112 RECONNAISSANCE FROM CARROLL, MONTANA, 
part of this is yellow and quite ferruginous; that below whitish and a little shaly. It varies some- 
what at different points; in one place turning into a soft, dark-colored slate in very thin layers. 
The whole exposure may be 15 or 20 feet in thickness; the sandstone having a very slight south- 
easterly dip. No fossils could be found, and the rock seemed to be without any special character- 
istic features, with the exception of pipe-stem pieces of carbonate of lime, which were quite common. 
They occupied a vertical position, sometimes curving more or less, and were 6 to 15 inches in 
length; possibly they were holes in the sand made by borers and subsequently filled up. 
West of Hopley’s Hole, the plain is nearly level for a long distance, broken only by one or two 
gullies. The general slope of the whole is very gradual to the south toward the Musselshell River 
and far beyond. In this direction, there is nothing to break the view, and the eye wanders unre- 
lieved over a vast range of dry, parched prairie, from which, at midday, the heated vapors arise, 
producing the illusive phenomena of the mirage. 
Haymaker’s Creek, twenty-five miles from the gap, offers another example of the extensive 
erosion which has taken place in this region. The stream at present carries very little water, and 
that quite strongly alkaline, especially late in the summer, at which time it barely moves at all. 
On the west side, the terrace is high and distinctly marked. It may be traced from the mountains 
to the Musselshell River with the same gradual slope noticed elsewhere; here also quite inde- 
pendent of the dip of the strata, which make a small angle with its upper surface. On the east 
side, the slope is very gradual; the final height not being attained for several miles. 
A short distance below the road-crossing, the sandstone is exposed. For the most part, it is 
a fine-grained rock of even texture, and of a light-bluish color, becoming yellow on exposure to the 
weather. Much of this lies in exceedingly thin, paper-like layers. There are also a few layers of 
a blue, impure limestone, and toward the top a bed of coarse sandstone, almost a conglomerate, 
containing some indistinct plant-remains, shells, and a few sharks’ teeth and vertebra, which show 
the beds to be Cretaceous No.5. The remains are too poorly preserved to be specifically identified. 
The genera are as follows: 
1. Grypheea, sp. 
2. Ostrea, sp. 
3. Lamna, sp. (teeth). 
4, Galeocerdo, sp. (teeth). 
The strata have a slight dip (5°) northerly; and a little to the north, where the thin-bedded 
sandstone only is visible, the beds are horizontal or dip slightly to the south. A mile or two far- 
ther, «4. ¢., west, we meet several outcrops of a dark ocher-yellow sandstone, in which some pipe- 
stem calcareous fragments suggested those found at Hopley’s Hole. A few indistinct vegetable 
remains were also obtained, but nothing characteristic. The slight dip is reversed in a subsequent 
exposure, showing an extremely low fold, the meaning of which will be explained later. Fol- 
lowing these are a series of bluffs, sandstones, or sandy shales, some of which we were enabled to 
visit. None of them afforded us any fossils. Over these, we noticed a few washed exposures of 
white and cream-colored clays. 
These doubtless all belong to the Upper Cretaceous, though, in view of their very slight dip, it 
would require more time than we had at our disposal to make out their exact stratigraphical rela- 
tions. In general, it may be said of these sandstone bluffs that they are more tilted as we approach 
the mountains, and seem to owe their position to the forces which threw up this range of hills. 
On reaching the Forks of the Musselshell, we come into a more attractive region. From the 
Judith Gap to this point, the prairie is almost a desert, dry and parched, and the grass very thin- 
Both branches of the Musselshell River, however, are fine running streams, and at their union the 
aliuvial country is wide and susceptible of profitable cultivation. Just before reaching the Forks, 
we passed a ranch where a system of irrigation had produced excellent agricultural results. 
From the Forks our road took us along the north branch of the Musselshell River, and two 
miles beyond we entered the Musselshell Cation. The open country here is rough, and is charac- 
terized by many step-like ridges of sandstone, on one side steep, showing the edges of the strata, 
and on the other sloping off gradually, and covered over with grass. 
