Vi I'llKKACK. 



iiccouiit llic ;ii,f('ii( V ImiiIi of land ice and M(»a-l)(ini(' ice in 

 many forniH, alon^' with rejiuatod and comiilcx clevation.s 

 and dcprcssioiiH of lar^a' |i(ii'lii)ns of thu continent, in 

 order to account for tlie eflects observed. He is disposed, 

 however, to seek for the causes of changes of elinuite 

 rather in n'eological and geographical agencies than in 

 astronomical vicissitudes, some of which arc too slow and 

 uncertain in tiicir operation, and others altogether con- 

 jectural. Such views are less sensational than those which 

 invoke vast and })ortcntous exaggerations of individual 

 phenomena, hut they are likely, in the end, to commenil 

 themselves to serious thinkers, especially when they are 

 confirmed hy the facts observed in the regions which arc, 

 of all others, best suited for the study both of extinct and 

 recent ice-action. 



The basis (»f the work rests on the observations of the 

 author, l»ut reference will be made to tlu; large and ini- 

 j)(jitant contributions of Dr. (}. M. Dawson, Dr. r>(dl, 

 Dr. Ells, Mr. Whiteaves, Mr. Chalmers, .Mr. Low, Dr. 

 Spencer, Mr. McConnell, ]\Ir. llichardson, I'rof. Yule Hind, 

 Lieut.-C'ol. (Jrant, Dr. (J.. I. I linde, and others, whose names 

 will be fouutl in the subseijucnt pages as workers in the 

 Pleistocene geology of Canada. 



J. WAI. J)A\VSON. 



McGiLL COLLECE, 



MONTIIEAL, 1893. 



