210 A POPULAR EXPOSITION OF THE 
strata; whilst the “grey band” at the top of the Medina sub- 
division proper, stands out in many places as a distinct terrace below 
the sloping bank formed by the out-cropping but debris-covered 
edges of the Clinton beds. Further to the west, the formation ig 
seen in the Manitoulin Islands, Some of the more instructive expo- 
sures occur at Queenston, and in the gorge of the Niagara river; 
at the Welland Canal in Thorold ; at St. Catherines; near Jordan in 
Louth township; on Stoney Creek, in Saltfleet; at Hamilton; Wel- 
lington Square ; Dundas and its neighborhood; Waterdown in East 
Flamborough ; Georgetown; Esquesing; on the River Credit in the 
township of Caledon; on several creeks in Nottawasaga; at Owen 
Sound and on the Sydenham River; and at Cape Commodore and 
along part of the adjacent coast up to Cabot’s Head. 
In Eastern Canada, the Medina and Clinton formation has not been 
definitely recognised; but Sir William. Logan states that an escarp- 
ment of red shales overlying the Hudson River series, on the south 
shore of the St. Lawrence, between the rivers Nicolet and Gentilly, 
together with another restricted patch of a similar character, in that 
district, may very probably be referred to the Medina division. 
The only important economic materials belonging to the formation, 
are derived from the Grey Band at the top of the Medina beds, and 
from a dark dolomitic limestone of the Clinton subdivision. The 
former yields an excellent building stone, and also grindstones of good 
quality, (Hamilton, Dundas, Waterdown, Georgetown, &c.,); whilst 
from the latter, about Thorold and St. Catherines more especially, a 
strong water-lime (known as Thorold cement) is largely manufactured. 
The Niagara Formation :—The group of strata thus named, in- 
cludes, in Canada, the upper portion of the Clinton subdivision ag 
recognized by the geologists of the New York Survey, together with 
Fig, 213.—Pentamerus oblongus and Internal east. 
