528 DK. J. W. SPENCER ON THE ORIGIN OF THE 



plains sliow the absence of rock along deeply-cut valleys to far below 

 the level of the upper lakes. Upon the western side of this chain 

 of borings, but a few miles distant, there is the Niagara escarpment. 

 Upon the eastern side of Lake Simcoe the country is covered with 

 flat limestones, rising to 150 feet above that lake. From the known 

 absence of rocks along the line of borings and stream excavations, 

 between a high mountainous escarpment upon one side and a rocky 

 floor upon the other, and from these borings reaching to 200 feet or 

 more below the upper lakes, without penetrating the Drift but stop- 

 ping in quicksand, there has been discovered the existence of the only 

 channel of antiquity which could now draw off the waters of the upper 

 lakes, if the Drift were removed. Although none of the borings have 

 reached the original rocky floor, yet the depth of the buried valley 

 is suggested by the channel close upon the northern side of Lake 

 Ontario, now submerged to 474 feet, which is deep enough to drain 

 the last drop of water out of Lake Huron. 



We have now found one continuous channel from Lake Michigan 

 through Lake Huron and Georgian Bay, and thence buried beneath 

 Drift deposits until it is again recognizable throughout nearly the 

 whole length of Lake Ontario, being joined at the western portion 

 by an ancient outlet of the Erie Valley (the ancient Erigan Kiver). 

 But the relative maximum depression of the channels, as far as ex- 

 plored, is disturbed by terrestrial warpiugs to be described hereafter. 



Across the southern part of the peninsula of Michigan, between 

 hills rising upon either side to heights of sometimes 800 or 1000 feet 

 above Lake Huron or Lake Michigan, there is a valley whose western 

 portion is occupied by the Grand lliver, and the eastern by a small 

 river emptying into Saginaw Bay. At the divide between these 

 rivers the land does not exceed 100 feet above the lakes. The topo- 

 graphic features of the valley show its original opening as having 

 been into the Huron Valley by Saginaw Bay ; but a considerable 

 proportion of the modern drainage is in a direction opposite to that 

 of the valley, or flowing towards Lake Michigan — that is, the drain- 

 age has been reversed. The maximum depth of the western portion 

 of this buried valley is not known, but there is an absence of rock, 

 as shown in several borings, to between 100 and 200 feet below the 

 lake-level. But farther east in this trough there are several deep 

 wells, in one of which the Drift is 500 feet below the floor of the side 

 of the valley, or 350 feet below the surface of Lake Huron*. Hence 

 we have established the great depth of the buried valley between 

 the southern part of Lake Michigan and Lake Huron, whose ancient 

 river I name the Huronian. 



Other buried valleys and channels submerged could be given, but 

 they all indicate the origin of the basins of the lakes as the valleys 

 of a great riverand its tributaries — a river of such high antiquity that 

 the rains and rills had already ground off the surrounding hills to 

 broaden the valleys. But for all this evidence, there are now rocky 

 barriers forming an apparent obstacle in the way of a complete 

 solution of the problem. 



* This is at the Sanitarian Well at Alma, Mich., the record being furnished by 

 Prof. Charles A. Davis. 



