130 FORMER LAND CONNECTIONS. 



only in the Cape, but in the Transvaal and Southern Rhodesia as 

 well — are most closely allied to forms in Germany, where compar- 

 able climatic conditions prevailed, while the influence of South 

 Africa seems to be recorded in the strange desert fauna of the 

 equivalent Elgin Sandstone of Scotland. Certain European genera, 

 reached Brazil, India, and Australia as well as South Africa. 



Desert Conditions during the Triassic. 



The climate in South Africa with one marked pluvial interrup- 

 tion had for long been on the border-line of semi-aridity, as indi- 

 cated by curious maroon and green shales and mudstones, calcareous 

 nodules and peculiar sandstones, so that it is not surprising to 

 find arid conditions having set in over a very large region at the 

 extreme close of the Triassic. 



This desiccation was most acute in Rhodesia, a territory which, 

 like all desert regions of the present day, is situated within the 

 sub-tropical belt; even in parts of Europe at this period similar 

 conditions held sway. An even mantle of very fine wind-worn 

 sand became spread over the face of the land, while in the region 

 more to the south the level of the ground was gradually raised by 

 fine dust blown thither by the prevailing north-westerly wind. This 

 deposit, in places hundreds of feet in thickness, is in certain litho- 

 logical characters rather like the loess of China, and is white, 

 cream, or pink in colour, known in Rhodesia as the Forest Sand- 

 stone, in the Transvaal as the Bushveld Sandstone, and in the 

 Cape and Natal as the Cave Sandstone. Its scanty fauna include* 

 forms with long slender limbs, a peculiarity of animals inhabiting 

 steppes, while signs of vegetation are wanting. 



Conditions such as these existed simultaneously in Southern 

 Brazil and probably in North-Eastern Rhodesia and the Congo 

 Basin, while there are indications to that effect in India as well, 

 but not in Eastern Australia; of those of Western Australia there 

 is no evidence as yet. 



VOLCANICITY AT THE CLOSE OF THE TRIASSIC AND ITS RESULTS. 



Such were the environmental conditions when simultaneously 

 South Africa, Central South America, and India were overtaken 

 by violent volcanic eruptions, at first through pipes and later from 

 fissures, while the process of deposition was stopped by the pouring 

 out of vast quantities of basaltic lavas. Some of the molten 

 matter, unable to reach the surface, burst in various directions 

 through the basement strata and solidified, forming innumerable 

 sheets of dolerite. At the same time great movements of the 

 earth's crust were initiated and the breaking up of Gondwanaland 

 began. 



In South Africa the lavas not only formed a huge pile thou- 

 sands of feet in thickness over the Basutoland region, but over- 

 whelmed extensive tracts in the Central and Northern Transvaal, 

 Southern Rhodesia, the Zambezi Valley, Nyasaland, and two areas 

 in S.W. Africa. In Brazil, Uruguay, and Paraguay the basalts 



