276 Reviews — Sir J. W. Datcson — Canadian Ice- Age. 



obviously due to atmospheric and river erosion during the Pliocene 

 period, supplemented by the flow of cold ocean currents over the 

 American land during submergence ; so that the lake basins are 

 of the same nature as the deep hollows which prolong the mouths 

 of American rivers beneath the ocean along the American coast. 



The third and fourth chapters discuss the physical and climatal 

 conditions of the Glacial period in Canada. 



Drawing a map of North America in the Pleistocene period, Sir 

 William Dawson commemorates some of his contemporaries by 

 giving their names to physical features of the period. " The great 

 southern bay at the bottom of which lies the ' terminal moraine ' 

 may bear the name of Dana ; the strait leading to the north-east, 

 where the St. Lawrence now flows, may be Upham Sti-ait ; the great 

 western opening may well be called Chamberlain Sound ; and the 

 northern bay filled with ice, in the region now occupied by Hudson's 

 Bay, may be the Gulf of Wright. The great islands will be 

 respectively Cordilleran and Laurentide lands, fit companions to 

 Greenland ; and the smaller eastern island, Appalachia Infelix." 



But although the author uses the expression " terminal moraine," 

 he urges that the existence of an ice-sheet which could have formed 

 it is a physical impossibility, because there could not be sufficient 

 evaporation and precipitation to afford the necessary snow in the 

 interior ; and secondly, because there is evidence of a depression 

 which admitted Arctic cun-ents through gaps in the Laurentian 

 watershed, and down the great plains between the Laurentian area 

 and the Eocky Mountains, as well as into the valley of the St. 

 Lawrence. This does not in any way affect the author's belief in 

 the great local glaciers described by Dr. G. M. Dawson, which 

 occupied the Cordillera of British Columbia and discharged into the 

 Yukon Valley, into Puget Sound, and into the Pacific. The former 

 existence of glaciers on the Laurentian axis is accepted on the 

 evidence from the Notre Dame region and the central districts of 

 Newfoundland. The great V-shaped Laurentian axis is stated, on 

 the evidence of the glacial striae, to have thrown off ice on the 

 south-east to the St. Lawrence Valley, and to the south-west towards 

 the great plains, and to have poured its ice into the interior of 

 Hudson Bay and the Arctic Sea. There is some evidence of a 

 terminal moraine along the middle of Hudson Bay, which may 

 have belonged to the inter-Glacial period. 



The striation of the rocks at lower levels is attributed to the 

 grating of pebbles included in shore-ice upon the rocky floor beneath, 

 as the ice moved with the tide ; this conclusion being based mainly 

 on the observations of the late Dr. John Eae and of Captain Feilden, 

 in the Arctic regions. The longitudinal direction of the striee is 

 attributed to the drifting of the ice backward and forward with 

 tidal currents. It is stated that the striation produced by the sea 

 is always accompanied with much smoothing and polishing, that the 

 striation is not quite uniform in direction and often presents two 

 sets of strias, while land glaciers usually produce deep grooves as 

 well as stria3 which are more uniform in direction. It is fully 



