100 



This diversion of ^Yatei' -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 horth and south. The io^Yer rocks in the 

 northeast and southeast part of the region are the soft, easily eroded 

 "Knobstones." Salt creek, on account of its very large size, readily etched 

 its lovper course to grade and when the soft kuobstone underneath the 

 Mississippian limestone was reached it probably formed falls which rap- 

 idly retreated headward and permitted proportionally early deepening of 

 many of its tributaiies. 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 Penusylvanian 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. This 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 Bloomington. Thus the headwaters of Richland 

 creek northeast of Stanford Station are at a level of OSO to 700 feet above 

 tide and were cut into the top of the Mitchell limestone which dips west 

 from the Indian creek plain into Richland creek valley, while a west branch 

 of Indian creek lay at an elevation of SCO feet but a half-mile or a little 

 more to the eastward. The divide between tlie two is formed of tlie shales 



^ See geologic map accompanying 2Stli Ann. Rep. Ind. Dcpt. Geol. Nat. Res. 1004 



