378 DRAKE — THE GEOLOGY OF INDIAN TERRITORY. [Sept. 3, 



importance to the Oologah limestone is Bed 5 of the Adair-Paw- 

 huska section. This limestone is beautifully exposed in bluffs along 

 the east bank of Verdigris river, quarter of a mile below the 

 McClellan ford east of Talala. At that place it contains no chert 

 nodules, but in other lithologic characteristics it closely resembles 

 the Oologah limestone. 



Poieau Group. — Dr. J. P. Smith was the first to introduce, the 

 name Poteau in connection with strata included in this group. ^ It 

 is probable that the Poteau mountain beds do not extend so high as 

 the base of the Permian, but the name *' Poteau group" will be 

 applied to the group of beds between the Cavaniol group and the 

 base of the Permian, as outlined in this paper. The dividing line 

 used to separate the Poteau group from the Permian is merely an 

 arbitrary one, and is, in the main, based on the fossils found at dif- 

 ferent localities. The beds of the Poteau group lie in small isolated 

 areas and in a long belt-like area. The isolated areas are the upper 

 parts of Poteau, Sugar Loaf, Cavaniol, Sans Bois, Tucker Knob and 

 McChar mountains. The long belt-like area lies on the west side 

 of the Cavaniol group throughout the field and has an average 

 width of fifteen to twenty miles. The beds of this area are 

 tilted to the northwest, where they lie against the western limit 

 of the folded region of the Choctaw coal field, but further to the 

 north the beds dip gently to the westward or a little north of west- 

 ward. Throughout this belt the outcropping hard rock beds form 

 east and southeast facing escarpments. 



The Mayberry coal bed was not definitely located in either the 

 Sugar Loaf or the Poteau mountains, but as these mountains do not 

 appear to be situated in quite such deep synclines as the Cavaniol 

 or the Sans Bois mountains the coal must be at a somewhat higher 

 elevation. All four of these mountains are nearly the same in 

 elevation — between twenty-five hundred and three thousand feet. 

 From fifteen hundred to two thousand feet of the upper part of the 

 Cavaniol and Sans Bois mountains belong to the Poteau group 

 and twelve hundred to fifteen hundred feet of the tops of Sugar 

 Loaf and Poteau mountains belong to this group. The group 

 northwest of McAlester is about two thousand feet thick, but prob- 

 ably the top beds represent somewhat higher horizons than the top 



1 Jour. Geol.,No\. ii, pp. 194-196, and Proc. Amer. Phil. Soc Vol. xxxv,. 

 No. 152, p. 17. 



