428 Prof. Chapman on the Drift Deposits 
surface of the sphere must be considered as a close bounded by 
0 contour, or we have have 8=—1, and the equation thus be- 
comes P+S=H+2+B8B. ‘Thus, if the sphere be divided into 
two parts by a mere contour, P=2, S=0, E=0, B=0O, and 
the equation is satisfied. And in general, when B=O, then 
P+S=E+2; or writing F for P, then F+S=E+42, which is 
Kuler’s equation for a polyhedron. 
2 Stone Buildings, W.C., 
March 8, 1861. 
LXIV. Some Notes on the Drift Deposits of Western Canada, and 
on the Ancient Extension of the Lake Area of that Region. By 
Ei. J. Cuapman, Professor of Mineralogy and Geology in Uni- 
versity College, Toronto*. 
i ie following notes and deductions are the result of a 
careful examination of the Drift deposits of Western 
Canada, undertaken during the last three or four summers in an 
unsuccessful search for marine post-tertiary fossils, such as occur 
so abundantly in many parts of Kastern Canada and throughout 
the New England States. The district more especially investi- 
gated extends from the Bay of Quinté westward to the mouth of 
the Saugeen on Lake Huron, and includes the lime of country 
lying along, and immediately within, the outcrop of the Lauren- 
tian rocks north of that region. Detached observations have 
been made, moreover, at various points on the islands and north 
shore of Lake Huron; and also beyond the limits of the province, 
as in the district south of Lake Ontario, in Michigan, and along 
the southern shore of Lake Superior. 
The notes recorded here are arranged under two sections, of 
which the first comprises a collection of data, and the second a 
corresponding series of deductions. 
§ 1. Data. 
1. The first point observable, with regard to our Drift deposits, 
is the very evident fact that the rock floor on which these accu- 
mulations are spread had been extensively denuded prior to their 
deposition upon it. They cover thus an undulating and more 
or less broken surface ; and their thickness, consequently, apart 
from the denudation to which they have been themselves sub- 
jected, 1s exceedingly variable. 
2. The lowest of these deposits appear to consist of dark-blue or 
greyish clays, with thin layers of yellowish or light-coloured clay 
* Communicated by the Author, 
