WCP5478

[1]

Parkstone, Dorset.

Jan[uar]y. 9th. 1894

D. Pidgeon Esq.

My dear Sir

Thanks for your very interesting letter. Ever since I first took an interest in the subject of glaciers — more than thirty years ago — I have been looking for estimates of the quantity of mud in glacier streams. But, as you say, the quantity in the Greenland ice-cap streams would be far more valuable, as that would be all due to erosion. Yet even that might and give the full amount of erosion of the Old Alpine ice-sheets owing to the comparative deficiency of ¹[2] grinding material., due to the few mountain peaks above the ice. I wish you would write to "Nature" giving all that part of your letter referring to Greenland, and the vast importance of its mud-charged streams as an actual measure of the erosion due to an ice sheet. The Brit[ish]. Ass[ociatio]^n., Royal & Geog[raphical] Societies between them, should arrange to have these streams measured & tested for mud discharge in a year. It would not cost very much, & would give more valuable information than many more costly expeditions. [3]

The only recent paper on the American Great Lakes was that of Prof[essor]. J.W. Spencer² in Q.J.G.S.³of 1890; but he was against ice-erosion. It was injudicious of Ramsay⁴ to claim those lakes as ice-eroded, though it seems to me certain that ice-erosion must have deepened them in parts.

Shall return your letter for you to write to "Nature", or will you write afresh? What you say about Greenland will be a great contribution to the discussion.

Believe me | Yours very faithfully | Alfred R. Wallace — [signature]

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