232 The American Geologist. October, iqob 
pod shells. This flint is the cap rock of many of 
the Arikaree buttes of the region adjoining the 
Oligocene outcrop 4 
2. Clayey, reddish brown sandy shale to massive 
sandstone breaking down in terraces in some 
places 25 
3. Unseen •. 60 
10. Section on Rattle Snake butte, four wiles south of the Butte 
Creek school house. 
Arikaree: Feet Inches 
1. Very hard, massive to thin-bedded sandstone, so 
firmly cemented with silica that the rock is a 
quartzyte. (The dip of these sandstone strata is 
toward the north ' . . . . 8 
2. Volcanic ash 10 
3. Hard, light brown, massive to thin-bedded, often 
laminated, cross-bedded sandstone (dip southeast) 140 
Oligocene (?): 
4. Unseen 100 
Pierre Shales : 
5. Unseen 40 
11. Section in the Bad Lands just across the river from the Ring- 
Thunder day school. Dip of strata uorth. 
Arikaree: Feet Inches 
1. Sand and sandy clay 40 
Oligocene: 
2. Light colored shale, weathering reddish on exposed 
surfaces, the reddish color being due to the par- 
ticles of iron scattered through it 40 
3. Light colored, occasionally greenish tinged, soft 
shales, banded with harder streaks of practically 
the same material, in which are occasional iron 
nodules. On weathering the whole series breaks 
down into light chocolate to pinkish and cream 
colored potato hills and cones, when isolated; 
and when joining a mesa, into smooth, symmet- 
rical hogbacks 50 
4. Same as three above except the shales have not the 
pinkish, greenish tinge in their color 45 
!>. Yellow, clayey shales, containing so many iron 
nodules that, at a distance, the exposure has a 
brownish to a red rust, red ochre color, due to 
the broken pieces of iron scattered over its face 10 
6. Unseen 10 
Pierre Shales: 
7. Grayish-black shales (Baculites) 10 
