1897.] DRAKE— THE GEOLOGY OF INDIAN TERRITORY. 379 



beds of the above-named mountains, since the same strata decrease 

 in thickness to the westward and especially to the northward. This 

 group, in the main, consists of arenaceous gray clay shales and 

 massive sandstone beds, but in the northern region limestone beds 

 are included in the group. The sandstone beds of this group are 

 somewhat more massive than they are in the Cavaniol group, as is 

 shown in Plate VIII. In the southeastern region nearly all the sand- 

 stones are massive, but southwest of Enterprise they are frequently 

 ripple-marked and thin-bedded. Three miles south of South Cana- 

 dian, sandstones form a prominent escarpment about one hun- 

 dred feet high. This sandstone is composed of strata that are 

 usually massive, but sometimes flaggy, so that beautiful smooth 

 flags of varying thickness are common. Five or six miles farther to 

 the west, the dark-gray clay shale overlying this bed contains some 

 black carbonaceous fossiliferous limestone nodules. The shales along 

 Salt creek five miles east of Calvin are light gray, very arenaceous, 

 and carry some thin shaly layers of calcareous sandstone that are 

 quite fossiliferous. The sandstone beds, so prominent a feature of 

 this group in the southeast and southern region, gradually grow less 

 prominent to the northward, but as far north as McDermitt they 

 are the prevailing strata. A section across this group in the vicinity 

 of Sapulpa is as follows : 



FEET. 



1. Massive and slightly friable sandstones and a 



little interbedded clays and shales 400 



2. Clay shale 100 



3. Massive, rather friable sandstones 200 



4. Gray clay shale, calcareous in places, and con- 



taining two feet of limestone about one 

 hundred and fifty feet from the base of the 

 bed 100 



A section across this group west of Oologah shows the following 

 sequence of strata: 



FEET. 



1. Sandstones interbedded throughout with arena- 



ceous clay shale 200 



2. Fossiliferous shaly limestone 3 



3. Clay shales and shaly sandstone 50 



4. Hard, massive, gray limestone 25 



