1881.] O^i [Spencer. 



rior can only be explained as having in part been produced by water, 

 running in one direction or the other, as the St. Louis river now empties, 

 at Duluth. 



That the other lakes are not occasioned by a geological depression or 

 elevation can be easily seen, as they are exclusively excavated from strati- 

 fied rocks lying almost flat, perhaps dipping in no place at higher angles 

 than 40 feet in a mile. 



The North channel and Georgian bay of Lake Huron belong to a sepa- 

 rate category from the rest of the lakes. I do not deny, as far as Lake 

 Ontario and the north-eastern half of Lake Huron are concerned — both of 

 which are excavated at the junction of hard and soft strata and parallel 

 with their trend — that they might have had the direction of their first 

 rivers determined by continental elevation. Yet, in no other respect are 

 these lakes now occupying geological valleys. 



Dr. Newberry is of the opinion that the valley of Lake Michigan was 

 separated from that of Huron at the Straits of Mackinac, even at a com- 

 paratively recent period. I concur with this view entirely. Lake Michi- 

 gan is 23 fathoms deeper than Lake Huron, and therefore could in no 

 natural way have ever been entirely drained by the latter lake. There is 

 no evidence of local subsidence, and the glacier theory is absolutely unten- 

 able, as will be seen further on. In the Beach Epoch of the Ice Age this 

 separation seems to have existed, as it is stated that the highest beach north 

 of Lake Michigan is 65 feet, whilst that on the island of Mackinac is more 

 than 250 feet above these waters. We know that there are several corres- 

 pondingly high beaches along the margins of the basin, including the three 

 great lower lakes. 



Thus we can cut off the two western waters of the great chain of Ameri- 

 can lakes from our subject and leave them for future inquiry. 



Whether the above named outlets of Superior and Michigan are suffi- 

 ciently deep to have drained their basins, at the time when we know that 

 the Mississippi valley was several hundred feet higher than at present, re- 

 mains to be shown. 



The writer will now deal with those waters to the eastward, and see 

 what difficulties have been removed and what still remain, for Lake On- 

 tario is nearly a hundred leet deeper than the deepest sounding of any of 

 our upper lakes. 



Dr. Newberry prophesied that an outlet for Lake Erie into Lake Ontario 

 would be discovered near the Welland canal. This outlet in an unexpected 

 position I have discovered, and in a position which explains more perfectly 

 the cause of the topography of Lake Ontario than any that could have 

 been discovered forty miles to the eastward. Moreover, I have shown that 

 its depth is not only sufficient to empty Dr. Newberry's deep Cuyahoga 

 (228 feet below Lake Erie), or the ancient rivers, worked out by Mr. Carll 

 (the most systematic study of fluviatile geology that has been done on this 

 continent), but also sufficiently deep to empty the deepest waters of Lake 

 Huron into Lake Ontario. 



