
aa 
144 _B. N. A. BOUNDARY COMMISSION. 
sufficient to vindicate the character maintained through the whole of the 
Cretaceous period by the Rocky mountain region—that of deposit by more Ay 
rapidly moving waters. West of this place, the beds of the Fort Pierre — 
group are not seen in the vicinity of the Boundary-line, though I am of 
opinion, from the rapid southward slope of the country toward the 
Missouri Valley, that these beds of the Cretaceous must again come to 
the surface not far south of the forty-ninth parallel. The Missouri, it~ 
would seem, flows for the upper part of its course in a trough excavated 
in Cretaceous beds, of which the southern part of the Lignite Tertiary, — 
met with on the forty-ninth parallel, forms the northern edge. 
351. The character impressed on the face of the country, whenever — 
the beds of No. 4 immediately underlie the surface, is unfavourable in 
the highest degree. Without the intermixture of foreign material, the 
debris of these rocks seems scarcely capable of supporting vegetation. 
Their fine unctuous character prevents any drainage from below, and the 
plains based on them, alternate with the season, from the condition of 
soft tenaceous mud, to that of hard white sun-cracked clay. I have 
frequently noticed spots poached up by the buffaloes in their spring 
migration, consolidated by the heat and drought of summer to such an 
extent, that the passage cf twenty or thirty loaded waggons will not 
suffice to form a level trail. These clays appear also to want the 
chemical ingredients of a good soil. Calcareous matter is generally 
almost entirely absent, and from the small quantity of organic remains, 
and the refactory nature uf the shales under the blow-pipe, phosphates | 
and alkalies are probably deficient, the felspar being, to a great extent, 
kaolinized. The saline waters of springs issuing from these clays, 
impregnate the soil of the low grounds and vallies, and produce condi- _ 
tions favourable to the growth of Sulicornea, Obione, Sarcobatus, &c., 
while the higher plains are the most perfect deserts met with on the 
forty-ninth parallel, and are often almost destitute of vegetation; or, 
sparingly covered with Cactus and Stipa. 
352. Dr. Hayden, in treating of this group, writes :—“This forma- 
tion is the most inportant one in the Cretaceous system of the North- 
west, not only in regard to its thickness and its geographical distribu- 
tion, but also in its influence on the agricultural capabilities of the 
country.” “In summing up the extent of country underlaid by this 
great formation, we find that south of the Lignite Basin, it occupies an 
area of two hundred miles in length, and one hundred in width; or, 
twenty thousand square miles, North of the Great Lignite Basin, 


