424 
The geclogical character of this plateau, which forms by far the greater part 
of the Province of Ontario, affords so complete an explanation of the very charac- 
teristic inland waters of the Province, that some reference thereto will assist the 
reader in forming a conception of their arrangement. 
A line drawn from the outlet of Lake Ontario, (near Kingston) to Matche- 
dash Bay in the Georgian Bay, (near Midland in the accompanying map), divides 
Ontario into two very unequal parts. The northern part is almost entirely 
formed of rocks of the Laurentian and Huronian series, consisting largely of 
gneiss and crystalline limestones, which, although apparently altered in their 
structure, present evidence of being the most ancient sedimentary rocks, and 
have on this account beentermed Archean. They offer, however, a very different 
degree of resistance to the eroding and transporting powers of water than do the 
more recent sedimentary rocks which have not undergone metamorphosis, and 
thus, insteid of continuous river channels, we have series of irregular depressions 
and clefts converted into lakes by the accumulation of rain and melted snow, and 
connected with each other by short rapid rivers and falls. This country is 
generally densely wooded, and in many places, owing to the protrusion of the 
crystalline rocks through the surface clays, unfitted for agriculture, but neverthe- 
less there are large areas, especially north of the height of land, where the rocks 
are not exposed and which consequently furnish large tracts of arable land. 
Only two regions north of the line referred to are underlaid by rocks of more 
recent origin than the Huronian and Laurentian series. These are firstly, the © 
triangular tongue between the Ottawa and St. Lawrence Rivers as far west as a 
line drawn from Brockvil'e to Arnprior, which is underlaid by Cambrian and 
Lower Silurian strata; and secondly, the northern Paleozoic area of James’ Bay, 
a low, level and swampy region, free from rocks and lakes, extending from the 
south-west shore of the bay towards the height of land, and involving a consider- 
able part of the area traversed by the Albany and Moose Rivers. This region, 
whose steadily flowing rivers, uninterrupted by lakes, present a difference between 
high and low water mark of about ten feet, necessarily offers somewhat different 
conditions of life to the finny tribe than the Laurentian region. It is surrounded 
by a curved rim of Archzean rocks, the unyielding nature of which brings it about 
that the rivers flowing towards James’ Bay meet with a great and rapid descent 
at the point where they pour over it. The Long Portage of the Abittibe River, 
marked in the accompanying map, indicates the position of this rim at the point 
in question. It is similary sitzated in the Moose and Albany Rivers, but the 
sides of the rim converge northward to the shores of James’ Bay. 
The second and very much smaller part of Ontario is that south of the line 
described above. It is underlaid by Silurian and Devonian strata in ascending 
geological order from north to south and west, and is crossed by the great Niagara 
escarpment, an abrupt rise which extends from the Niagara River by Hamilton, 
Georgetown, etc., to Cabot’s Head in the Georgian Bay. Both east and west of 
this rise, the country, which forms a continuous tract of fertile farming land, ~ 
presents a very different aspect from the rugged landscape of the northern 
Archean region. On the east the surface is more undulating, the ground gradually 
rising from Lake Ontario in a series of ridges composed of drift materials to a 
height of some 700 feet. Some lakes, like Rice Lake and Lake Secugog, are 
situated in the midst of these drift ridges, others are situated along the line of 
junction with the Archean region to the north. To the west of the escarpment 
on the other hand, the land slopes away gently towards Lake Huron and Lake 
Erie, and although, as we shall see, important rivers find their way into both 
these lakes, yet it differs from the country to the east in the absence of smail 
inland lakes. 
