358 A. p. COLEMAN GLACIAL PERIODS AND GEOLOGICAL THEORIES 



the Labrador ice-sheet must have completely vanished. It may be added 

 that the Labrador sheet was the largest known in the Pleistocene ice age. 



The strong proofs of important interglacial periods in the states to the 

 south, brought forward by Professor Calvin and others, reinforce the evi- 

 dence from Ontario; and the same is true of the western states, where 

 Mr W. W. Atwood demonstrated the occurrence in the Uinta mountains 

 of two glacial periods separated by a long interglacial time."*^ 



It is interesting to find this evidence corroborated from the Andes in 

 South America, as shown by Dr Hans Meyer, who has found two great 

 extensions of the ice separated by a long interglacial period in Equador ;** 

 and by Professor Tight, who found proofs of no less than three inter- 

 glacial- periods near Ilimani and Sorata, in the Bolivian Andes. From 

 Patagonia also Doctor Moreno reports two ice ages and an interglacial 

 period in which neo-mylodon existed.*^ 



In Europe Professor Penck and others have demonstrated several inter- 

 glacial periods in the Alps, while Dr James Geikie makes a strong case 

 for as many interglacial times in Great Britain and northern Europe.*'' 

 To what extent Mr Lamplugh*' and Doctor Geinitz*^ have invalidated his 

 arguments the present writer can not venture to decide. 



Doctor Bogaliibow's account of an important interglacial period in 

 central Eussia lasting, as estimated, from 12,000 to 20,000 years, and 

 including an earlier time of forest growth and a later one of steppe condi- 

 tions, can hardly be brushed aside as of no weight.*^ In Australia, too, 

 the glacial deposits on mount Kosciusko are of two ages, with an inter- 

 glacial period between.^" 



It should be kept in mind that negative evidence is of very little value 

 as compared with positive evidence in a matter of this kind, since all 

 records of an interglacial period are apt to be swept away by the oncoming 

 of later ice-sheets. This is particularly true in the central areas, where 

 the surface is often scoured bare to the solid rock. Interglacial deposits 

 at any distance within the margin of the ice can only be preserved under 

 special conditions, such as the filling of an old river or lake valley or the 



'•' Journal of Geology, vol. xv, no. 8, pp. 795, etc. 



** La Geographle, vol. xv, no. 1, p. 62, In den Hocli Anden von Equador. (Review.) 

 ^" Royal Geographical Journal, vol. xiv, pp. 368-370. 

 <" The Great Ice Age. 

 " British Association, 1906, pp. 532-558. 



*^ Neues Jahrhuch fiir Mineralogie, Beilage, band xvi, 1903, pp. 1-98. 

 '" Zur geologischen Geschichte des Gouvernements Kalugo in der Glazialperiod. Mos- 

 cou, 1905. 



"" Australian Association for the Advancement of Science, 1902, p. 204. 



