STOW SOTJTH-AFRICAN GEOLOGY. 545 



noticed, the closing up of these openings would turn large por- 

 tions of the present flats into wide lakes), there are no traces of 

 more recent lacustrine deposits that I know of ; so that, with the 

 exception of the unstratifled clays and boulder-clays, and a little allu- 

 vial soil, nothing is found, in this portion of the area, of later date than 

 the present drainage-system. This has, no doubt, tended in a great 

 measure to prevent a spontaneous renewal of timber-growth after the 

 extinction of the ancient forests (see p. 538), the soil having never 

 been renovated by new deposits formed beneath the ocean, as it has in 

 other countries. It must also be more difiicult for the seeds of trees 

 and plants to ascend to an elevated plateau than to spread over 

 plains on a lower level, or just emerging from the waters. 



Conclusion. — The foregoing collection of facts must, I think, tend 

 to prove that vast climatal changes have taken place during the de- 

 position of the various formations that have been brought under 

 review in this and the foregoing portions of my paper. It may be 

 objected that, with regard to such an extreme climate as is here 

 inferred. South Africa is too far removed from the present Antarctic 

 regions, and that the cavises of great changes of climate are not un- 

 derstood. 



The simple oscillation of the poles, however, taken together with 

 the continual and necessary alteration in the distribution of land 

 and water, would be surely sufficient to account for aU the pheno- 

 mena yet known, changing not only the geographical configuration 

 of the surface of the earth itself, but carrying with it the most im- 

 portant changes of climate over every portion of the earth. 



In such a case, when the London area possessed a tropical climate, 

 the spot now occupied by Algoa Bay would be at some 68° south 

 latitude ; or when the site of modern London was within or near 

 the Arctic circle, Algoa Bay would be within 5° or 6° of the equator, 

 with a temperature congenial to the existence of the large Veneri- 

 cardia of the Zwartkops Pliocene limestone (p, 534), In the former 

 case, South Africa would then possess (instead of mountains covered, 

 as at present, with snow for a few days in winter) an Antarctic cold, 

 with an ice-bound coast, and glaciers covering every portion of the 

 country. 



Lastly, I have to notice in connexion with the geology of South 

 Africa the rare occurrence of the remains of either fish or mammals. 

 "What has opposed their preservation? And further, was South 

 Africa the home of large Pachydermata during a period equivalent 

 to the Mammoth age? 



Until within a very few years, the rivers of South Africa swarmed 

 with Hippopotami ; and large herds of Elephants roamed over the 

 wide plains, which were also the home of the Giraife and the Rhino- 

 ceros, and where the large Carnivora, Leopard, Panther, and Lion, 

 preyed upon the weaker animals. Are we, then, to find, in our 

 Pliocene deposits. Ostriches of gigantic size, enormous Lions, and 

 Elephants eclipsing the Mammoth itself — analogues of the great 

 Marsuj)ials of Australia, the Mylodon, Megatherium, and Glyptodon 

 of South America, the Mastodon and Mammoth of the Northern 



VOL. XXVII. PART I. 2 p 



