230 Unwersity of Kansas Geological Survey. 
Water was found in this well but it was rendered brackish by con- 
tact with the shale. Another well pierced the Fort Pierre shales to a 
depth of nearly 200 feet. On passing from St. Francis towards the 
northwest we find the surface rising at first rather abruptly for 150 
feet, then gradually to 250 feet above St. Francis. This difference 
in altitude is occupied by the Tertiary formation and the wells 
measure its thickness, for the sheet water flows over the surface of 
the Fort Pierre shales. At a distance of fifteen miles from St. 
Krancis, on Hackberry creek, there is an abrupt descent of nearly 
300 feet. Along the bank of this creek are numerous outcrops of Ft. 
Pierre shale. These shales are of a rusty yellow color and contain 
Inecina occidentalis. Here again the surface of these shales seems 
to present unevenness. Forin several different sections of land the 
shales extend above the water level so that no water has been 
cbtained. Six or eight miles to the northwest of the Hackberry, on 
one of the tributaries of the Arickaree, is a mound of shale upon 
which rests a single pinnacle of Tertiary grit rock. This mound has 
received the name “Chimney Rock.” Similar mounds are called the 
“Barracks,” “Devil’s Cap” and “Fortification Hill.” The shales of 
these mounds contain Avicula fibrosa, Inoceramus crisp, and Bacu- 
lites ovatus, besides forms of Ostrea, Corbula, and Scaphites. The 
shales are of a brownish yellow color and contain rusty colored 
argillaceous nodules. 
Devil’s Cation, which is a southern tributary of the Arickaree, 
descends by almost perpendicular banks a distance of 100 feet, the 
major part of which distance is occupied by the Ft. Pierre shales. 
The shales vary in color from a light yellow to black and the charac- 
teristic fossil is Baculites ovatus. The record of a few outcrops will 
serve to show the relative position of the Tertiary and Ft. Pierre 
strata. 
Kast Cafion Section, numbering from the bottom: 
4th, Plains marl, 6 feet (top). 
od, Mortar beds, 20 feet. 
2d, Sand, 2 feet. | 
Ist, Shales, 40 feet, Baculites ovatus, (bottom). 
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