244 The American Geologist October, 1894 
ing streams, the Rainy and Winnipeg, Red and Saskatchewan 
rivers, Mowed northeasterly through a vast nearly flat plain 
and thence eastward along a great valley hounded by high- 
lands, where now we have the Hudson bay and strait. 
The drift-covered Cretaceous highland tract called the Co- 
teau des Prairies, terminating at the north, about twenty-five 
miles west of lake Traverse, in a bold headland, surrounded 
on all skies excepting the south by a nearly level expanse 800 
feet lower and about 1,200 feet above the sea, appears to have 
stood, during both the Tertiary and Quaternary cycles of 
baseleveling, in the angles between confluent streams which 
flowed to the north. Both the Tertiary and early Quaternary 
rivers from this part of the continent probably had their 
mouths on or south of the area of Davis strait; for the ab- 
sence of marine Tertiary formations from the coasts of the 
northern half of North America testifies to their having held 
a greater altitude throughout that era than now. 
Relationship of the latek Baseleveling to the Ice age. 
Flowing so great distances before reaching the sea, the riv- 
ers of both these cycles of baseleveling may have denuded 
their areas of drainage, during the first cycle very completely 
and during the second partially, to broad plains, while yet the 
altitude of the Manitoba lake region equalled or exceeded 
that of the present time. Lake Winnipeg is 710 feet and lake 
Manitoba 809 feet above the sea. New4y uplifted as a high 
plateau during the early portion of the Quaternary era, this 
north part of the continent, rising probably somewhat faster 
in the Arctic region than farther south, may have continued 
to present favorable conditions for the baseleveling of the 
Red river valley and the district of the great Manitoba lakes 
until the mean altitude of the area which became covered by 
the North American ice-sheet and its drift was 3,000 to 5,000 
feet higher than now, as indicated by the fjords and subma- 
rine valleys of our northern Atlantic, Arctic, and northern 
Pacific coasts. The culmination of this uplift appears to have 
brought so cold and snowy climate that a vast sheet of snow 
and ice was gradually accumulated, under whose weight the 
land finalty sank mostly somewhat below its present hight, 
causing the ice-sheet to be melted away, with deposition of 
its glacial and modified drift. 
