104 KANSAS ACADEMY OF SCIENCE. 



FURTHER STUDIES IN THE MENTOR BEDS. 



By Alfeed W. Jones, Kansas Wesleyan University, Salina. 

 Read before the Academy, at Topeka, January 1, 1903. 



~1 /rY only apology for sticking- to this subject is that my geological 

 -^-^ field-work has been limited to the counties of Saline, Lincoln, 

 Ellsworth and McPherson during the past two years, and the fact 

 that the Mentor Beds are not receiving much attention from other 

 geologists. 



The Dakota and its associations in Kansas afford a most fascinat- 

 ing field for investigation, and demand a thorough and careful study 

 before many tangles can be unraveled. 



Although I am not prepared to attempt any plan of division, I am 

 inclined to believe that a very careful study of the Dakota would 

 separate it into different leaf -bearing beds of different groups of 

 plants interspersed with thin, shell-bearing layers. 



The division line between Comanche and Dakota appears to be 

 less distinctly marked as more light is thrown upon it. Three or four 

 years ago I thought I was quite certain regarding some features of 

 the Mentor ; to-day, after much more investigation, I know much less 

 about it. However, I am still inclined to believe that the "Mentor" 

 proper lies at the base of the Dakota ; that when thoroughly traced it 

 will reveal to us the outlines of an ancient gulf, with several of the 

 inlets marked by fossil beds containing only fresh- or brackish-water 

 species. 



I have now located three of these localities — one four miles north 

 of Salina, in the Claflin pasture ; one north of Brookville, on Mul- 

 berry creek ; one about six miles northeast of Kanopolis, Ellsworth 

 county, on the Smoky Hill river. 



The Marquette region, southwest of Marquette, reveals a puzzling 

 condition — in the bottoms of ravines we find Permian shales; resting 

 upon this the calcareous shales of the Kiowa ; then apparently typical 

 Dakota sandstone bearing fossil leaves; and above this a heavy ledge 

 of sandstone containing an abundance of Mentor fossils. 



Although I have not had the opportunity of exploring very far 

 southwest, I am informed that shell-bearing rocks outcrop at many 

 places in western McPherson and eastern Rice counties that I did not 

 visit. 



Several more cases have been reported to me of shell-bearing strata 

 having been found near the base of the Dakota in well-digging, and 

 a few more surface exposures have been found in vSaline county. 



