No. 4.] SPENCER— SURFACE GEOLOGY. 233 



to the problem of the drainage of Lake Erie. Moreover the 

 present barrier between the lakes may have quite probably been 

 increased by local elevation of the land as we find the indications 

 pointing to the Duudas valley being along the axis of an anticlinal 

 of less than one degree of dip. 



Attention has been called in this paper to the deepest portion 

 of Lake Erie being southward of Haldimand county, and about 

 the end of Long Point, and extending transversely towards the 

 Pennsylvania shore. 



So far, our remarks have been applied to Canada. If we turn 

 towards the American shore, we will see that the observations 

 made there go very strongly in support of what has been written. 



Several years since Dr. Newberry, Mr. Gilbert, and others, called 

 attention to the deeply buried valleys of the Guyahoga, Chagrin, 

 Grand, Maumee and other rivers in Ohio, which emptied into 

 Lake Erie much below their present levels. The Cuyahoga has 

 its channel buried to a depth of 228 feet below the surface of 

 Lake Erie of our time, whilst the deepest water in the neigh- 

 boring portion of the lake is less than a hundred feet. 



In Report III, of the Pennsylvania Geological Survey, issued 

 in November, 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 the 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 Pre- 

 glacial drainage shows that the upper waters of the Alleghany 

 emptied by the Cassadaga river, reversed, into Lake Erie, near 

 Dunkirk, 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. The French and other rivers now emptying 

 .-jouthward from the Conneaut basin, emptied in Preglacial time* 

 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 

 ToL. X. p 2 No. 4. 



