The Comanchean of Central Kansas. 217 



any of either the Mentor beds or the underlying, the Dakota 

 resting- directly on the Permian. Such areas may have been 

 islands in the Comanchean sea-; the region may have been 

 near the northern shore of this sea, w^hich because of the 

 brief existence of Comanchean waters in central Kansas must 

 have been one of reentrants and salients, upon the latter of 

 which there could have been no deposition, so that now they 

 would project, tonguelike, into the fossiliferous areas; or the 

 Comanchean beds were eroded out before the deposition of the 

 subsequent Dakota. 



The last hypothesis raises the question as to the upper 

 surface of the Comanchean strata. Has this been eroded, or 

 are the Dakota beds continuous therewith? The writer is 

 aware of no evidence showing that erosion followed the depo- 

 sition of the marine sediments, and it appears highly prob- 

 able that the continental deposits of which the basal Dakota 

 is composed rests directly on the Comanchean strata. If this 

 view be correct, there is opened the question as to the upper 

 limit of the Comanchean. The writer is of the opinion that it 

 should not be drawn at the top of the Mentor beds, but should 

 include some of the beds which are called the Dakota, 



DETAILED DESCRIPTION OF THE COMANCHEAN STRATA. 



Kiowa Shales. The Kiowa shales of central Kansas have 

 exercised no marked influence in the development of sharp 

 features in the topography. Being thin and offering little 

 resistance to erosion, they weather readily and generally un- 

 derlie grass-covered slopes. The locality where they were seen 

 by the writer to best advantage is in Walnut township of 

 Saline county, three miles east and two miles south of Mentor, 

 where at an elevation of about 140 feet above the Smoky Hill 

 river there are exposures along the side of the road in fully a 

 dozen places of three to four feet of an oyster-shell limestone. 

 In places the rock is partly crystalline. Overlying the lime- 

 stone is an unfossiliferous red sandstone, while further down 

 the slope in the float were collected a few blocks of sandstone 

 containing Mentor fossils. In the road ditch below the lime- 

 stone are excellent exposures of laminated, shaly yellow sand- 

 stone. 



1' A supposition to the samp point wns made hy Professor Mudge (5, 6). 



