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the country to the south, it must also nearly mark the line which . 
_ place bounds the southern margin of Tertiary. . ‘ee * 
319. Two branches of the Milk River cross the Line with north 
easterly courses between the Buttes and the Rocky Mountains, and 4 
uniting to form the main stream of the Milk River, flow eastward, nor 
of the Buttes, and recross the forty-ninth parallel, with a south-easte “i 
course, as has been already mentioned. The Line crosses the eres of Rad 
these tributaries, at the 696 mile point, and though the stream flows pas 4 
a deep valley, the banks do not show anything but drift. Six miles — : 
west, however, a bend of the river again approaches the Line from the 
south, and it here exhibits very interesting sections of rocks probably — 
belonging to the base of the Lignite Tertiary. | ‘a “x 
320. The best exposures are found in a group of small hills, which — a) “a 
assumes in miniature, the appearance of the Bad Lands, and stands like © 
an island of older rocks among the drift deposits, which lap around its ne ae 
base. It is an outlyer of a plateau, which, with irregular edge, runs — 
northward with a little easting, where it crosses the Line. The beds are | = | 
horizontal, and are exposed for a thickness of about sixty feet. The is 
lower portion of the section is of pale greenish-grey clays, while above, — ae " 
the greenish colour is not so marked, and there are somewhat massive = 
sandstones. In some places the latter are almost conglomerates, and 
hold many small pebbles, the majority of which are of greenish shale. — 
They also include fragments of reptilian bones and large Unio shells. | 
Small nodules occur abundantly in some layers of the lower greenish ~ 
clays of a tint similar to the matrix. The bones are found in consider- 
able abundance in all parts of the section, but are much crushed and ; 
fissured. When imbedded in the bank, they are purplish-black in 
colour, but on weathering, assume whitish and rusty tints. It is very teu 
difficult to dig the bones out of the bank itself, from the great hardness 
of the dry clay relatively to that of the fossils, and where washed out by — 
the rains, they are found only as broken fragments, difficult to recon- — . 
struct. From specimens obtained here, however, in the course of a few 
hours, Prof. Cope finds, besides many broken bones of dinosaurs, new “A 
species of Cionodon and Compsemys, which he has called C. stenopsis and 
C. agmius, respectively. 
321. The greenish clay beds are doubtless formed of the disinteg- a 
rated material of beds of green shale, similar to those represented by the a “a0 
pebbles in the conglomerates. A microscopic examination of the clay ze tiny 
did not reveal any recognisable fragments of green mineral or rock, the — a i 
shit, a 

