WCP6887

[1]

Parkstone, Dorset.

March 30th 1891

Dear Mr Fisher

I was glad to have your letter and to find that you are a believer in the glacial-lake theory. The subject has always had a fascination for me, and ever since I saw the glacial marks in N. Wales around Snowden and read Ramsay's papers, I have been a firm convert

Now, the wonderful proofs of the enormous extent & thickness of the ice-sheet in N. America and overq the British Isles, and of its marching over hill and valley and carrying portions of the sea-bottom far inland & up to 1200 high on Snowden, renders it far easier to understand how it could grind out lake-basins. I am just reading Wrights "Man in the Glacial Epoch", which [2] give us an excellent summary of the glacial phenomena in America and Europe. The chapter on British Glaciation is by Prof. Percy F. Kendall of the Yorkshire College, Leeds, and he gives the evidence for the Moel Tryfaen beds being seabottom carried up by the ice sheet, and it seems to me conclusive, and does away with the mythical 1500 feet subsidence. Nothing is said about lakes, however except to show the enormous extent and thickness of the glacial deposits in N. America, which have blocked up and buried the old drainage lines, and so obscured the natural surface that it is impossible to tell what old river beds may have drained the valleys now occupied by the Great Lakes. Do you know of any good geological account for our Lakes [3] of the Lake District, showing how far they are true rock basins, then depth &c.[?] Looking at the Map, it seems impossible to explain them by earth-movements, as it would require so many distinct local movements. I do not know if it is in consequence of my letter, but Bonney has just read a paper at the Geog. Society against the glacial origin of lakes. I am glad of this, as I shall hear what can be said against it. I did not think much of the article or paper he wrote some years back. Your suggestion as to the water helping to float the thin end of the glacier is good, and does away with all difficulty as to the motion up-hill. I had all the papers by Ramsey & others on the subject, but before moving here got rid of them. I wrote the letter partly to excite discussion preparatory to writing [4] an article on the subject in the Fortnightly. Did you see my article on "Inaccessible Valleys" in the "Nineteenth Century" of this month? If you have any paper or book giving facts as to which lakes are rock basins and which not, I should be obliged for the loan of them, but I am in no hurry.

I have been reading Mellard Reades "Origin of Mountain Ranges" and have been greatly impressed and pleased with it. Prof. Green pooh-poohed it in "Nature" but it seems to me a remarkable book, serving to complete your work. I do not think you referred to it. It does certainly explain the upheaval and crumpling for the masses of strata which form mountains, — but there still remains the great upheavals without crumpling or much disturbance, which seems an even more difficult problem. Have any of the Alpine geologists written recently on the lake-basins?

Yours very truly | Alfred R. Wallace [signature]