Warren TTpham — Pleistocene Climatic Changes. 345 



known to have had local glaciers. Not until we go back to the 

 Permian period, closing the Palseozoic era, are numerous and widely- 

 distributed proofs of very ancient glaciation encountered. Boulder- 

 bearing deposits, sometimes closely resembling Till and including 

 striated stones, while the underlying rock also occasionally bears 

 glacial grooves and strise, are found in the Carboniferous or more 

 frequently the Permian series in Britain, France, and Germany, Natal, 

 India, and South-Eastern Australia. In Natal the striated glacier 

 floor is in latitude 30° south, and in India only 20° north, of the Equator. 

 During all the earth's history previous to the Ice-age, which con- 

 stitutes its latest completed chapter, no other such distinct evidences 

 of general or interrupted and alternating glaciation have been found ; 

 and just then, in close relationship with extensive and repeated 

 oscillations of the land, and with widely distant glacial deposits 

 and striation, we find a most remarkable epoch of mountain-building, 

 surpassing any other time between the close of the Archaean era and 

 the Quaternary. Mr. Alfred Russel Wallace therefore concludes that 

 eccentricity of the earth's orbit, though tending to produce a Glacial 

 period, is insufficient without the concurrence of high uplifts of the 

 areas glaciated. He thinks that the last time of increased eccen- 

 tricity, 24.0,000 to 80,000 years ago, was coincident with great 

 altitude of North- Western Europe, North America, and Patagonia, 

 which consequently became covered by ice-sheets ; but that such 

 previous times of eccentricity, not being favoured by geographic 

 conditions, were not attended by glaciation. The recentness of the 

 Ice-age, however, which has now become generally recognised and 

 accepted by glacialists, seems to demonstrate that eccentricity was 

 not the primary cause of glaciation, and to bring doubt that it has 

 exerted any determining influence in producing unusual severity of 

 cold either during the Pleistocene or any former period. 



The alternative theory, which is accepted in this discussion as an 

 explanation of the climatic conditions bringing on and carrying off the 

 ice-sheets, has been thought out and formulated by Dana,^ Le Conte,^ 

 Wright,^' and the present writer * in America, and by Jamieson ^ in 

 Scotland. On account of its referring the cold and snowy climate 

 of the time of ice accumulation to high uplifts of the glaciated 



1 James D. Dana, Presidential Address, Proc. Amer. Assoc, for Adv. of Science, 

 Yol. ix. for 1855, pp. 23-29; Trans. Conu. Acad, of Arts and Sciences, vol. ii. 

 1870 ; many papers in the Amer. Journ. of Science ; and the several editions of his 

 Manual of Geology. 



2 Joseph Le Conte, Bulletin Geol. Soc. of America, vol. ii. 1891, pp. 323-330; 

 Elements of Geology, third edition, 1891, p. 589. 



3 G. Frederick Wright, The Ice-Age in North America, 1889, chapter xix. ; Man 

 and the Glacial Period, 1892, chapter ix. ; Amer. Journ. of Science, third series, 

 vol. xlvii. pp. 184-187, March, 1894. 



* Warren Upham, Appendix of the Ice-Age in North America, pp. 673-595 ; 

 Amer. Journ. of Science, iii. vol. xlvi. pp. 114-121, August, 1893; Bulletin Geol. 

 Soc. of America, vol. v. 1894, pp. 87-100; Geol. Mag. Dec. III. Vol. VII. 

 pp. 492-497, Novemher, 1890. 



5 Quart. Journ. Geol. Soc. vol. xviii. 1862, p. 180; vol. xxi. 1865, p. 178; 

 Geol. Mag. Dec. II. Vol. IX. pp. 400-407 and pp. 457-466, Sept. and Oct. 1882 ; 

 Dec. III. Vol. IV. pp. 344-348, August, 1887; and Dec. III. Vol. VIII. pp. 387- 

 392, September, 1891. 



