COLLIER.] 
GENERAL GEOLOGY. 
13 
eastward from Cape York. The Port Clarence limestone is known to 
be of upper Silurian age, and it is safe to presume that a large part 
of the sedimentary rocks of the York region are also upper Silurian. 
The continuity of this limestone is interrupted by several small 
LEGEND 
Sands and gravels 
Limestone and schists 
Slates 
Scale 
15 
-Geological sketch map of the York region. 
slate areas of irregular outline, and a large belt of these rocks lies to 
to the west of the York Mountains, forming the mass from which the 
greater part of the York Plateau is cut. These rocks, often so altered 
that they might more properly be called schists, are of a graphitic, 
