255 
ficient to entirely control the drainage. Thus it is noticeable that the 
water-shed between waters flowing east directly into the Ohio and those 
flowing southwest and reaching that stream after many miles is at the 
very eastern face of the plateau. In Floyd and Harrison counties it :s 
often no more than one or two miles from the Ohio. The streams flowing 
to the west have a gentle fall. following in the main the dip of the strata. 
The resulting topography is of the gentle rolling type common in many 
limestone regions. The streams flowing to the east, on the contrary, are 
short. and flow through deep, narrow gorges that have been cut down 
through the soft knob shales. These valleys are often from 250 to 300 feet 
deep. . 
THE UPPER LIMIT. 
The parting between the top of the Knobstone group and the overlying 
Carboniferous limestones crosses the Ohio River near the east side of 
township 6 south, 4 east. The line of parting in the extreme south is low 
in the hills and is covered by cliff debris and alluvium, consequently it 
cannot be continuously traced in going northward until township 4 south, 
5 east, is reached. 
From the point where it enters Indiana the upper limit of the group 
runs northward along the eastern face of the escarpment on the west side 
of the Onio, seldom extending more than two miles back from that stream. 
On account of its dip it is carried successively higher in the hills, reaching 
their very tops in township 2 south, 6 east. From here northward the 
base of the limestone is found at the tops of the hills. 
The line of parting from its southernmost exposure, runs northward in 
a very sinuous line through townships 6, 5, 4, 3 and 2 south, 5 and 6 east, 
until it reaches section 31, township 2 south, 6 east. At this point, which 
is four miles west of New Albany, the outcrop turns westward and follows 
along the south side of Indian Creek until it is carried beneath the drain- 
age level and crosses to the north of that stream in section 20, township 
2 south, 5 east. There are low dips showing a very low anticlinal fold in 
the southeastern part of 2 south, 4 east, and the southwestern part of 
m7 south, 5 east, and it may be to some extent due to this structural feature 
that Indian Creek and its tributaries have cut through the limestones, ex- 
posing the underlying Knobstone. through these townships. 
After crossing to the north side of Indian Creek the upper parting be- 
tween the Knobstone and limestone turns again and runs to the north- 
east in a yery sinuous line. It gets higher in the hills until it again 
