32 
IOWA ACADEMY OP SCIENCES. 
no bad smell and was not of the same quality as the water 
found in the forest bed. 
The next sample was taken at a depth of 220 feet. This is 
pure limestone with calcareous shale. The formation extends 
to 240 feet where it passes into dark shale and impure limestone. 
The sample contains a considerable quantity of iron and is very 
arenaceous. In it were found numerous small crystals of 
gypsum, which had evidently crystalized out of the material 
after it had been placed in the bottle. It probably resulted 
from the decomposition of iron sulphide, and the consequent 
action of sulphuric acid on the limestone. 
At 270 feet there was found a coarse, impure, hard limestone, 
dark in color. This resembles the brecciated base of the Saint 
Louis, and is probably referable to that horizon. 
The next sample, considered to be the upper portion of the 
Augusta, shows argillaceous shale with numerous pieces of 
fine-grained limestone. This formation still continued at 365 
feet, becoming somewhat lighter in color. At 400 feet, how- 
ever, dark, calcareous shale was found which contained a large 
amount of iron and silica. This was succeeded by blue, cal- 
careous shale, intermixed with small pieces of soft limestone. 
Twenty feet below, this merged into fine-grained, calcareous 
shale which, at 440 feet, passed into darker shale. Following 
this was light, soft, fine-grained shale. This is probably very 
near the base of the Augusta, making this formation a little over 
200 feet in thickness. No distinguishing characteristics can be 
discovered in the two adjoining samples, one of which is referred 
to the Augusta, the other to the Kinderhook. In the well at 
Sigourney the base of the Augusta was found at 365 feet. Since 
in this well the level of the top of the Saint Louis is 200 feet 
lower than it is in the one at Grinnell, it would seem that the 
base of the Augusta would here be at nearly 420 feet, the exact 
thickness being dependent upon variations in the thickness of 
the strata. 
If this conjecture is correct the uppermost member of the 
Kinderhook is represented by twenty feet of light, hard, brittle 
shale at 530 feet, which in turn passes into dark calcareous 
shale at 550 feet. The latter continued for twenty feet when 
limestone was found to occur again. It is fine-grained and asso- 
ciated with light, calcareous shale. There is little probability 
that this and the succeeding strata are entirely limestone, but 
are limestone and shale alternating, with, perhaps, considerable 
