

B. N. A. BOUNDARY COMMISSION. 




























Here, however, it becomes broken and undefined. The Thick 
Hills near the Elbow of the North Saskatchewan, and the Red Deer : 
probably form outlying portions of this plateau, and the high g 
west of the Saskatchewan, near Fort Pitt, may be its eastern limi 
that region. 
10. This portion of the great plains was the first to emerge from tl 
waters of the Tertiary, and from those of the glacial submergence, and its 
surface may have been subject to denudation through a great part of the i 
_ two later periods of the Tertiary, as well as in post-glacial pa De ss 
Those portions of it which still remain but little modified, form table 
lands, the surfaces of which, from the horizontality of the underiying' 9 
Lignite Tertiary strata, may be in many places nearly the same as those | 
of the last deposited beds. It bears some evidence, however, of having ‘a a 
been subsequently levelled by marine action. The immense denudation — 3 3 
which has taken place by rain and rivers, is evidenced by the size and — Pe 
depth of the vallies of rivers and streams, both of pre-glacial and post- 
at . glacial age, the great ravines and gullies which have been cut, and are still 
ie extending themselves among the soft sandstones and clays of these 
ee newer formations, and the isolated plateaus and buttes, which now stand ‘a 
i far out on plains of lower level, seamed with newer systems of coulées— 
ee and gorges. Deposits belonging to the glacial period, and transported 
| boulders and gravel, are found on this highest steppe, but are not spread 
ie «| with the same uniformity as on the lower levels, and a great part of the — 
surface is based almost immediately on Cretaceous or Lignite Tortie 5 
a beds, and varies in the character of its vegetation arid appearance ~ iM mA 
" accordingly. The nature of the soil and prospective agricultural value of % 
i : this great region are too varied to allow of generalization; embracing asit — 
ie does, land along the foot of the mountains of unsurpassed fertility, and " * 
also the northern extension of the Great American Desert, with its — 







r 
ca 
- ae 
rs 
= a 
« «* * 
Ae ede 
ee 2 
H surface of sun-baked clay or sand, scarcely supporting a thin growth of ie 
" Cactus and Stipa. ey 
11. Though thus so remarkably simple and definite in its grand — Re 
a features, the interior region of the continent shows many irregularities “4 
a and exceptions in detail. The second steppe has some elevations on its an 
2 surface as high as the edge of the third plateau, and that part surrounding 
’ the Assineboine River and its tributaries, appears to have become — 
abnormally depressed, making some portions of the eastern edge of this — 
t prairie level, which overlook Manitoba Lake, more to resemble outlyers: 
i. ‘ than integral parts of it. The third steppe, though so irregular in many 

