472, TRANSACTIONS OF SECTION C. 
with a prominently Cretaceous fauna of Dinosaurs, &c., and an upper 
(Pascapo) formation with a prominently Eocene fauna and flora. 
These Cretaceous and Eocene beds underlie the great plains from 
Portage la Prairie in the east to the foot-hills of the Rocky Mountains in 
the west, and throughout this distance they have a practically horizontal 
attitude. But they become thicker as they approach the Rocky Mountains. 
At the eastern flank of the mountains they are broken by a great reverse 
fault, and are overridden by limestones, &c., of Devono-Carboniferous age, 
which thus form the eastern escarpment of the mountains, while farther 
west they are included in the folds of the mountains themselves. The great 
coal areas in the mountains are of Lower Cretaceous age. 
Farther west, along the line of the Canadian-Pacific Railway through 
British Columbia, rocks of various ages, from Archean up to Tertiary, 
may be seen; but it will be more interesting to point them out as we pass 
them on our special train than to attempt any description here. 
2. The Distribution of the Ice Sheets in Western Canada. 
By Dr. A. P. CoLEMAN. 
The Ice Age began. in Canada by the extension of mountain glaciers 
in the Cordilleran region till the valleys were occupied and the ice flowed 
out upon the plains. When this ice-sheet retreated, the ice began to 
spread from the Keewatin centre, covering the plains and reaching nearly 
the foot of the mountains. In former maps of the western glaciation a 
strip was left uncovered along the eastern edge of the mountains; but it 
has been found by recent work that this is not correct, since the older 
boulder-clay from the mountains underlies the later till from the Keewatin 
Archean region. 
At present the Keewatin centre is 2,000 or 3,000 feet lower than the 
position of Archean boulders in the foot-hills of the Rockies. The 
altitudes of the different areas may have been different when the Keewatin 
ice did its work, though the region was probably not at sea-level. Many 
of the far-western erratics were transported by floating ice on ice-dammed 
lakes during the retreat of the Keewatin Glacier. 
3. The Glacial Lake Agassiz. By Warren Upnam, A.M., D.Sc. 
During the final melting of the North American ice-sheet a glacial lake, 
held by its barrier in the basin of the Red River and Lake Winnipeg, 
extended from Lake Traverse, on the west side of Minnesota, northward 
to the Saskatchewan and Nelson Rivers, and eastward on the international 
boundary to and somewhat beyond Rainy Lake. It attained thus an area 
of about 110,000 square miles, exceeding the combined areas of the five great 
lakes tributary to the St. Lawrence River. This glacial lake, named in 
1879 Lake Agassiz, bad a southwardly flowing outlet, called the Glacial River 
Warren, which took the course of the present Minnesota River, joining the 
Mississippi at Fort Snelling. 
Beach ridges of sand and gravel, a few feet high, traced by levelling 
along about 800 miles of the highest shore of Lake Agassiz, mark its stage 
of greatest extent; and other similar beaches, at many successive lower 
levels, record later stages of the lake, reduced in height by erosion of a deep 
channel along the course of the outflowing river. After the recession of the 
ice-sheet permitted drainage from the glacial lake north-eastward into 
Hudson Bay, still lower beaches were formed, until the complete uncovering 
of the area crossed by the Nelson River reduced Lake Agassiz finally to its 
present representative, Lake Winnipeg, 
