190 GEOLOGY [Chap. IX 



Letter 526 



To J. D. Hooker. 



Down, Sept. 28th [1861]. 



It is, I believe, true that Glen Roy shelves (I remember 

 your Indian letter) were formed by glacial lakes. I persuaded 

 Mr. Jamieson, an excellent observer, to go and observe them; 

 and this is his result. There are some great difficulties to be 

 explained, but I presume this will ultimately be proved the 

 truth. . . . 



Letter 527 To C. Lyell. 



Down, Oct. 1st [1861]. 



Thank you for the most interesting correspondence. What 

 a wonderful case that of Bedford. 1 I thought the problem 

 sufficiently perplexing before, but now it beats anything I 

 ever heard of. Far from being able to give any hypothesis 

 for any part, I cannot get the facts into my mind. What a 

 capital observer and reasoncr Mr. Jamieson is. The only 

 way that I can reconcile my memory of Lochaber with the 

 state of the Welsh valleys is by imagining a great barrier, 

 formed by a terminal moraine, at the mouth of the Spean, 

 which the river had to cut slowly through, as it drained the 

 lowest lake after the Glacial period. This would, 1 can 

 suppose, account for the sloping terraces along the Spean. 

 I further presume that sharp transverse moraines would not 

 be formed under the waters of the lake, where the glacier 

 came out of L. Treig and abutted against the opposite side 

 of the valley. A nice mess I made of Glen Roy ! I have no 

 spare copy of my W^elsh paper 2 ; it would do you no good 

 to lend it. I suppose I thought that there must have been 

 floating ice on Moel Tryfan. I think it cannot be disputed 

 that the last event in N. Wales was land-glaciers. I could 

 not decide where the action of land-glaciers ceased and marine 

 glacial action commenced at the mouths of the valleys. 



What a wonderful case the Bedford case. Does not the 



1 No doubt this refers to the discovery of flint implements in the 

 Valley of the Ouse, near Bedford, in 1861 (see Lyell's Antiquity of Man, 

 pp. 163 etseg., 1863). 



2 " Notes on the Effects produced by the Ancient Glaciers of 

 Caernarvonshire, and on the Boulders transported by Floating Ice," 

 Edinb. New Phil.Journ., Vol. XXXIII., p. 352, 1842. 



