'^0 THE ICK A(JE IN CANADA. 



The lower liouMer clay (/) is dften a true iuid very 

 hard till, re,sliM(i; usually ou intensely j^laciated rock- 

 surfaces, and lilled with stones and boulders. Where 

 very thick, it can he seen to have a rude stratification. 

 Even wiien destitute of marine fossils, it shows its sub- 

 marine accunndation by the unoxidized and unwcathered 

 condition of its materials. The stria- l)eneath it, and the 

 direction of transport of its boulders, siiow u general 

 movement from X.K. to S.AV., u}> the St. Lawrence 

 valley from the Atlantic. Connected with it, and 

 apparently of the same a,u;e, are evidences of great local 

 glaciers descending into the vallev from the Laurentian 

 highlands. Tlie boulder clay of the basins of the great 

 lakes, and of the western ])lains, as well as tiiat of the 

 Missouri Coteau, seems to be of sinular ciiaracter. The 

 l)asins of the lakes are [)arts of older valleys dammed up 

 with rieistocene debris.* The ^Missouri Coteau and its 

 extensions, probably the greatest " moraine " in the world, 

 and the "terminal moraine" of the great continental 

 glacier of some American geologists, appears to me to be 

 the deposit at the margin of a sea laden with vast Htlds 

 of floating ice.f 



The lower Leda clay {(/) seems in all res])ects similar 

 to the deposits now fornnng under tiie ice in lUiHin's 

 bay and the Spitzbergen sea. The up])er J^eda clay 

 represents a considerable amelioration of climate, its 

 fauna being so similar to that of the gulf of St. Lawrence 

 at present, that I have dredged in a living state nearly all 

 the species it contains, off the coasts on which it occurs. 



* Newberry, Reports on Ohio ; Hunt, Canadian Reports ; Spencer, 

 Ancient Outlet of lake Erie, Ann. Phil. Society, 1881. 



t Report on 49th Parallel. G. M. Dawson, Paper on Superficial 

 Deposits of the Plains in the Journal of London Ceological Society. 



