CHAP. VIII THE CAUSES OF GLACIAL EPOCHS 163 



This greater accumulation of ice in both hemispheres 

 would lower the whole ocean by the quantity of water 



believing that the high phase of excentricity which caused our own glacial 

 e[)Och was at all events an assisting cause. This is rendered more prob- 

 able if taken in connection with the following very definite statement of 

 glacial markings in South Africa. Captain Aylward in his Transvaal of 

 To-day (p. 171) says :— " It will be interesting to geologists and others to 

 learn that the entire country, from the summits of the Quathlamba to the 

 junction of the Yaal and Orange rivers, shows marks of having been swept 

 over, and that at no very distant period, by vast masses of ice from east to 

 west. The striations are plainly visible, scarring the older rocks, and 

 marking the hill-sides — getting lower and lower andless visible as, descend- 

 ing from the mountains, the kopjies (small hills) stand wider apart ; but 

 wherever the hills narrow towards each other, again showing how the vast 

 ice-fields Avere checked, thrown up, and raised against their eastern 

 extremities." 



This passage is evidently written by a person familiar with the phe- 

 nomena of glaciation, and as Captain Aylward's preface is dated from 

 Edinburgh, he has probably seen similar markings in Scotland. The 

 country described consists of the most extensive and lofty plateau in South 

 Africa, rising to a momitain knot with peaks more than 10,000 feet high, 

 thus ottering an appropriate area for the condensation of vapour and the 

 accumulation of snow. At present, however, the mountains do not reach 

 the snow-line, and there is no proof that they have been much higher in 

 recent times, since the coast of Natal is now said to be rising. It is evi- 

 dent that no slight elevation would now lead to the accumulation of snow 

 and ice in these mountains, situated as they are between 27° and o(f S. Lat. ; 

 since the Andes, which in 32° S. Lat. reach 23,300 feet high, and in 28° 

 S. Lat. 20,000, with far more extensive plateaus, produce no ice-fields. 

 We cannot, therefore, believe that a few thousand feet of additional eleva- 

 tion, even if it occurred so recently as indicated by the presence of stria- 

 tions, would have produced the remarkable amount of glaciation above 

 described ; while from the analogy of the northern hemisphere, Ave may 

 well believe that it was mainly due to the same high excentricity that led to 

 the glaciation of Western and "^Central Europe, and Eastern North America. 



These observations confirm those of Mr. G. W. Stow, who, in a paper 

 published in the Quarterly Journal of the Geological Society (Vol. xxvii. p. 

 539), describes similar phenomena in the same mountains, and also mounds 

 and ridges of unstratified clay packed with angular boulders ; while further 

 south the Stormberg mountains are said to be similarly glaciated, with im- 

 mense accumulations of morainic matter in all the valleys. We have here 

 most of the surface phenomena characteristic of a glaciated country, only 

 a few degrees south of the tropic ; and taken in connection with the indica- 

 tions of recent glaciation in New Zealand, and those discovered by Dr. R. 

 von Lendenfeld in the Australian Alps between 6,000 and 7,000 feet ele- 

 vation {Nature, Vol. xxxii. p. 69), Ave can hardly doubt the occurrence of 

 some general and AA'ide-spread cause of glaciation in the southern hemisphere 

 at a period so recent that the superficial phenomena are almost as well pre- 

 served as in Europe. Such evidences of recent glaciation in the southern 

 hemisphere are quite inexplicable without calling in the aid of the recent 

 phase of high excentricity ; and they may be fairly claimed as adding another 

 link to the long chain of argument in favour of the theory here advocated. 



M 2 



