114 B. N. A. BOUNDARY COMMISSION. 
in all stages, from those simply reddened, to others completely porcelain- 
ized, or fused into lava-like material. Some of the baked sandstones still 
retain obscure impressions .of plants. Overlying the red beds are 
whitish and yellowish arenaceous clays, of such light tints, as to appear, 
from a distance almost like chalk. 
The thickness of beds included between the highest and lowest 
exposures seen here, mast be from two to three hundred feet, and so far 
as comparison can be made, the section shows a remarkable general 
agreement with that of divisions a. and g. of the Bad Lands, 115 miles 
eastward. 
279. The valley of the East Fork of Milk River, where it crosses 
the Line, is wide and trough-like, with scarped banks about forty feet in 
height. The cliffs are composed entirely of drift deposits, and it 
maintains this character as far up and down as I have been able to 
examine it. Many fragments of Cretaceous fossils, and large masses 
of fossiliferous ironstone, are found in the bed of the stream, and in the 
clay banks; and so large a proportion of the drift is formed of the 
redistributed matter of the Cretaceous clay-shales, that it seems probable 
that they exist here at no very great depth. Baculites grandis is 
among the fossils, and was not elsewhere observed; there are also a 
' few species which are probably derived from the lower beds of the 
Tertiary. 
280. A most interesting section occurs in a deep valley about six 
miles west of Hast Fork. Exactly on the Boundary-line the banks show 
good exposures of the Cretaceous shales, more closely resembling in their 
lithological character those seen in the upper part of the Pembina 
Mountain sections, than those of the same beds as occurring in the 
vicinity of Wood Mountain. The rock is almost, or quite horizontal, 
is pretty hard, and well stratified, and includes white bands like those 
already referred to. On following the valley about a mile northward, 
these clay-shales seem to bend suddenly upward, and give place to 
a series of rocks, which appear to underlie them, and which differ from 
them altogether in character, and include massive layers of sandstone 
and thick arenaceous clays. 
281. A section was measured across the up-turned edges of these 
beds, which is given below, the measurements being reduced, so as to 
represent the actual thickness of the strata. The section—supposing no 
reversal to have taken place—is in descending order :— 

