128 RECONNAISSANCE FROM CARROLL, MONTANA, 
out the scanty vegetation. Grass is hardly present at all, and even the few weeds have a hard 
struggle for existence. This is true for fifteen miles from the river. Approaching the hills, how- 
ever, the grass is more abundant; and occasionally in the more favored spots it is sufficiently thick 
to make it worth the while of citizens of Carroll to come here for hay. In addition to the small, 
smooth pebbles, the same masses of red and gray syenite found on the Crooked Creek road were 
seen here. The relations of these will be spoken of more particularly hereafter, (p. 135). The 
quartzite pebbles are most numerous within ten miles of the river-bank, and hardly extend much 
beyond twenty miles. The same is true of the blocks of crystalline rocks to some extent, though 
they were seen occasionally quite near to the Little Rockies. It is to be remarked that here also 
there are no deposits of drift, the pebbles being merely sprinkled over the surface. The nearer we 
approached the mountains, the more numerous became the slightly washed and rounded fragments 
of trachyte, containing large, clear crystals of orthoclase. Some fragments of the same rock, by the 
way, had been seen near Carroll, on the south side of the river. The source of these fragments was 
obviously to be found in the hills we were approaching, and subsequent exploration proved the 
truth of this conjecture. 
The old trail was left after a time, and we continued on our way, striking across the prairie 
toward the hills. The country was very dry and barren; the only water seen being in some holes, 
and that was intensely alkaline. In general, it may be stated here that these hills are very dry, 
and do not give rise to the numerous running streams, which make the region near the Judith 
Mountains atiractive. Thelevel character of the prairie was favorable to the progress of the ambu- 
lance, but_not at all so for geological investigation; an occasional wash of black shales being the 
sum-total of all that was observed during a march of twenty-five miles. As we approached the hills, 
we passed near to the edge of the high bluffs, which pitched steeply down to the valley of Little 
Rocky Mountain Creek. The view which was opened out to us was extended and striking, looking 
down on the Bad Lands of the creek at hand, and those which extended on indefinitely westward. 
The bed of the stream offered attractions for geological work; but the descent promised so badly 
for the mules and their load that it was decided to turn away, and keep on the high land. 
We made our camp in a meadow some two miles south of the mountains at a spot which fur- 
nished a little stagnant water. Here we had the hills in front of us, and on either hand a terrace 
about four miles apart, which stretched southward till they blended with the general level of the 
prairie. These high terraces two hundred feet above the level of the adjoining plain, are con- 
spicuous features of the landscape, and are important as bearing on the general question of the 
circumstances under which this country has been denuded. The results of the observations of the 
following day are contained for the most part in the accompanying sketch. We first examined the 
strata at the most easterly point (a). The intervening prairie was doubtless once covered with the 
upturned strata, but now only isolated patches are to be seen. Ata, we found a brown massive 
sandstone, cellular and remarkably honey combed on the surface as if worn by water washing 
against it. Its texture was even, with the exception of numerous rusty iron pellets. It dipped 
strongly (60°) southerly, strike north 80° east; and, standing up as a high wall or rampart, it had 
survived the denuding influences which bad been too severe for the overlying strata. The outer 
layer of this sandstone was 12 feet in thickness,and more compact than those that followed; the 
total thickness being 40 feet. The next exposure was in the coulée 400 yards behind this wall, 
where followed a series of blue and yellow shales 500 feet in thickness. These had the same direc. 
tion of strike as the sandstone, but the dip was steeper, becoming nearly vertical, then changing 
to north. The observations in this direction were cut off by the high hill of trachyte at b. The talus 
from this hill extends out for some distance from it, covering up all sedimentary strata beneath it. At 
¢ rises a second complementary hill of trachyte, and lying between these two and limiting the 
prairie in this direction is an imposing limestone wall. This is worth mentioning, for it is so con 
spicuous an object as to be distinctly visible in clear weather at a distance of fifty miles to the 
south. The mountains seem from such a point to have a continuous white girdle running around 
them. This is due to the limestone and to its continuation east and west in the range; the abrupt 
wall of trachyte also continues this girdle where the limestone is interrupted. The limestone 
wall shows no stratification, but its face has a steep dip south 70°, and, in character as well as in 
result of weathering, resembles the Carboniferous limestone so often described. 
