^{page 293 note 1} For evidence of this single alternation in the States of Iowa and Illinois, see McGee in Amer. Journ. of Sci. 3rd series, vol. xv. p. 241;in Nebraska, see Hayden's Keport on the superficial deposits of Nebraska for 1874; and in British Columbia, see G. M. Dawson in Q. J. G. S. vol. xxsiv. p. 122.Google ScholarGilbert, G. K. (of the.U. S. Geological Survey) writing in “Nature” of 18th January, 1883 (p. 262), observes that “in America, where thereis now great activity in the investigation of glacial phenomena, the evidence of a single interglacial period is cumulative and overwhelming, while there is no evidence whatever of more than one.“Google Scholar

^{page 294 note 1} A sketch of the country taken by Payer from Payer's Spitze (a peak 7000 feet high in lat. 73° N.) is published in the “Leisure Hour “ for Nov. 1871. Instead of the uniformlylevel pall of ice burying everything as far as the eyes of observers who have penetrated 30 miles inland upon itcan reach(and which from its elevation buries the highest of such hills as those which lie as islands uncovered by it between this ice pall and the sea, and rise to 2000 feet), in West Greenland, this view shows the snow-covered area of East Greenland aseverywhere peaked, withthe rocks in some parts protruding. A range of mountains in the furthest west that could be seen, bounded the otherwise almost boundless view, the principal peak of which range the explorers estimated to be 14,000 feet high.

^{page 295 note 1} Mr. Dawson, G. M. indeed, in his paper on the superficial Geology of the Winnipeg and Saskatchewan region (Q. J. G. S. vol. xxxi. p. 620), insists that the features of this region conflict with the hypothesis of a polar ice cap.Google Scholar

^{page 296 note 1} Amer. Jonrn. of Science, third series, vol. ix. p. 312; vol. x. p. 385; vol. xiii. p. 80; vol. xvi. p. 250.Google Scholar

^{page 296 note 2} Same Journal, vol. xvl. p. 88. His remarks are in reference to the forest growth, and not to the glaciation.Google Scholar

^{page 297 note 1} Dawson, Q. J. G. S. vol.xxxi. p. 620, et seq.Google Scholar

^{page 297 note 2} Insulated within this glaciated area, near to its south-western extremity, is an unglaciated space called “the driftless area of Wisconsin, “due to the furcation and subsequent coalescence of this extremity of the ice-sheet as it issued to the Mississippi drainage region from Lakes Michigan and Superior, which, as well as the other lakes, it filled. This small insulated area, as it does not concern my argument, I have not noticed in the text.Google Scholar

^{page 297 note 3} Mount Washington, the highest (6,293 feet), has its summit, according to Hitchcock in Amer. Journ. 3rd series, vol. x. p. 353, covered with debris transported from distances of not more than thremiles, but with “Bethlehem gneiss“ brought from a distance of twelve miles.Google Scholar

^{page 298 note 1} Otto Torrell, the Scandinavian glacialist, tried in a paper before the meeting of the American Association in 1877 (American Journal of Science, series iii. vol. xiii. p. 76) to show the contrary of this, insisting that Greenland was the source of the American ice, and observing, “that if we bear in mind the certainty that during the Glacial period the glaciers moving from the heights of Greenland towards the sea could not have formed detached icebergs as now, but must have for the time blocked up all avenues except the one of easiest escape for the immense accumulations of ice, we may easily assume that this avenue was south-westwards across British America and the north-eastern part of the United States.“As Prof. Torrell supports this view with a statement that “the ScandinavianGlacie crossed the Saltic and German Ocean, and extended its moraines into the suburbs of London, “which (without trenchingon the moo question whether the Scandinavian ice reached the Orkneys or Shetlands) my intimate knowledge of the Glacial bedsof East Anglia tells me is utterly contrary to the fact, I do not attach any weight to his view of the source of the American ice. Moreover, as explained in the text, I doubt the great volume of the Greenland ice during the Glacial period.Google Scholar

^{page 298 note 2} Same Journal, vol. xv. p. 250.Google Scholar

^{page 298 note 3} Dana in same Journal, vol. xv. p. 250. Dawson, G. W. speaks (Q. J. G. S. vol. xxxi. p. 617) of a drift occurring over the region between this western edge of the glaciated area and the Eocky Mountains, but he explains that it is drift mainly derived from those mountains, and but subordinately from the glaciated area to the east and north-east. This he attributes to ice floating in water of some kind, and it has occurred to me that such water may have originated in part from the drainage from the Rocky Mountains, which now reaches Hudson's Bay, through LakeWinnipeg, having been blocked from this escape by the Laurentian ice thus filling that and the other lakes, and in other part from the effluent water of this edge of the ice-mass; the combined water thus resulting rising above the level of the low parting between the Ked River (which now drains to Winnipeg and Hudson's Bay) and the Minnesota Eiver (which runs into the Mississippi), and so escaping by the Mississippi to the sea. Gen. Warren (Amer. Journ. of Sci. vol. xvi. p. 417) shows that the Red River once flowed this way, though he places the time of its doing so as subsequent to the Glacial period. I have, however, found phenomena in England which have been regarded as posterior to the Glacial period to be really coeva with it, and it may be the same in America.Google Scholar

^{page 299 note 1} Schott's tables, pp. 77–79.

^{page 299 note 2} See Hopkins in Q.J.G.S. vol. viii. pp. 89 to 92.Google Scholar

^{page 300 note 1} Proc. Royal Geographical Soc. for 1862–1863, p. 76; a.so (but I quote thisonly from Brown's Physics of Arctic Ice, in Quart. Journ. Geol. Soc. vol. xxvii. p. 6S1, note) Naturhistorisk Tidsskrift, 3rd series, vol. i. part 2, 1862. Of this 12 inches he estimates that only two are represented by the actual ice escape as glaciers to the sea, the rest, beyond the insignificant amount represented by evaporation, passing off by melting as water through the ice in the form of sub-glacial rivers, which boil up in copious springs of freshwater through the sea in front of the glaciers. I think, however, that perhaps it may not all pass off, and that the overwhelming of Reindeer pastures by the ice during the centuries of Danish occupation, and the indications of subsidence afforded by the position of ancient dwellings, may show that the ice is now augmenting and the land sinking under its weight. If so, this probably has been going on since the close of the Minor Glaciation, from the change in the places of greatest snow precipitation discussed in the text; and the ancient depression indicated by marine shells high above present sea-level in Greenland may possibly have been due to a similar augmentation of the ice in the interval between the Major and Minor Glaciations, to that which is thus now only in progress.Google Scholar

^{page 300 note 3} Quart. Journ. Geol. Soc. vol. ix. p. 301.Google Scholar

^{page 301 note 1} See pp. 714 and 716 of my Newer Pliocene Memoir, in Q. J. G. S. vol. xxxviii.Google Scholar

^{page 301 note 2} It seems to have originated with Grove 40 years ago, and been recnrred to by himin his Address as President of the British Assoc. in 1866. It has been made the subject of an Essay by W. Mattieu William on “ The Fuel of the Sun “, and in another form was last year advanced by C. W. Siemens. Sterry Hunt has alsosupported it.Google Scholar