12 PROCEEDINGS OF THE BUFFALO MEETING. 



altitude, giving steeper gradients and increased power of erosion to the streams. 

 The duration of the uplift, however, was not geologically long ; else the narrow 

 gorge of the Cuyahoga would have become a wide valley, and, on the borders of 

 the continental plateau, the fiord-like submarine continuation of the Hudson and 

 other rivers, and the northern and Arctic fiords, would have been widened to 

 mature valleys, with extensive lowland plains and gently sloping sides. 



During the Glacial period (which I think to have been brought on by the cold 

 and snowy climate at the culmination of the uplift), the land, under the burden of 

 its ice-sheet, was isostatically depressed, so that when the consequent return of a 

 warm climate on the borders of the ice melted it away the country was somewhat 

 lower than now. By this northern differential depression the region of the Lauren- 

 tian lakes became tributary to the Saint Lawrence, which before the Ice age, as I 

 think, had received its farthest supplies from the Champlain and Ottawa valleys. 



In the ensuing moderate re-elevation from the Late Glacial or Champlain subsi- 

 dence, the basins of the four great lakes above lake Ontario lacked only a little 

 more northeastward uplifting to turn their drainage again to the Mississippi and 

 gulf of Mexico by discharge from lake Michigan at Chicago along the course of the 

 outlet of the ice-dammed lake Warren. If the east end of the lake Erie basin 

 were raised only about 40 feet higher (a small fraction of its actual uplift from the 

 Champlain depression), or, conversely, if the southern part of the Michigan basin 

 should sink 40 or 50 feet, the Niagara river would cease, and the waters of these 

 four upper lakes would pour along the Des Plaines and Illinois valleys. 



Deposition of glacial and modified Drift in Cuyahoga Valley and Lake 



Erie Basin. 



The great depth of erosion by the preglacial Cuyahoga river shows that the 

 Tertiary river of the lake Erie basin had its course on a land surface which is now 

 covered and raised, probably for the greater part from 200 to 400 feet, by the depo- 

 sition of glacial and modified drift during the Ice age. The topographic irregu- 

 larities of the preglacial Erie valley are thus largely enveloped by the drift, which 

 forms a very level expanse beneath the shallow lake. The relationship of deep 

 drift deposition on the valle) 1, lowland, while the contiguous uplands, as in the 

 vicinity of Cleveland, bear little thickness (as 5 to 20 feet) of drift, is paralleled by 

 the same conditions in the deep drift, mainly till, in large part 200 to 300 feet thick, 

 in the valley of the Red river of the North, forming the vast flat plain that was 

 covered by the glacial lake Agassiz. while the Cretaceous highland of the Pembina 

 mountain, next west of the valley plain and glacial lake area, bears usually no 

 more than from 5 or 10 to 25 or 50 feet of drift. The ice-sheet exercised a selective 

 power to deposit much drift in certain valleys and lowlands within a few hundred 

 miles of its outer limits, although on the adjacent hills, plateaus, and bluffs it 

 parted with little drift, its work there being rather erosion than deposition. 



Owing to the abundance of water in the seams and beds of stratified gravel and 

 sand (modified drift) which occur in the lower half of the drift-sheet at Cleveland, 

 the accompanying deposits of till in those parts of the well sections, perhaps less 

 clayey and more sandy and softer to bore than the higher parts of the till, are apt 

 to escape the attention of the workmen, who therefore probably report in some 

 cases a larger amount of sand and gravel, and less till or clay, than is the actual 

 character of the section. In the Standard Oil Company's well, at least, of which a 



