230 Prof. Hughes, Criticism of the Geological [Oct. 30, 



The Cretaceous alone in the Coast Range of California near the 

 Bay of San Francisco are according to Whitney 20,000 feet thick 

 and 30,000 according to Diller in Shasta County. These are a 

 few examples of the extent of the earth movements ; and nearer 

 the margin of the Atlantic basin we have the same evidence. 



In the Appalachian chain, according to Claypole\ 96 miles 

 of sediment has been crowded into a breadth of 16 miles. When 

 we measure the enormous thickness of this sediment and re- 

 member that there must have been vertical extension to make 

 room for that amount of horizontal compression we realise the 

 vast magnitude of the earth movements implied by those figures. 

 To give an idea of the amount of depression we have only to 

 consider that in the Palaeozoic rocks of the Appalachians having 

 according to Hall a thickness of 40,000 feet, nearly every bed 

 gives evidence by its fossils of shallow water, and often by shore 

 marks of very shallow water^. 



When we have evidence of movements on such a scale within 

 each geological period and remember that the lowest depth of 

 ocean known is only 27,930 feet, we may well hesitate before we 

 accept any theories involving the permanence of oceanic areas 

 and may feel justified in calling in elevation and depression in 

 explanation of any phenomena which they would account for. 



The Indian Ocean Basin. 



The regions round the Indian Ocean basin show here and 

 there traces of glacial action in quite recent times. New Zealand 

 may have come within the influence of antarctic ice ; India is 

 close to some of the highest and coldest mountains in the world ; 

 but African glaciation calls for further explanation. 



Capt. Aylward® 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 Vaal 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 and less visible as, descending from 

 the mountains, the kopkies (small hills) stand wider apart ; but 

 wherever the hills narrow towards each other, again showing how 

 the vast ice fields were checked, thrown up and raised against 

 their eastern extremities." On this account Wallace^ remarks, 

 " The country described consists of the most extensive and lofty 

 plateau in South Africa, rising to a mountain knot with peaks 



^ American Naturalist, Vol. xix. p. 257. - Le Conte, p. 552. 



* Transvaal of to-day, p. 171. * Island Life, p. 157. 



