No. 2.] SPENCER — PREGLACIAL OUTLET OF L. ERIE. 75 



the rock beneath the drift-bed of the river is below the lake level, 

 on the margin of the ancient valley. 



Having observed the connection between the Dundas valley, 

 Grand River and Lake Erie, it dawned on me that I had estab- 

 lished the knowledge of a channel having a very important bearing 

 on the surface geology of the lake region. It now became 

 apparent that Lake Erie had flowed by the Grand River (reversed) 

 to a point west or north-west of Seneca, and thence by the Dun- 

 das valley, into Lake Ontario ; also that the upper vvaters of the 

 Grand River, previously discovered as passing down the Dundas 

 valley, were really tributary to the outlet of Lake Erie, and joined 

 it somewhere south of Harrisburg; and that the basin between 

 Brantford (and the Grand River of to-day) and the Great 

 Western Railway, at Copetown, formed an expanded lakelet 

 along the course of the ancient outlet of Lake Erie, scooped out 

 of the softer rocks of the Onondaga Formation before noticed. 

 As the waters excavated a bed in a deeper channel, of course 

 this lakelet would become an expanded and depressed valley, 

 such as we often see amongst the hills of drift, at a short distance 

 westward of Dundas. Possibly the Grand River divided and flowed 

 around an island, the western side of which is occupied now by 

 the town of Paris. At any rate, Neith's Creek, at that town 

 formed a large tributary to the river then flowing down to Lake 

 Ontario. 



Aloug the course from Cayuga to Lake Ontario all obstacles to 

 the outlet of Lake Erie appear to be removed. But along the 

 present course of the Grand River, eastward of Cayuga, the waters 

 flow over Corniferous limestone. But this difiiculty is removed 

 on observing that the river, filled with drift, approaches Lake 

 Erie to within a direct distance of about six miles, but at this 

 place it leaves its southward course and also its conspicuous valley 

 and flows eastward, in the same manner as the Niagara River, 

 above the Whirlpool, left its old choked-up outlet by the valley 

 of St. David, and cleaned out a new channel for itself through 

 several miles, in hard rock, from Queenstown southward. 



We have seen that the Grand River bed is near the eastern 

 margin of its ancient valley at Cayuga. From northward of this 

 town at about half a mile to the westward of the river, a deep 

 depression in the drift indicates the deeper portion of the ancient 

 river as it left the modern channel direct for the Lake Erie basin. 

 Also along this route the hard rock is known to be absent to a 

 depth below the surface of Lake Erie. 



