258 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 21, 



races, or stratified beds of earthy matter, are inconclusive. And I 

 think Dr. Hooker, in his valuable ' Himalayan Journal/ has rightly 

 explained, by glacier- action, many such phenomena in the Sikkim 

 valleys. From the disposition of the rivers and the mountains in 

 Northern India and Thibet, it seems to me that there may have 

 arisen some glacier-lakes in those countries on a very large scale. 

 The great alluvial plain of the Upper Sutlej, for example, which 

 Col. Strachey has described and referred to marine action, may 

 have been accumulated in a great lake dammed up by glaciers and 

 moraine -matter from the high mountains below Bekhar*. The 

 upper reach of the Bramahpootra and many other valleys may have 

 been blocked up in a similar way. 



More important effects, however, than these must have flowed 

 from the refrigeration of the climate of Central Asia during the 

 glacial period, and which I have not seen noticed. The great basin 

 of the continental streams, larger than the area of Europe, is re- 

 markable for its inland lakes from whence no streams ever reach 

 the ocean, owing to the great heat drying up the water. Now this 

 heat and dryness being much lessened during the glacial period, 

 there must have resulted a much smaller evaporation, which would 

 no longer balance the inflow. These lakes therefore would swell 

 and rise in level, and thus the Caspian, the Aral, and the Balkash 

 might have spread until they became more or less connected into a 

 wide inland sea, discharging its overplus into the Euxine, or along 

 that depression skirting the east flank of the Ural noticed by Hum- 

 boldt. This rise of the Caspian, damming back the waters of the 

 Volga and other streams, would occasion large deposits of alluvial 

 matter over the surrounding flat regions, and account for many of 

 the freshwater beds that occur there. The other great Asiatic de- 

 pression to the north of the Kuenlun Mountains would likewise be 

 filled up with water, and it is somewhat curious to find that the 

 Chinese have a tradition that Lake Lhop once drained into the 

 Hoang Ho. 



The sandy deserts of Central Asia are probably the dried-up beds 

 of these inland seas. 



§ 7. Intensity of Glacial Action on the West side of Scotland. 



So far as I have observed, the traces of glacier-action are much 

 more striking in the "West Highlands than in the east of Scotland. It 

 has occurred to me that as the amount of rain along the west coast 

 far exceeds that on the east, so in former times the precipitation of 

 snow may have been in like excess. Hence larger glaciers would 

 be the result. The volume of the streams in Lochaber in relation 



* Quart. Journ. Greol. Soc. vol. vii. pp. 306-308. Since writing the above, I 

 have read Dr. Thomson's description of this locality in his ' Travels in W. Hima- 

 laya and Tibet,' and his account confirms me in the opinion above expressed. 

 The ice of the Piti and Parang valleys has been probably instrumental in dam- 

 ming the Sutlej near Lio. The lacustrine clays of the Upper Indus may like- 

 wise be explained by supposing that valley to have been blocked up below Rondu 

 by the ice of the Gilgit valley, whose glacier seems still to descend lower than 

 any other in the W. Himalaya. (See Thomson's Travels, 1852, p. 482.) 



