Basins of the Great Lake*. — Spencer. 93 
through lake Huron and Georgian hay. and thence bailed 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 river). 
But the relative maximum depression of the channels, as far as 
explored, is disturbed by terrestrial warpings to be described here- 
after. 
Across the southern part of the peninsula of Michigan, between 
hills rising upon either side to bights of sometimes K00 or 1.000 
feet above lake Huron or lake Michigan, there is a valley whose 
western portion is occupied by the Grand river, and the eastern by 
a small river emptying into Saginaw bay. At the divide be- 
tween these rivers the land does not exceed 100 feet above the 
lakes. The topographic 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 direc- 
tion opposite to that of the valley, or flowing towards lake Michi- 
gan — that is. the drainage 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, lint 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 1 name the 
Hwonian. 
Other buried valleys and channels submerged could be given, 
but the}' all indicate the origin of the basins of the lakes as the 
valleys of a great river and its tributaries — a river of such high 
antiquity that the rains and rills had already ground off the sur- 
rounding 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. 
7. Th< Glaciation a/ tin region. 
At the present stage in the investigation thi> subject, can l>e 
piickly dismissed. The question whether glaciers can erode great 
*This is at the Sanitarian well at Alma. Mich., the record being Fur- 
nished by Prof. Charles A. D;ivis. 
