126 RECONNAISSANCE FROM CARROLL, MONTANA, 
and fill up the tunnel. It is to these causes, and to these alone, that the apparent irregularity in 
the strata at this point is owing, and not to any uplifting of the various mountain-ranges which 
exist in the vicinity. The beds at the mouth of the Judith have been very little, if at all, disturbed 
by this latter agency. 
The Fort Pierre beds form what may be termed the lowest bench of the bluffs along the Judith 
near its mouth. They have been very much denuded; at one point reaching a height of 560 feet 
above the river’s level, and at other places along the bluffs being apparently wanting. Deposits of 
this age are found, not only in the main valley of the Judith, but in many little ravines back in the 
bluffs as well. It is evident that they at some points have been covered by the younger rocks 
which have dropped down from above. From the facts above mentioned it is very difficult,-if 
not quite impossible, to get at the lowermost strata of the bluffs; and we were unable to accomplish 
it satisfactorily at any point. 
A considerable amount of surface-drift was noticed in the valley of the Judith and in the 
ravines running into it. This consists almost wholly of water-worn limestone pebbles, similar in 
appearance to the limestone observed at the western end of the Judith Mountains, in the Snowy 
Mountains, &c. One of these drift-pebbles contained Spirifera centronata, Winch. 
About two miles below our camp, and just above the crossing of the Judith, the Fort Pierre 
beds extend up the foot of the bluffs to a height of about 100 feet. Above these, where the main 
bluffs become visible, we noted 40 feet of soft, washed, yellowish clays, and over these 18 inches 
of hard, blue to gray, impure limestone, containing : 
1. Pholadomya subventricosa, M. & H. 
2. Liopistha (Cymella) undata, M. & H. 
3. Thracia Grinnelli, Whitf. (n. sp.) 
This was followed by 15 inches of soft, finely laminated sandstone, in color from white to 
yellowish-brown ; next came 20 feet of soft yellow clays; and finally a layer of sandy limestone 
from 3 to 6 inches in thickness, and consisting almost wholly of the following shells, crowded 
closely together : 
. Tellina scitula, M. & TH. 
1 
2. Spheriola Moreauensis, M. & MH. 
3. (2) Callista Deweyi, M. & II. 
. Lunatia concinna, H. & M. 
5. Narica crassa, Whitf. (n. sp.) 
6. Baculites ovatus, Say. 
At a point said to be about one-third of the way up the bluffs on Dog River, the following 
fossils were collected by two members of the party: " 
1. Mactra warreniana, M. & FH. 
2. Cardium speciosum, M. & H. 
3. Tellina (Arcopagia) Utahensis, M. & H. 
4, Tellina (Arcopagia) subulata, M. & H. 
They are imbedded in a soft yellow sandstone. These fossils, most of which are characteristic, 
and which have been compared by Mr. Whitfield with typical fossils now in the Smithsonian 
Museum at Washington, indicate the lower portion at least of these beds to belong to Cretaceous 
No. 5. 
At a point a little south of where the road descends into the valley, and about 300 feet above 
the level of the river, the following section was taken, from below upward : 
is 
Feet. 
Hard, gray, laminated sandstone, passing near the top into a softer, yellowish 
TOCK ..---5--2-00- + Nebemetras ogee ae Se RSS witianas a: Meant Ne cana en ata Sets 50 
Yellow clayey sands .... 0. 0-6... cece cece cee ee cee cece cent eet eet noes 30 
Soft yellow clays .-.....-.--.------ peti lactis Dion ce ea spet Rieke t iar esas heme ieach g 50 
PO GAL frccstb cate ais Lielee lane exe wie on cle tuc 4S ERED eM SEN ae tee os Peale See eee 130 
Where the road comes into the valley, a bed of hard white sandstone, interstratified with 
