20 The American Geologist. July, isoi 
Lake Mauitolju is almost eutirel}' enclosed by drift deposits. 
From the western side of these two latter lakes a gently 
rising plain reaches to the foot of the Riding, Duck, and Porcu- 
pine mountains. 
South of the area of the lakes a plain, generally thickly covered 
with alluvium, stretches into Minnesota aiid Dakota. 
The escarpment of the Pembina, Riding, Duck, Porcupine, etc. , 
mountains may be conveniently designated the ' ' ^Manitoba escarp- 
ment, " and the beds of which it is composed are, as far as is at 
present known, of Cretaceous age. At the close of the Cretaceous 
Period these beds, which now rise in places to a hight of 1,700 or 
1,800 feet above lake "Winnipeg, must have extended a long dis- 
tance farther east, but with the advent of the Tertiary Epoch, a 
period of elevation and denudation set in and continued jvithout 
inteiTnission to the close of the Pliocene. During this period the 
great north and south valle}' was formed, on the western side of 
which now rises the Manitoba escarpment, together with the 
atferent valleys of the Valley, Swan and the Red Deer rivers. 
The history' of this region during the first Glacial period is not 
at all clear, but the second Glacial period furnishes us with an 
abundant record, from which its storj" ma}- be easih' read. 
Let us examine separately, but briefly, the ditt'erent pages of 
this record, beginning with that on 
Striation. 
At the north end of lake Winnipeg the glaciation averages S. 
2° W. , or nearl}- parallel to the shore, from William river to the 
mouth of the Saskatchewan. On Cedar lake, on its eastern side, 
the striation is S. IS'^ W. , making straight for the ridge north of 
lake AVinnipegosis, while on its western side, near the mouth of 
the Saskatchewan, the glacial striae bear S. 39° W. On lake 
Winnipegosis the striae at its northeastern angle bear S. 23'^ AV. , 
while a little farther down the east shore they have turned to S. 
iC^ W. Around the south end of the same lake they bear S. 2°- 
13° E. ; in Dawson Bay S. 42''-58° W. ; in Swan lake S. 4S°- 
53° W. ; in Red Deer river S. 68°-78° W. These three latter 
courses show a set of the glacier towards the great valleys of the 
Swan and Red Deer rivers ; while those on the south and east 
sides of lake Winnipegosis indicate a movement parallel to the face 
of the escarpment. 
In the northwestern arm oi lake ^hmitoba the strife are bear- 
