OF CENTRAL CANADA PART V. 295 



Lake Ontario, to Hamilton at the head of the Lake. Northwards 

 the ground rises in a succession of terraces to about 1,000 feet, and 

 then descends towards Lake Simcoe to about 700 feet above the level 

 of the sea. The northern edge of this Lower Silurian area, from 

 Kingston to Georgian Bay, abuts against the Archaean, gneissoid 

 region, and the junction of the Silurian limestones with the gneissoid 

 Laurentian rocks of the latter is marked by an almost continuous 

 line of small lakes. At Hamilton the ground rises abruptly into the 

 great escarpment known as the Niagara escarpment, which extends 

 from the Niagara River to Cabot's Head on Georgian Bay. West- 

 ward, the escarpment forms the edge of a broad table-land, which, 

 from an average elevation of about 1,100 feet, stretches on one side 

 to Georgian Bay (578 feet above the sea-level), and on others to Lake 

 Erie (565 feet) and the southern extremity of Lake Huron (578 

 feet). This high land is underlaid by Upper Silurian and Devonian 

 strata, and is of great fertility over the larger portion of its area. 

 The Manitoulin Islands in Georgian Bay are made up mostly of 

 Lower and Upper Silurian strata. All the other portion of the 

 Province except the remote and still imperfectly known region 

 around James' Bay, in which the strata are chiefly or wholly of 

 Upper Silurian and Devonian age, belongs essentially to the great 

 Archa3an region of Canada, and is underlaid by Huronian and Lau- 

 rentian gneissoid rocks, with a comparatively small development of 

 Lower Cambrian strata about Thunder Bay and a few other points on 

 Lake Superior. This vast Archsean region, although densely wooded, 

 is of a more or less wild and inhospitable character, and as a rule ill 

 adapted for agricultural occupation : but it abounds in mineral 

 wealth, and especially in ores of iron, copper and silver. 



From this rapid outline of the topography and general features of 

 Ontario, it will be seen that three great geological areas may be 

 recognized within the limits of the Province. A line drawn from 

 James' Bay southwards to Lake Ontario will traverse these three 

 leading areas, as shewn in the annexed sketch-section : 



SOUTH. Fig. 240. NORTH. 



With the exception of the remote and unsettled region around 



