180 J F. NEWSOM 
are left out of the discussion, as are also those streams that flow 
across the productive Coal Measures west of West White River. 
SUMMARY. 
In summing up the discussion of the drainage systems of 
southern Indiana attention is called to the following points : 
1. The drainage in the region but thinly covered with drift, 
as well as in the driftless region, is controlled by the geologic 
structure. 
The drainage (except in the eastern area) is toward the 
southwest, with the dip of the strata, and is such as would logic- 
ally develop from a gradual elevation of a land surface, beginning 
at the east part of the state, and a corresponding recession of 
the water toward the southwest. The evidence points to the 
conclusion that the present drainage has developed from such 
an ancient initial drainage, and the writer believes this to have 
peen the case. 
2. The writer is unacquainted with any evidence in southern 
Indiana that the drainage has ever been toward the north and 
Castes 
From above Madison to the southwestern corner of the state the 
Ohio River cuts more or less directly across successive groups of 
hard and soft strata. This is the position that would have been 
occupied by the stream had its course been developed across the 
groups of strata in question as those strata were gradually raised 
above the water at the west side of the land mass formed by the 
Cincinnati Arch, and a corresponding retreat of the water to the 
west. It is believed that the present course of the Ohio from 
and below the neighborhood of Madison has been developed 
from such ancient initial drainage—with many periods of com- 
parative rest, and of activity, of course, corresponding with 
depressions and elevations of the land surface of the region 
traversed. 
tSee GERARD FowWKE, “Preglacial Drainage Conditions in the Vicinity of Cincin- 
nati,” Zhe Ohio State Academy of Sciences Special Papers, No. 3, p. 68 e¢ seg. Evi- 
dence is produced to show that the Ohio flowed northeastward in preglacial time, from 
near Madison. 
