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. colour apparently residing in the very fine argillaceous matter, through 
which a few large partly rounded grains of transparent quartz are 
-_ seattered. The bones, in the manner of their preservation, much 
resemble those of division 8. of the Bad Lands south of Wood Mountain, 
which these beds may possibly represent. The lithological character, 
however, has changed considerably, as compared with any of the more 
~ eastern exposures of the Tertiary, though connecting links are supplied 
by the sections on the main stream of the Milk River, and in the vicinity 
of the Buttes. Sandstones are now more important, and coarser in 
F texture, and the clays and argillaceous sands have assumed more defi- 
: nitely than ever before, the greenish tint above referred to. 
| 322. It is a curious coincidence that near this place, also, green 
5, slaty shale begins to be an abundant constituent of the drift. It does not 
Re: appear to be derived from the degradation of the Tertiary rocks, as the 
, matrix of their conglomerates is generally harder than the enclosed 
shale, but must come directly from the slopes of the Rocky Mountains, and 
increases in abundance on approaching them. It would thus appear 
probable that even in early Tertiary times some part at least of the 
mountains was sufficiently elevated to allow a distribution of fragmental 
material similar to that afterwards taking place on a larger scale in the 
glacial period. ; 
323. About fourteen miles further west, the Second Branch of Milk 
River is met with, and in its valley, for several miles, beds resembling 

























those last described are exposed and are still apparently quite horizontal. 
BS The best sections—which are near the river level—probably show beds 
somewhat lower in the series than those last described, which the higher 
parts of the banks on both sides of the valley more closely resemble. 
About forty feet above the level of the stream, a thin band of nodular and 
ferruginous limestone was found to be highly fossiliferous. The rock 
is dark bluish-black internally, but weathers reddish-brown. Frag- 
ments from the same, or a precisely similar band, were previously found 
detached in the valley of the First Branch of Milk River, twenty miles 
eastward. The fossils are entirely those of fresh-water, and include 
specimens of Paludina, Limnea, Planorbis, Spherium, and a Bulinus or 
Physa. The Planorbis is almost certainly that called P. subumbilicatus 
by Meek, from the Tertiary of Fort Clarke, ( Valvata subumbilicata of 
Smithsonian Check List?) though I have not had an opportunity of 
comparing it with authentic specimens. It also, however, appears to 
be indistinguishable from small specimens of Planorbis parvus of Say, now 
‘ ‘2 CRETACEOUS AND TERTIARY—BRANCHES OF MILK RIVER. 131 

