[87b] Ibidem, p. 139.
[88a] Ibidem, p. 123.
[88b] This subject has been fully gone into by Mr. P. F. Kendall, F.G.S., in his article “The Cause of an Ice-age,” contributed to the “Transactions of the Leeds Geological Association,” part viii. Other ice-streams also passed down various alleys from Teesdale to Airedale, and the Ouse.
[88c] See an article “On the Occurrence of Shap Granite Boulders in Lincolnshire,” by Mr. W. T. Sheppard, in the “Naturalist” of 1896, pp. 333–339. Also the “Presidential Address to the Yorkshire Naturalists’ Union,” by J. Cordeaux, F.R.G.S., M.B.O.U., in the “Naturalist” for 1897, pp. 195, 6. See also a very interesting article in the “Fortnightly Review,” November, 1863, on “The Ice-age and its Work,” by A. R. Wallace, F.R.S.
[89a] Mr. J. Cordeaux gives this thickness in the “Naturalist” (1897, p. 186). Professor J. Geikie says it “did not exceed 3,500ft. or 4,000ft. at most, and would take 3,000ft. as an average.” (“The Glacial Period and Earth Movement,” a paper read before the Victoria Institute in 1893. Trans. No. 104, pp. 221–249, where also the question is largely considered of the causes of the Ice-age).
[89b] Mr. Wallace says; “Every mountain group, north of the Bristol channel, was a centre from which, in the Ice-age, glaciers radiated; these became confluent, extensive ice-sheets, which overflowed into the Atlantic on the west, and spread far over the English lowlands on the east and south.” “The Ice-age and its work.”—“Fortnightly Review,” Nov., 1893, p., 269.
[90] Quoted by Mr. Wallace in “The Fortnightly,” p. 630.
[91a] Quoted from “Glacialist’s Magazine,” “Fortnightly Review,” Nov., 1893, p. 631.
[91b] A list of Scandinavian boulders, which have been found in Lincolnshire is given by Mr. T. Sheppard, in the “Glacialists’ Magazine,” vol. iii, 1895, p. 129. Notices of lakeland boulders are given in the “Naturalist” of 1897, pp. 67, 103–104, 195–6, 283–4; and of 1898, pp. 17–20,85–87, 133–138, 221–224. In the Quarterly Journal of the Geological Society for May, 1885, Mr. Jukes Brown gives the general range of the boulder clay in Lincolnshire, while its range of flanking rocks in our own more immediate neighbourhood is treated of in the Government Geological Survey of “Lincoln and the Country around,” pp. 2, 122–129, 155, 156.
[91c] The average rate of a glacier has been computed at 64 inches for the four summer months; in other cases one inch a day. The progress, of course, varies with the slope or smoothness of its bed, and is more rapid in the centre than at the sides, where it scrapes against flanking rocks.