100 
This diversion of water was brought about by the location of the 
streams in question with respect to the rock structure of the region.’ The 
strike of the rocks is nearly north and south. ‘The lower rocks in the 
northeast and southeast part of the region are the soft, easily eroded 
“IKnobstones.” Salt creek, on account of its very large size, readily etched 
its lower course to grade and when the soft knobstone underneath the 
Mississippian limestone was reached it probably formed falls which rap- 
idly retreated headward and permitted proportionally early deepening of 
many of its tributaries. Throughout the central part of the region the 
heavy, resistant, Mississippian limestones form the country rock, dipping 
westward, through which no drainage channels completely penetrated. The 
headwaters of Indian creek lie upon these rocks and nowhere do they cut 
through them. In a large part of its course the soft shales, sandstones and 
thin limestones of the Mississippian formations form the upland rocks. 
The result is that Indian creek with long and gentle grade could not com- 
pete with Clear creek, a branch of Salt creek, in deepening the channels of 
its headwaters. In the west part of the region the soft formations of the 
upper Mississippian and the basal soft sandstone and soft shales of the 
Coal Measures or Pennsylvanian rocks form the upland. The Mitchell lime- 
stone forms the beds and basal part of the bluffs of the streams in this 
part of the quadrangle. Richland creek for the most part lies in these soft 
formations and flows a short distance to the west fork of White river at 
Bloomfield, reaching about the same elevation as Indian creek flowing twice 
the distance to the east fork of White river north of Shoals, in Martin 
County. Richland creek being thus favored soon reduced the valleys of 
fts headwaters below the level of Indian creek. his left the head of 
Indian creek 100 to 150 feet above the creeks on either side and its bed 
resting on soluble rocks. That is, Indian creek lay upon a table land of 
soluble rocks with lower streams on either side of it. The divide between 
Indian creek and Clear creek has been cut through and removed much of 
the way just southwest of Bloomingten. Thus the headwaters of Richland 
creek northeast of Stanford Station are at a level of GSO to 700 feet above 
tide and were cut into the top of the Mitchell limestone which dips west 
Trom the Indian creek plain into Richland creek valley, while a west branch 
of Indian creek lay at an elevation of SOO feet but a half-mile or a little 
more to the eastward. The divide between the two is formed of the shales 
* See geologic map accompanying 28th Ann. Rep. Ind. Dept. Geol. Nat. Res. 1904 
