134 THE DESICCATIOX OF LATER GEOLOGICAL TIMES. 



dence of the correctness of this view is to be found in the occurrence of 

 sub-fossil Succinece, Helices, and Piipce in the clay deposits of Lake Pangkong, 

 while a land moUusk could, at the present time, hardly exist in that region 

 at all." 



That a large part of Siberia has been covered by water up to within quite 

 recent times seems well made out from the accounts given by various geo- 

 graphical explorers within recent years. To cite only one at the present 

 time, Cotta says, in his de.scription of the country between the Ural and the 

 Altai: ''The almost horizontal diluvial covering which, without interrup- 

 tion, spreads itself over so enormous an area, that, even when the roads are 

 in good condition, it requires nine days and nights of rapid travelling to get 

 across it, has evidently, at a very recent geological period, been covered by 

 water. We are taught by this fact that Europe, closed in by the Ural, was at 

 that time entirely separated from High Asia, whose northwestern coasts rose 

 precipitoasly [aufragten] in the Altai, the mountains of Turkestan, and the 

 Caucasus. This water, which formed a division between the two continental 

 masses, was evidently not a great lake, but a broad arm of the sea, which, 

 beginning at the Arctic Ocean with but moderate average depth, was con- 

 nected with the Mediterranean through the Black Sea, and perhaps even with 

 the Red Sea, across the Isthmus of Suez." * 



We have thus shown that High Asia and the countries adjacent to it on the 

 north and northwest have been, within the later geological epochs, the scene 

 of great physical changes, and that the diminution of the water-surface 

 through every portion of this vast area has attracted, in a marked degree, 

 the attention of recent scientific travellers. Without stopping, at the present 

 time, to discuss the statements presented, with reference to the real nature 

 of the phenomenon and its causes, it will be sufficient to call attention to the 

 fact, which cannot fail to have impressed itself on the mind of the reader, 

 that we have to do with an event — or, rather, a series of events — of the 

 utmost importance, if only for the immense size of the area involved in these 

 changes. The analogy between the phenomena presented in High Asia and 

 on its borders and those exhibited in the preceding section, with reference 

 to our own Cordillera region, is most marked, in so far as the existence of a 

 condition of desiccation, during present and past times, is concerned. 



Before entering, however, on the propo.sed general discussion of the sub- 

 ject before us, it will be desirable to present facts of a similar nature to those 



* Der Altai. Sein geologischer Bau, und seine Erzlagerstatteii. Lei]izig, 1S71. 



