[40] R. D. Salisbury: Physical Geography of the Pleistocene, in Outlines of Geologic History, by Willis, Salisbury, and others, 1910, p. 265.

[41] The Quaternary Ice Age, 1914, p. 364.

[42] For fuller discussion of climatic controls see S. S. Visher: Seventy Laws of Climate, Annals Assoc. Am. Geographers, 1922.

[43] Many of these alterations are implied or discussed in the following papers:

  1. F. W. Harmer: Influence of Winds upon the Climate of the Pleistocene; Quart. Jour. Geol. Soc., Vol. 57, 1901, p. 405.
  2. C. E. P. Brooks: Meteorological Conditions of an Ice Sheet; Quart. Jour. Royal Meteorol. Soc., Vol. 40, 1914, pp. 53-70, and The Evolution of Climate in Northwest Europe; op. cit., Vol. 47, 1921, pp. 173-194.
  3. W. H. Hobbs: The Rôle of the Glacial Anticyclone in the Air Circulation of the Globe; Proc. Am. Phil. Soc., Vol. 54, 1915, pp. 185-225.

[44] W. B. Wright: The Quaternary Ice Age, 1914, p. 100.

[45] The description of the distribution of the ice sheet is based on T. C. Chamberlin's wall map of North America at the maximum of glaciation, 1913.

[46] Chamberlin and Salisbury: Geology, 1906, Vol. 3, and W. H. Hobbs: Characteristics of Existing Glaciers, 1911.

[47] S. S. Visher: The Geography of South Dakota; S. D. Geol. Surv., 1918.

[48] W. H. Hobbs: Characteristics of Existing Glaciers, 1911. The Rôle of the Glacial Anticyclones in the Air Circulation of the Globe; Proc. Am. Phil. Soc., Vol. 54, 1915, pp. 185-225.