Robh on Superficial Deposits of Canada, 383 



boulders. Throughout Lower Canada, and as far west as King- 

 ston, the relative age of these deposits has been determined by 

 appropriate fossils of recent or existing species ; and although 

 these are wanting in the Upper Province, the analogy is presumed 

 to be established by other characteristic features. The fact to 

 which I would desire to call your attention, and which I am not 

 aware of having been previously observed, is that the older forma- 

 tion prevails almost exclusively in Western Canada on the elevat- 

 ed platform bounded on the east and north by the Niagara es- 

 carpment, which sweeps in a bold and abrupt manner from the 

 Niagara river round the head of lake Ontario, and northwards to 

 Cabot's head on Lake Huron, forming a very marked feature in 

 the physical geography of the Province. The whole of the coun- 

 try, for a great distance to the east of this line, and especially to- 

 wards the base of the escarpment, is thickly strewn with sand, 

 gravel and boulders of Laurentian origin ; while to the west these 

 are of very rare occurrence, and are replaced by materials evident- 

 ly derived from the disintegration of the underlying limestone 

 rocks. From the Niagara escarpment westward to the height of 

 land near Woodstock, this difference is less marked than from 

 that point still farther west to the shores of Lake Huron. The 

 influence which I would draw from these facts is one which cor- 

 roborates the view which has been entertained by Sir Charles 

 Lyell and others, who have examined the physical geography of 

 Canada ; namely that the contour of the fundamental rocks of the 

 country has been impressed upon it at an epoch long anterior to 

 glacial or drift period ; and that the elevated platform of the west- 

 ern peninsula, if not actually above the level of the sea at that 

 period, was sufficiently high to resist the intrusion of the ice is- 

 lands charged with the debris of the Laurentian and other more 

 ancient northern rocks, which would be drifted by the glacial cur- 

 rents from the north-east. 



The chemical composition of the drift clays of the more west- 

 erly parts of the province, as compared with those of the east 

 offers a remarkable corroboration of this view. By the analysis of 

 Mr. Hunt, a specimen of the sub-soil clay from a district west of 

 London, and which may be taken as an exponent of the consti- 

 tuent elements of the clays of the whole western district, yielded 

 not less than 29.40 per cent of carbonate of lime ; while a similar 

 specimen from the Niagara district gave only 15.30 per cent. 

 In fact, in some of the few places in the west where the rocks and 



