Lakes. 439 



stance that all the large lakes lie in the direct channels 

 of the great old glaciers each lake in a true rock-basin. 

 This is important, for though it is clear that the drain- 

 age of the mountains must have found its way inta 

 these hollows, either in the form of water or of glacier- 

 ice, yet if ice had nothing to do with their formation, 

 we might expect an equal number of lakes great and 

 small in other regions where the rocks are equally dis- 

 turbed or of like nature, but where there are no traces 

 of glaciers. I have never observed that this is the 

 case, but rather the reverse. 



I will take the Lake of Geneva as a special example 

 (as I did in my original paper) before applying the 

 theory to our own country. This lake, once more than 50, 

 is now about 40 miles, long, its upper end between the 

 neighbourhood of Bex and the mouth of the Khone having 

 been filled with moraine matter and alluvium. In its 

 broadest part about 12 miles wide, it lies at the mouth 

 of the upper valley of the Ehone and directly in the course 

 of the great old glacier, which was more than a hundred 

 miles in length from the present glacier of the Rhone 

 to where at its end it abutted upon the Jura, by about 

 1 30 miles in width at Geneva, from south-west to north- 

 east, at what was once considered to be its lower end. 

 There, however, it is now known that its bulk was 

 swelled by the tributary glaciers of the Arve descending 

 from Mont Blanc, and of the valleys of the lakes of 

 Annecy and De Bourget, flowing west and north-west 

 from the high Alps further south, so that its most 

 westerly edge lay at least 60 miles beyond Geneva, as 

 far as Lyons on the Rhone. 



In old maps, showing the extent of the great ancient 

 glacieis of Switzerland, authors were somewhat too 

 timid, and large blank spaces were here and there left 



