Thee : D 2. —eEeEeo7~—3O— — 
259 
was to work out the topography, not so much attention was paid to the 
geology, but in most places it was worked out with some degree of ac- 
curacy. 
This formation is made up of sandstones and shales. Above it is the 
Subcarboniferous limestone; below, the New Albany black shale. In the 
south the shale predominates; in the north, the sandstone. At the base 
of the formation is a layer of hard greenish-blue limestone, called the 
Rockford Goniatite limestone. This layer is very persistent and varies 
from ten inches to three feet in thickness. In the southern part of the 
State, north to where it is covered by a glacial clay, the eastern limit of 
this limestone is but a few feet below the general surface of the country, 
being covered by soil and clay to the depth of eight to twenty feet. 
None of the sandstone is pure. It is mixed with considerable quan- 
tities of muddy shale and also contains small quantities of iron, which is 
shown in the weathered rock. The shale is muddy, easily eroded, and con- 
tains large quantities of iron nodules. In most places there is a gradual] 
transition from the shale to the sandstone; just where one leaves off and 
the other begins it is difficult to tell. This is especially true in the south- 
ern part of the State. Farther north there are alternating beds of shale 
and sandstone, but the beds of shale are much the thinnest. 
The formation shows an entirely different topography in the south 
from that in the north. It makes up the knobs of Floyd, Clark, Scott, 
Washington and Jackson counties dnd the hills of Bartholomew, Brown 
and Morgan counties. 
In the south, in Floyd and Clark counties, the knobs present a bold 
face toward the east; they are steep and vary from 200 to 400 feet in 
height. Hast of the knobs the country is comparatively level and farther 
north outlying hills are found. These outliers in northern Jackson and in 
Bartholomew counties extend eastward from the main range of hills five 
or six miles. 
In the four cross-sections under discussion the dip of the rock was not 
determined, but it was measured in other places and found to be 26 
feet to the mile to the west. 
The southernmost of the four cross-sections was run in township 1 
-south, range 6 east, a short distance south of St. Joseph, a small town on 
the J.. M. & I. R. R., six miles north of New Albany. The Subcarbonifer- 
ous limestone is found on the top of the easternmost knob or hill and is 
250 feet above the Goniatite limestone to the east. This is about the 
