542 A. C. PEALE 
High School, whose familiarity with Fergus County, Mont., was 
of the greatest assistance in the work. Knowing from the work 
of Stanton and Hatcher that the area north of the Missouri 
River and around the Bearpaw Mountains was one complica- 
ted in its geological structure by numerous faults and folds and 
areas of intrusive rocks, it was decided to begin the section far 
enough south so that if possible there might be no chance of 
error due to the occurrence of folding or faulting. We therefore 
followed the road leading a little west of north from Lewistown 
between the North and South Moccasin mountains to Deerfield, 
from which point we turned westward, reaching the Judith River 
about 40 miles above its mouth. This part of our course led us 
over the shales of the Colorado, as mapped by Calvert," with a few 
outcrops of the underlying Kootenai formation showing on either 
side of the lower slopes of the Moccasins. The Colorado shales 
are well shown at Stough’s ranch, having a thickness of about 1,000 
feet overlaid by a sandstone referred to the Eagle. This is a 
massive white sandstone not over too feet in thickness in most 
places. As followed laterally it fades out into a yellowish sand- 
-stone which is somewhat shaly. This sandstone caps the bluffs 
on either side of Judith River, contrasting strongly with the under- 
lying dark shales of the Colorado. Above it is an alternating series 
of massive yellowish sandstone and shaly beds reaching a total 
thickness of about 200 feet. A coal mine is worked in these upper 
sandstones about 2 or 3 miles east of the valley of the Judith River. 
Above these supposed Eagle sandstones the beds are soiter 
sandstones broken down and mainly covered. They are several 
hundred feet in thickness and undoubtedly represent the Belly 
River interval, but the outcrops were too meager to determine 
much in detail about them. 
The dark-colored shales of the Pierre resting on these sand- 
stones form the surface of the bench beginning several miles to the 
eastward of the coal mine, and the road to Kendall passes over 
them, several good outcrops showing, especially to the north of the 
road, but they do not show on the Judith south of the mouth of 
Warm Spring Creek. However, the Pierre shales appear in the 
t “Geology of Lewistown Coal Field,” Bull. U.S. Geol. Surv. No. 390, map. 
