Spencer.] tiUU [March 18, 



Discovery of tJie Preglacial Outlet of the Basin of Lak6 Erie into that of 

 Lake Ontario; with Notes on the Origin of our Lower Great Lakes, By 

 J. W, Spencer, B. A. Sc, Ph.D., F.O.8., King's College, Windsor, N. S. 



{Bead before the American Philosophical Society, March 18, 1881.) 



Summary. 



The object of this paper is to bring before the scientific world the follow- 

 ing observations, bearing on the Preglacial Drainage and origin of our 

 Great Lake Basins : 



1. The Niagara escarpment, after skirting the southern shores of Lake 

 Ontario, bends at nearly right angles in the neighborhtwd of Hamilton, at 

 the western end of the lake ; thence the trend is northward to Lake Huron. 

 At the extreme western end of the lake this escarpment (at a height of 

 about 500 feet) encloses a valley gradually narrowing to four miles, at the 

 meridian of the western part of the city of Hamilton, where it suddenly 

 closes to a width of a little more than two miles, to form the eastern end 

 of the Dundas valley (proper). This valley has its two sides nearly paral- 

 lel, and is bounded by vertical escarpments, which are capped with a great 

 thickness of Niagara limestone, but having the lower beds of the slopes 

 composed of Medina shales. On its northern side the escarpment extends 

 for six miles to Copetown ; but westward of this village it is covered with 



