Lakes. 433 



seems to be stratified boulder-drift, in which cases it 

 would appear that glaciers descended to the level of the 

 sea, and deposited their moraines there, and, breaking 

 up, floated about as icebergs bearing boulders. By-and- 

 by, the glacier that was produced by the drainage of 

 snow disappeared, and is now represented by water, 

 forming a lake dammed by a moraine, outside of which 

 lie long smooth slopes of stratified drift. In the ma- 

 jority of cases, however, as already stated, I believe that 

 most of these small lakes are only partly blocked in by 

 moraine matter, and that, like some of the large lakes 

 of both sides of the Alps which have moraines at their 

 outlets, even if these moraines were removed they 

 would be found to be entirely enclosed by solid rock 

 formations. 



Such lakes in Wales are always on a small scale, 

 but there are others on a larger scale, having a far 

 more important bearing upon the physical geography 

 of our country and of many other countries in the 

 northern hemisphere, and I have no doubt also in the 

 south. The theory which I propound is my own, and 

 in its first conception is not now much more than 

 seventeen years old. It gave rise at the time to a 

 considerable amount of opposition, and also to some 

 approval. 1 



There is no point in physical geography more difficult 



1 See The Old Glaciers of Switzerland and North Wales,' 1860, 

 Soon after the special paper was published in the ' Journal of the 

 Geological Society ' in 1862, it was with satisfaction that I received 

 a letter from Dr. Julius Haast, stating that the theory perfectly 

 applied to many of the lakes in New Zealand, and that he had 

 adopted it after the perusal of my paper. See also on the ' Erosion 

 of Valleys and Lakes,' 'Philosophical Magazine,' 1864, and 'Sir 

 Charles Lyell and the Glacial Theory of Lake Basins,' 'Phi- 

 losophical Magazine,' 1865. 



F F 



