304 I:. BELL — GLACIAL PHENOMENA IN CANADA. 



over a glacier. There are various other strong objections to the theory of 

 an ice dam, which cannoi be discussed within the limits of this paper. 



If, on proper investigation, it should turn out unlikely that the water of 

 Lake Asassiz was held in its place by earth barriers in conjunction with a 

 higher general level of the continent to the east, then we shall probably find 

 that this ancient lake was a land-locked hay of fresh or nearly fresh water 

 on the Bame level as the former extension of Hudson's hay. Had the conti- 

 nent been Blightly elevated to the eastward, and had the north end of Hudson's 

 bay at that time been about 1,000 feet higher than at present, relatively to 

 the narrow divide between Long lake and Lake Superior 1,0(10 miles to the 

 smith, the fresh water which we have supposed would then fill this great 

 basin might easily have been on the same level with Lake Agassiz, and the 

 latter would then have been a mere hay of the former. A whitish clay of 

 similar character i- spread widely over both areas : and it is significant that 

 no marine shells are to be found in any of the post-Tertiary deposits in either 

 of these area- until we have descended to within 500 feet of the sea-level on 

 the Attawapishkal river, and 200 feet lower on the various branches of the 

 Moose river at a distance of 200 miles to the south. The shells are found in 

 similar stratigraphical positions in both cases, and their difference in level 

 corresponds with the rate of slope (one foot in the mile) which would exist 

 had the supposed relative change of levels occurred. 



Upward Movement of Bowlders. — The elevation of bowlders from lower to 

 higher levels is a curious phenomenon in connection with drift transporta- 

 tion. In the lake peninsula of the province of Ontario, the debris of the 

 Hudson River and Niagara formations has been carried westward in great 

 quantities and scattered over the surface of rocks which are higher both 

 geologically ami geographically. In the valley leading westward from the 

 head of Lake Ontario, the ice-grooves are plainly seen on the rocky walls 

 on either side sloping gradually upward; but to the north of this valley 

 there i- an almost continuous east-facing precipice all the way to Georgian 

 bay, which the ice-sheet would require to surmount. The Silurian table-land 

 above this precipice slopes gradually upward, as we go north, from about 

 •101) feet above Lake Ontario tO Upwards of 1,500 feet over the s:une level 



when it reaches Georgian bay and forms the Blue Mountains. Laurentian 



bowlders, from the comparatively low region north of Georgian bay, are 

 found everywhere upon this table land. 



In the chapter on superficial geology in the "Geology of Canada" (1863, 

 page 894 . I Btated, from my own observations, that "bowlders of Lauren- 

 tian rock- are found in considerable numbers scattered over the high table- 

 land of western Canada south of Georgian buy. A portion of this region 

 attains an elevation of 1,7<'»<» feet above the sea, and much of it is higher 



than the Laurentide hills, to the north, from which the bowlders have been 



