116 RECONNAISSANCE FROM CARROLL, MONTANA, 
mentioned. Those on Camas Creek are in thick, rather indistinct, layers, and contain more or 
less bluish sand in irregular layers, and sometimes a little coarse gravel. Traces of this deposit, 
containing what appear to be remains of Rhinoceros, were also observed two miles or more south of 
Moss Agate Springs (to be referred to later), and at a considerable elevation above the creek-bed. 
With more time than we had at command, they could, no doubt, have been traced much farther, 
although in many places the beds have been washed out, or have been covered by the later local 
drift. 
Tn the Miocene beds were found a species of Rhinoceros; several species of Oreodon, Leidy, and 
Eporeodon, Marsh; a canine tooth apparently of Hlotherium, Pomel; and remains of Turtles. In 
the Pliocene beds, the principal fossils were a species apparently of Merychyus, Leidy; remains of 
an equine smaller than the modern horse; and Pliocene Turtles. These fossils have not yet been 
carefully studied, and, for this reason, their relation to the remains found in the other lake-basins 
of similar age cannot here be stated. The line of separation between the Miocene and Pliocene 
beds is, in some places, well marked. It consists of about six feet of bard sands interstratified with 
layers of very small, water-worn pebbles, soldered together into a hard mass. Each of these layers 
is about 6 inches in thickness. Immediately above these strata, the Pliocene fossils were found. 
It is known that in the neighborhood of Fort Shaw, and near Helena, Pliocene deposits exist; 
and near Fort Ellis, and in the valley of the Yellowstone, we saw, but were unable to examine, 
gray sands and marls, which Dr. Hayden refers to the same age. No Miocene beds, however, have 
been identified at any of these localities. It seems probable that, in Pliocene time at least, the 
Baker Lake may have extended north to the Missouri River, and perhaps up that stream to the 
“Three Forks”, thus connecting with the lake which existed near Fort Ellis. Indeed, it would 
seem that we just touched upon the southern edge of this basin, which may have extended far to 
the north and west. 
An interesting point in connection with these deposits is the fact that, with the exception 
of one deposit in Colorado, they are at a much greater elevation than any other beds of the same 
age now known on the continent. The elevation of the White River beds is about 3,000 feet, and 
that of the Oregon basin somewhat less; while that of the deposits near Camp Baker is over 
5,000 feet. 
On the east side of the plain on which Camp Baker stands, the Miocene has entirely disap- 
peared. It is to be noticed that these Tertiary beds were deposited after the elevation of the older 
rocks, and that most of the denudation now visible in these rocks must have been accomplished 
before the deposit of the Tertiary, as it is repeatedly seen filling the depressions and unevennesses 
in the slates, as also covering over the ridges of trachyte. Underlying the Tertiary, and tilted 
up at a small angle, appear a series of yellow slates and shales, which are quite generally distrib- 
uted in this region, though not seen elsewhere. They are seen geverally as a fine-grained slaty 
rock, friable and weathering readily, so that exposures of the rock in place are rarely found. Ovca- 
sionally, there are observed in them immense black concretions of remarkable structure. In the 
interior, these consist mostly of a calcareous clay, very hard, and showing distinctly what is called 
the cone-in-cone structure. Outside of this, the lime is purer, though lying in concentric layers, 
and the exterior shell is made up of fibrous calcite half an inch in thickness. The clay cones 
radiate from the center of the concretions. 
The slates are destitute of fossils, and their age is only a matter for conjecture. The most 
remarkable feature connected with them is that they have, in spots, a bright brick-red color; 
thus, in riding over the country, a patch of intensely red-colored soil will be seen here and there, 
strongly suggestive of the burned lignite beds of the Missouri River. The slate has at such points 
the appearance of burned pottery; the material being harder and firmer than the surrounding rock. 
In some cases the red color was uniform in the rock; but generally it was distributed in successive 
bands, as though produced by the action of hot water. The red patches are quite local, and seldom 
cover more than a few square yards, though in one case they were seen extending along a range of 
hills for a hundred yards or more. That the effect produced has been caused by the action of heat 
cannot be questioned, though under what conditions no attempt is made to conjecture. As has 
been said, these shales and slates are tilted up unquestionably ; but their exact relations to the 
underlying rocks could not be made out without more opportunity for investigation than we had, 
* 
