GLACIAL PERIOD. Ill 



mum distribution of heat in the higher lands of our continents, while 

 famishing great oceanic areas for the suj)ply of vapor. The accumula- 

 tion of ice and snow and the j^roduction of great glaciers can occur only 

 w^here there are not only large areas of abundant precipitation, but others 

 of equally abundant evaporation. I would therefore ask the attention of 

 my fellow-workers to the facts and conclusions presented in the volume 

 referred to, and would exj^lain that I have been induced by long and 

 careful study of the phenomena, both ancient and modern, presented to 

 observation in Canada to conclude that no one cause, however potent, 

 can account for all these phenomena, and that we must invoke the com- 

 bined and successive action of glaciers, of icebergs, of field, floe and pan 

 ice, and, in short, all these glacial agencies that now operate in the north, 

 and this in connection with great and unequal changes of level, pro- 

 ducing elevation and submergence, the whole in such a way as to modify 

 climate locally, and to some extent throughout the northern hemisphere. 

 The problems presented to us by the Glacial period of the Pleistocene are 

 thus very complex, and the great error here, as in so many other depart- 

 ments of geology, has been tliat of referring the effects of various causes 

 and conditions, alternating through a considerable lapse of time, to one 

 dominant cause without reference to others equally important. The 

 time, however, is rapidly approaching when we shall no longer speak of 

 opposed glacier and iceberg theories or invoke incredible physical changes 

 to account for imaginary phenomena. I need scarcely add that our views 

 of this whole subject have been greatly modified by the demonstrations 

 that the close of the Glacial period dates only a few thousands of years 

 before our own time, and that those astronomic theories, which demand 

 a vastly greater time for their operations, are no longer tenable as the 

 cause of a glacial period. 



I may base some objections to the idea of a continental glacier as now 

 held by many in this country on a suggestive paper by Dr Warren 

 Upham * in the Bulletin of this Society, in which he institutes compari- 

 sons between Pleistocene and present ice-sheets. The present ice-sheets 

 are stated to be four: 1. Antarctic or that which fringes the Antarctic 

 continent and is probably better entitled to the name than any other, 

 but wliich differs from the supposed ice-sheets of the Pleistocene in front- 

 ing on the sea and discharging all its product as floating ice. In this, 

 liowever, it certainly resembles many of the great local glaciers of the 

 Pleistocene. 2. The great neve of Greenland, which, however, discharges 

 by local glaciers, opening on the sea. 3. The Malaspina glacier of 

 Alaska, evidently a local glacier of no great magnitude, though present- 



* Comparison of Pleistocene and preHcnt Ice-s}ieets. Bull. Geol. Soc. of America, vol. 4, pp. 

 191-204. 



