GEOLOGICAL SCIENCES lSS Lithologic Basis for Correlation of Mississippian Rocks in the

In the past subsurface rocks of Mississippian age throughout north central Oklahoma have generally been considered as a single unit and referred to as undifferentiated Meramec-Osage in age. This paper is a summary of two Master of Science theses recently completed at the Uni-versity of Oklahoma by the writer and Wayne D. Thornton, in which an attempt was made to subdivide the Mississippian system in north central Oklahoma on the basis of lithology. North central Oklahoma as described for the purpose of this paper includes Alfalfa, Garfield and parts of Woods, and Grant Counties. All descriptions of lithology were obtained from the microscopic exami-nation of well cuttings. Lithologic descriptions of time-rock units assigned to the Mississippian system in Kansas by Clair (1948) and Lee (1940) were used as the criterion for the subdivisions proposed in this paper. Joseph R. Clair (1948) subdivided the Mississippian system into its four series, in descending order, the Chesterian, Meramecian, Osagean an