1881. J *J^*J (Spencer. 



In Report III, of the Pennsylvania Geological Survey, issued in Novem- 

 ber, 1880, Mr. John F. Carll published excellent maps of the Preglacial 

 drainage of that State and the neighboring portions of the adjoining States. 

 This report on the Preglacial rivers is the result of five years' labors in the 

 oil regions, and many of Mr. Carll's results have been derived from the 

 facts made known by the borings for mineral oil. 



Besides calling attention to the very deep valleys of erosion amongst the 

 mountains, Mr. Carll has shown that in the oil regions the river valleys 

 are frequently filled with drift to a depth of from 200 to 450 feet. In fact, 

 nearly all the present rivers flow over beds deeply filled with drift. The 

 map of the Preglacial drainage shows that the upper waters of the Alle- 

 gheny emptied by the Cassadaga river, reversed, into Lake Erie, near Dun- 

 kirk, and had for tributaries many other streams now flowing southward ; 

 for example, the Conewango. These streams drained an area of 4000 

 miles, which now sends its surplus waters to the Ohio river. Again, the 

 French and other rivers, now emptying southward from the Conneaut 

 basin, emptied in Preglacial times into Lake Erie, westward of Erie city. 

 Again, the Chenango, Connoquenessing, Mahoning and other tributaries 

 of the Beaver river (itself now emptying into the Ohio) flowed northward, 

 by the Mahoning river reversed, into the State of Ohio, to near the sources 

 of the Grand and Cuyahoga rivers. Hence Mr. Carll did not continue its 

 course, on the map, but from the study of the levels and character of the 

 country, as described by the Geological Survey of Ohio, I have connected 

 it with the Grand river of Ohio, as represented on my map. Thus we 

 find three large areas now flowing southward formerly emptying into the 

 Lake Erie basin. 



The deepest portion of Lake Erie is between these ancient river mouths 

 and the ancient debouchement of the Erie drainage by the Grand river of 

 Ontario, as described in these pages. 



Thus we have shown a consecutive system of drainage of the former 

 waters of the buried channels into Lake Ontario, and thence running along 

 the foot of the submerged escarpment of the latter lake to its eastern end, 

 receiving the Genesee and other large rivers along its course. In a portion 

 of the present notes, the writer will endeavor to make known still further 

 the buried channels of Ontario, which exist between Lakes Huron and 

 Erie when treating of the origin of these lakes. 



The remaining portion of this paper will be devoted to the subject of the 

 origin of our great lakes. The writer does ijot wish to enter here into the 

 discussion of the drift deposits, and their origin at the present time, but to 

 reserve it until the final report on the surface geology of the Western End 

 of Lake Ontario. Yet the facts brought to light in this study have an iiu- 

 portant bearing on the great controversy of the Glacial Drift, ana lead one 

 to the conclusion that the Ultra-Glacial theorists stand on uncertain grounds. 



V. Origin of our Lower Gre.\t Lakes. 

 On a former page of this paper attention has been called to Prof. Win- 

 chell's observations of an outlet from Lake Supsrior by way of Little Bale 



