102 
RECONNAISSANCE FROM CARROLL, MONTANA, 
concretion. It is to be noticed that these fossils, as a rule, are not clustered together in the center 
of the concretion, but lie in a single layer; and it is not uncommon to see this layer continued in 
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Course from Carroll to Box Elder Creek S. 55° W.; 
Profile Section from Carroll to Cone Butte, Judith Mountains. 
Jrom Box Elder Creek to Cone Butte S. 30° W. Distance direst ebout 40 miles. 
line from one concretion to the others lying immediately adjoining 
it. This fact indicates the relation in point of time between the 
deposit of the shells and the formation of the concretions. 
The most common fossil in this association, and one which is 
met with almost everywhere on the prairie, is the Baculites ovatus, 
Say. These remains are often called “fossil fish”, “fossil ferns”, 
&e., by the white inhabitants of that section of the Territory; and, as 
they are so well known and so often spoken of, it may not be amiss 
to make aremark in regard to them for the benefit of the unscientific. 
They are not fish-skeletons, but are simply the shell of an animal 
somewhat allied to the present Nautilus, but having the shell straight 
and tapering instead of curved in a spiral. The delicate lines on 
the shell show the divisional walls, or septa, of the successive cham- 
bers in the shell. 
During a delay of a day at Crocked Creek, we were enabled to 
follow along the dry bed of the stream for several miles. This bed 
is filled with alluvial deposits of the black clay deposited by the 
stream, and through which it has again washed out its path, leaving 
steep walls three feet or more in height. The banks on either side 
show evidence of having been washed over, looking white, and a little 
sandy, and with the drift-pebbles collected in large numbers. Here 
and there the Cretaceous clays are exposed in high bluffs on either 
side of the creek-valley. These bluffs have sometimes a height of 
50 to 75 feet above the stream-bed. The clays are not to be dis- 
tinguished from those forming the immediate banks of the Missouri. 
They are blue-black or slate-colored, shaly, the layers being very 
distinct and everywhere characterized by the concretions. The 
layers of the clay are pretty uniformly horizontal, though an occa- 
sional slight dip is to be observed. At one point, we noticed a very 
low synclinal fold followed by a fault; the strata being displaced 
some 15 or 20 feet. This and other similar disturbances observed in 
this neighborhood we decided were undoubtedly local, being due to 
slips in the loosely-laminated clays, through the influence of run- 
ning waters. Many similar disturbances were observed along the 
river which were obviously due to a similar cause (see p. 125). 
From Crooked Creek, the road runs on nearly southwest, rising 
slightly till a point some few miles from Box Elder Creek is reached, 
when there is a more sudden rise of 50 feet up to a plateau, which 
on top, is very level, and the northern edge of which can be dis- 
tinctly seen extending some distance in both directions. 
The following cut (fig. 4) gives an ideal section * from Cone Butte 
to the Missouri along the line of the road, as obtained from measure- 
ments made by an aneroid. Itis to be observed that the line runs 
obliquely, making the distance somewhat farther than in a direct 
line, as will be seen by reference to the map. 
The highest point at which the undisturbed Fort Pierre Group 
was observed was 1,060 feet above the river; and deposits of this 
age were seen at various points along the Helena road until Camp 
Lewis was reached. The last point at which they were noticed was 
near the crossing of Warm Spring Creek, south of the Moccasin Mountains. 
*The vertical distances are increased nino times to admit of being brought within the limits of the page. 
The 
horizontal scale is (as on the map) 6 miles to tho inch; tho vertical scalo is $ mile (3,520 fect) to the inch. 
