

 evident, and the glacial deposits which there also, as in the Salt 

 Range of India, are associated with sediments containing marine 

 fossils, show that the glaciation of these two continents was con- 

 temporaneous and took place during the last period of the Palasozoic 

 era. Moreover, the general affinities between the Karroo and the 

 Gondioana System are so evident that we must admit the con- 

 temporaneity of the Permian glacial deposits in South Africa, 

 India, and Australia. 



2. Upper Karroo. 



The strata of the Upper Karroo are almost everywhere found in 

 a normal and horizontal position ; they are composed of sand- 

 stones, argillites, arenaceous argillites, Carboniferous clays, and 

 Carboniferous strata. 



Horizon of the Coal. — In the Upper KaiToo of the Transvaal, 

 provisionally called by the author the Hoogeveld formation, are 

 found the Carboniferous strata which, on account of the continual 

 increase of the Witwatersrand mining industry, must prove a great 

 wealth to the country. The deposits are immense : the coal-mines 

 of the Transvaal will certainly supply the demands of the whole of 

 Africa for at least a hundred years. 



The Carboniferous strata of the Transvaal seem to be vegetable 

 alluvia, deposited by the action of torrents. Fragments of trunks 

 of Sigillaria, and trunks, branches, and leaves of several species of 

 Glossopteris, largely compose these coal-beds. 



The mode of formation of the Upper Karroo may be imagined 

 to have taken place in the following manner. After the retreat of 

 the glaciers the paysage morainique predominated in this region, 

 where the Dwyka Conglomerate was in a great measure covered, 

 and on all sides surrounded, by the Ecca strata. Erosion soon 

 began to exercise its destructive action, and the Lower Karroo 

 deposits were doubtless, in places, completely' remanies ; at the 

 same time a series of sediments, constituting the Upper Karroo, 

 were being deposited. These fresh-water deposits were accumulated 

 partly in the watercourses, partly in the lakes ; they were made up 

 of obliquely stratified sandstones and clays, and sometimes also of 

 strata of plant -remains, transported by the torrents; the latter 

 strata have become the present Carboniferous beds. Only a small 

 portion of the enormously developed Karroo System has been 



