464 INDEX TO THE STRATIGEAPHY OF NORTH AMERICA. 



the rocks of the group as exposed in the region south of the Canadian River reach a thickness 

 of approximately 1,200 feet. 



SAPTJLPA GROUP. 



Area. — The rocks which constitute the Sapulpa group include everything from the base 

 of the Lenapah limestone to the base of the Pawhuska formation (as that term was used by 

 J. P. Smith) as these formations are exposed in the northern part of the State. Neither the 

 Lenapah nor the Pawhuska has been definitely located south of the North Canadian River 

 and for that reason the southern limits of the group can not now be accurately demarked. 



The area included in the group averages 35 miles in width, extending from the Kansas 

 line south to the vicinity of the Arbuckle Mountains. It includes all or part of Nowata, Wash- 

 ington, Osage, Pawnee, Creek, Tulsa, Okmulgee, Payne, Lincoln, Okfuskee, Pottawatomie, 

 Seminole, Pontotoc, and probably McClain, Garvin, and Murray counties. 



Stratigraphy. — Included in the Sapulpa group in Oklahoma are rocks which in Kansas 

 have been described under the following formation names: Coffeyville hmestone, Pleasanton 

 shales, Bethany Falls hmestone, Ladore shales. Mound Valley limestone, Galesburg shales, 

 Dennis hmestone, Cherryvale shales. Drum hmestone, Chanute shales, lola Hmestone, Lane 

 shales, Stanton limestone, LeRoy shales, Kickapoo limestone, Lawrence shales. Oread hmestone, 

 Kanwaka shales. 



The approximate combined thickness of these rocks as exposed in southern Kansas is 1,000 

 feet. In Oklahoma the thickness of the group gradually increases until at the Arkansas River 

 it is probably 1,200 feet or more. 



So far as known, with the exception of the Lenapah, none of the hmestone ledges exposed 

 in Kansas persist as far south as the Arkansas River. The Drum limestone sphts near the 

 Kansas line, and the lower member, which Ohern calls the Hogshocter, disappears some 20 

 miles north of Tulsa. The upper member of the Drum disappears soon after crossing the 

 State line. Two limestone lentils, the Dewey and Avant, come in not far from Bartlesville 

 and persist beyond the Arkansas River, where they also disappear. As the limestones disappear 

 near the Kansas line, sandstones become prominent and farther south increase in thickness 

 until they make up a considerable part of the rocks of the group, although, as in other parts 

 of the general region occupied by Pennsylvanian deposits, shales are the predominatiag rock. 



No accurate section has ever been made across the southern part of the region occupied 

 by rocks of the Sapulpa group, and for that reason it is impossible to do more than to approxi- 

 mate the thickness of the group along the Canadian River, but it is probable that in this region 

 it is somewhere between 1,500 and 2,000 feet. 



In its southwestern extension the Sapulpa group passes into and includes the eastern part 

 of the Oklahoma Red beds, being part of the so-called Chandler beds. * * * 



K ALSTON GROTTP. 



Area. — The Ralston group includes the rocks in the upper part of the Pennsylvanian series, 

 beginning at the base of the Pawhuska formation and extending to the base of the Wreford 

 limestone and its southern continuation, the Payne sandstone, which has usually been con- 

 sidered the base of the Permian." The group is exposed as a band averaging 30 miles in width 

 extending parallel to the other groups described in this paper, from the Kansas hne south toward 

 the Arbuckle Mountains. 



Neither the Pawhuska formation nor the Payne sandstone has been definitely located as 

 far south as the North Canadian River and consequently the limits of the southern part of the 

 Ralston group, which is exposed in Lincoln, Oklahoma, Pottawatomie, Cleveland, McClain, 

 and Garvin counties, can not be accurately demarked. In the northern part of the State this 

 group is exposed in Osage, Kay, Pawnee, Payne, and Lincoln counties. 



Stratigraphy. — The equivalents of the following formations in Kansas, the combined 

 thickness of which is approximately 800 feet, are included in the Ralston group as the latter 

 is exposed in northern Oklahoma: Lecompton limestone, Tecumseh shales. Deer Creek lime- 



« Beede now considers the Elmdale as the provisional base of the Permian. 



