Geological Observations. — Reagan. 233 
Total thickness of Oligocene here 155 
Total thickness of section 215 
12. Section irom the mouth of White Thnnder creek to the top of 
Mastodon buttes ( Three Points) at the head of Oak creek, one mile east 
of the artesian well. 
Arikaree: Feet Inches 
.1. Very hard, calcereous-cemented sand rock, in which 
are sticks, bones of birds, fishes, and animals, 
and fragments of turtle shell, cork-screw fossils, 
masses of fibers and rootlets, etc. This stratum 
is massive, and is the topmost rock of a great 
part of the Arikaree formation of the region. It 
is the Daimonelix beds of the Nebraska geolo- 
gists, so named on account of the fossil cork- 
screws (Daimonelix) found in it 8 
2. Partly lithified sand, having the appearance of dune 
origin (camel, horse, birds, turtles) 10 
3. Partly lithified sand of stream origin. The water 
sorting, laminating, and cross-bedding are all in 
evidence, (mastodon, horse, camel, etc.)* 8 
4. Partly lithified sand 40 
Oligocene: 
5. Light colored to pinkish shales (estimated) 234 
Pierre Shales: 
G. Dark gray shales (estimated) 400 
Total 700 
13 Section from the bridge northeast of Rosebud to the top of the 
hill in the cut on the Rosebud Boarding school wagon-road. Altitude 
estimated. 
Ogallala(?): 
1. "Mortar beds" of grit and calcarceous magnesian 
limestone permiscuously mixed 20 
Arikaree : . 
2. Partly lithified ash gray to brown sand 60 
3. Buff colored sand forming a perpendicular bank on 
the Rosebud side of the stream 60 
Total 140 
Formations in Detail 
The Pierre Shales of the Cretaceous system underlie 
the Tertiary formations wherever found and are the country 
rock in all places where the Tertiary has been removed by 
* The writci- sent the University of Indiana twenty-nine boxes of fos- 
sils from this locality. 
