44 



During this period Lake Erie did not exist as a lake, but as a val- 

 ley, traversed by a river to which the Cuyahoga, Vermillion, Chagrin, 

 &c., were tributaries. In this " glacial epoch " all the lake country 

 was covered with ice, by which the rocky surface was planed down 

 and furrowed, and left precisely in the condition of that beneath the 

 modern moving glaciers in mountain valleys. Could we examine the 

 surfaces upon which rest the enormous sheets of ice which cover so 

 much of the extreme arctic lands, we should doubtless find them ex- 

 hibiting the same appearance. 



(b) At the close of the glacial epoch all the basin of the great lakes 

 ivas suhmerged beneath fresh ivater, which formed a vast inland sea. 



From the waters of this sea were precipitated the laminated clays, 

 the oldest of our drift deposits, containing trunks and branches of 

 coniferous trees, a few fresh-water and land shells, but no oceanic 

 fossils. Parallel beds on the St. Lawrence, as shown by Prof Daw- 

 son, generally contain marine remains. It would seem, then, that this 

 was a period of general subsidence throughout the northern portion 

 of our continent, and that the Atlantic then covered a large part of 

 New England and Canada East. 



(c) Subsequent to the deposit of the blue clays, an immense quan- 

 tity of gravel and boulders was transported from the region north of 

 the great lakes, and scattered over a wide area south of them. 



That these materials were never carried by currents of water is 

 certain, as their gravity, especially that of the copper, would bid de- 

 fiance to the transporting power of any current which could be driven 

 across the lake basin ; indeed, that such was not the method by which 

 they were carried is conclusively proved by the fact, that, between 

 their places of origin and where they are now found, the blue clay 

 beds previously deposited now lie continuous and undisturbed. .By 

 any agent, ice or water, moving over the rocky bottom of the 

 lake basin, carrying with it gravel and boulders, these clay beds 

 would have been entirely broken up and removed. The conclusion 

 is, therefore, inevitable, that these immense masses of Northern drift 

 were floated to their resting-places. 



All the facts which have come under my observation seem to me 

 to indicate that, during countless years and centuries, icebergs 

 freighted with stones and gravel were floating from the northern 

 margin of this inland sea, melting and scattering their cargoes on 

 or near its southern shores. Subsequently, as its waters were grad- 

 ually withdrawn, these transplanted materifils, rolled, comminuted, 

 and rearranged by the slowly retreating shore-waves, were left as we 

 now find them, heaps and imperfectly stratified beds of sand and 

 gravel. 



(o) In the lake ridges (ancient beaches), which have been so 



