Great Lake Basins of the St. Lawrence. 279 
twenty-seven miles back from the lake. Farther eastward 
on the Midland railway, in rear of Whitby, clay ridges are 
met with at twelve miles, attaining 649 feet, at fourteen 
miles 781 feet, and at thirty-three miles 674 feet. On the 
Port Hope section, further eastward, the heights are some- 
what less. But let us not be led astray. Being so much 
higher than other ridges surrounding the lake, it is clear 
that the underlying Hudson River, Utica and Trenton 
strata, have been elevated during or since the deposition of 
these clays, sands and gravels, and in a direction roughly 
parallel with the lake. These superficial deposits obscure 
the strata, but this elevation, continued in a line towards 
Lake Huron, is noticeable on a greater scale at and beyond 
the townships, where it strikes the Niagara escarpment, 
whose summit near Dundalk station, on the Toronto, Grey 
and Bruce railway, has a height of 1,462 feet above Lake 
Ontario, and 1,127 feet above the Georgian Bay. 
On the south side of Lake Ontario, where the subsequent 
elevation has been less than on the north side, an extended 
ridge of 188 feet has been thrown up. The American geo- 
logists have observed a gradual rise of 130 feet in this ter- 
race, from the western end of Lake Ontario to Oneida Lake, 
and a rise of 170 feet more from Oneida Lake north to 
Jefferson County, beyond which it was not observed. This 
would imply a previous depression, increasing in depth 
with the south-easterly and easterly sides of Lake Ontario, 
and would show that its waters, now deeper towards the 
south-eastern end, were relatively more so in certain pre- 
vious periods of the lake’s history. The present levels have, 
as indicated, been largely influenced by the greater eleva- 
tion on the northern than on the southern side, causing the 
waters to be thrown more towards the southern side. 
At this period the outlet of the lake at the Thousand 
Islands was undoubtedly crossed by the Adirondack Moun- 
tains in a broad, rugged, irregular ridge, now partly de- 
pressed under the water to a maximum depth of about 250 
feet. Some sand deposits occur towards Rockport, near 
Brockville, and in rear of Kingston, and may indicate the 
20 
