| 
| Unit No. | 
Description | 
Thickness | 
 
| 
 
 | 
Ogallala
 | 
 
 | 
 
| 
30
 | 
Chalk - yellow
 | 
6 ft.
 | 
 
| 
29
 | 
Bentonite
 | 
0.05 ft.
 | 
 
| 
28
 | 
Chalk - yellow
 | 
5.4 ft.
 | 
 
| 
27
 | 
Bentonite
 | 
0.05 ft.
 | 
 
| 
26
 | 
Chalk - yellow, platy near top
 | 
16.1 ft.
 | 
 
| 
25
 | 
Limonite
 | 
0.1 ft.
 | 
 
| 
24
 | 
Chalk - yellow, (chalk becomes punky and more yellow, less silty)
 | 
12.4 ft.
 | 
 
| 
23
 | 
Chalk - yellow
 | 
6.8 ft.
 | 
 
| 
22
 | 
Bentonite
 | 
0.05 ft.
 | 
 
| 
21
 | 
Chalk - yellow
 | 
2.3 ft.
 | 
 
| 
20
 | 
Bentonite
 | 
0.05 ft.
 | 
 
| 
19
 | 
Chalk - yellow
 | 
0.65 ft.
 | 
 
| 
18
 | 
Bentonite
 | 
0.05 ft.
 | 
 
| 
17
 | 
Chalk - yellow, harder
 | 
1.15 ft.
 | 
 
| 
16
 | 
Bentonite
 | 
0.05 ft.
 | 
 
| 
15
 | 
Chalk - yellow
 | 
2.5 ft.
 | 
 
| 
14
 | 
Chalk - yellow to grayish
 | 
1.4 ft.
 | 
 
| 
13
 | 
Limonite and bentonite
 | 
0.2 ft.
 | 
 
| 
12
 | 
Chalk - gray
 | 
2.5 ft.
 | 
 
| 
11
 | 
Gypsum and limonite
 | 
0.1 ft.
 | 
 
| 
10
 | 
Chalk - gray
 | 
3.4 ft.
 | 
 
| 
9
 | 
Gypsum
 | 
0.1 ft.
 | 
 
| 
8
 | 
Chalk - gray
 | 
1.2 ft.
 | 
 
| 
7
 | 
Gypsum
 | 
0.1 ft.
 | 
 
| 
6
 | 
Chalk - gray
 | 
2 ft.
 | 
 
| 
5
 | 
Resistant ledge - shale?
 | 
0.2 ft.
 | 
 
| 
4
 | 
Chalk - gray
 | 
3.3 ft.
 | 
 
| 
3
 | 
Bentonite and gypsum
 | 
0.1 ft.
 | 
 
| 
2
 | 
Chalk - gray
 | 
5.7 ft.
 | 
 
| 
1
 | 
Bentonite and limonite
 | 
0.1 ft.
 | 
 
| 
 
 | 
Base of Castle Rock Section
 | 
 
 | 
 
 
 |