GLACIATION OF NEWFOUNDLAND. 71 
If we are led by such evidences as the above, to suppose that, while the ocean reached 
the eastern flanks of the Adirondacks, a freshwater sea was spread over à vast area on the 
west side of that range, a barrier must have existed between them probably consisting of 
Lower Silurian strata resting upon the low ridge of Laurentian, which forms the connecting 
link across the valley of the mountain chain. This strata having been denuded and the 
land haying gradually risen, the upper waters escaped by the present valley of the St. 
Lawrence. 
We may next suppose Newfoundland to have been depressed to the extent of 500 feet 
(which is only 135 feet more than the level of the fossils on the Ottawa). The sea must have 
reached high over the surface of Grand Pond, and all the valley of the Humber, together 
with the valley of the Indian Brook of Hall’s Bay, must have been under water, while the 
valley of the Exploits must have been a great inlet of the sea, which terminated at or near 
the extreme head of Red Indian Lake. In like manner, we may suppose all the country 
represented on the orographical map by the pale yellow shade to have been under water, 
and the land which now constitutes a single island must have been an archipelago or 
group of islands, large and small. A recent survey of the Bay of Islands, by Captain W. F. 
Maxwell, R. N., shows the approaches to the three arms of that bay and the water inside 
of the islands to be very deep; the soundings varying from 100 to 142 fathoms, while, 
within the arms themselves, about the centre, they run from 50 to 100 fathoms. Outside 
the bay for a distance of thirty miles, the water is comparatively shallow, but deepens 
again further up the gulf. The depth of the deep water within the islands, it will be per- 
ceived, nearly corresponds with the depth of the Grand Pond. Off Cape Anguille, St. George’s 
Bay, the soundings reach 100 fathoms (600 feet) over a considerable area, and farther south 
a great belt of very deep water, the soundings exceeding 1,000 feet, sweeps round Cape Ray 
within three miles, thence bearing off south-easterly. On the eastern and south-eastern parts 
of the island, the map further shews from 500 to 1,000 feet of water, keeping near the cen- 
tral parts of each bay, and a depth of upwards of 1,000 feet in Trinity Bay ; while a streak 
of deep blue, or a succession of spots in nearly every inlet, indicates a great depth, in many 
cases upwards of 600 feet. The medium blue streak off the east coast of Avalon, shews the 
present direction of the Arctic current through shallower water on either side. 
It is shown at p. 9 of the Geology of Canada that the Lac des Chats, on the Ottawa, 
and Lake Ontario are very nearly on a common level, that is 232 feet above the sea. 
The distance from the former to the foot of the Lachine Rapids is 124 miles, and from 
the outlet of the latter to the same place is between 140 and 150 miles. From Lac des Chats 
the Ottawa plunges over fifty feet of Laurentian strata by a sudden fall, and upwards of 
sixty feet more at the Chaudiere Falls, near the City of Ottawa; while on the St. Lawrence 
the descent is more gradual, the same fall being accomplished by a succession of strong 
rapids, which amount in all to 205 feet. Again, the surface of Lake Superior is 600 feet 
above the sea; that of Lake Temiscaming is 612 feet ; the distance from Montreal to the 
former is about 550 miles in an air line; while from Montreal to the latter is not over 320 
miles. Reasons have already been pointed out for supposing a great ice-sheet to have pro- 
ceeded from the north, excayating the basins of the great lakes, and grinding down the 
surface of the country between Lakes Huron and Erie; while a similar process was prob- 
ably going on simultaneously from Lakes Michigan and Superior, the ice passing over the 
