IGO 



Ci-ockville, while they have been found up the Ottawa in position and 

 elevation corresponding to Lake Ontario. 



Having climbed Mount Washington I will say that I cannot 

 conceive of any terraces on the flanks at any latitude like 2,GG5 feet, as 

 ''eported by Prof. Hitchcock, of any other origin than that of sea 

 terraces. A different conclusion could be arri\ed at on tlie hypothesis 

 of a recent change of level, whereby the region of the four great lakes 

 could be supposed to have been depressed. But I have described to you 

 the Ottawa leda clay terraces as extending northward beyond the 

 Archjean neck, which has been reared as a dividing line between salt 

 water, and the fresh waters of the pleistocene epoch. I have shown 

 that the ice phenomena of that region are superficial, and later than 

 the clays ; that a separating ridge in the sixty miles between Kings 

 Mountain and Sharbot Lake, by reason of change of level, is uutenaV)le ; 

 while the continuity of the St. Lawrence River and Ontario Lake shore 

 clays confirm these facts. If by levelling along the terraces, a change 

 of level can be shown to have occurred the facts I have given will still 

 remain to be disposed of. Such levels have been taken by Messrs. 

 Gilbert and Upham, on both sides of the American boundary line. 

 In spite of the difficulty of identification of terraces they may readily 

 establish important points connected with the pleistocene history of the 

 lakes. 



But if you would exclude the salt water sea of the lower St. Lawrence 

 from the one great fi-esh water lake which united the areas of the four 

 Canadian lakes another material must be produced that could do 

 it other than ridges or soil of the surface. An ice dam has been sus2:ested. 

 It would have lain along the region of the belt of little lakes and glacial 

 hummocks described between the Chats Rapids and Kingston. I have 

 yet to hear from any one who has ever seen such an ice dam, in any 

 of the icy regions of the globe. It must have been more than an ice 

 dam ; an ice stream which had the effect of a dam. A concentrated 

 ice stream flowing in the direction of the united upper Gatineau, 

 Coulonge and upper Ottawa rivers might well have filled the gap be- 

 tween King's mountain and the Adirondacks and so replenished the 

 melting action of warmer water, against which diminishing influence 

 no other ice dam could have maintained itselr". Such an ice dam or 



