362 DKAKE — THE GEOLOGY OF INDIAN TERRITOKY. [Sept. 3, 



The second area is a strip about four miles wide and twenty-two 

 or twenty-three miles long which extends into the Territory along 

 the Backbone anticline. The third one is an irregular belt border- 

 ing the Lower Carboniferous on the south and west. The most of 

 the southern part of this belt lies near and to the north of the 

 Arkansas river, and includes the Boston mountains; the western 

 part of the belt extends along the Missouri, Kansas and Texas rail- 

 way from Wagoner to Vinita, and from Vinita it runs northeasterly, 

 passing into Kansas at and southwest of Baxter Springs. Along the 

 Arkansas-Indian Territory line this belt is about twenty miles wide, 

 but it gradually narrows to the westward and northwestward until 

 north of Wagoner it is usually but four to five miles wide. 



Lithology of the Lower Coal Measures. — Throughout this group 

 there is such a constant repetition of arenaceous gray, clay shales 

 and sandstones of uniform character that the lithology and stratig- 

 raphy are exceedingly monotonous. 



There is, however, some marked variation introduced by the 

 grits and conglomerates at the base of the group north of the 

 Arkansas river, and by the limestones south of Ponola, Wilburton 

 and Hartshorne. Some minor variations in color and composition 

 also occur in the shales and sandstones. The sandstones are usually 

 massive, but in places they are flaggy or shaly and micaceous, argil- 

 laceous, calcareous, ferruginous, or bituminous. A little quartzite 

 occurs in the Windingstair mountains and some conglomerates 

 may be seen in the vicinity of Thomasville. 



Thickiiess of the Lower Coal Measures. — The greatest thickness 

 observed in the Lower Coal Measures was in the southeastern part 

 of the field. In this locality the strata throughout show little vari- 

 ation ; extensive faults lie along the north side of Walker, Black 

 Fork, Windingstair and Kiamichi mountains, and smaller faults 

 at other places ; and overthrows occur at some places to further 

 complicate the interpretation of the stratigraphy. On account of 

 these difficulties, as well as the limited amount of work the recon- 

 naissance would allow, only rough estimates of the thickness of the 

 exposed beds will be attempted. 



The longest continuous section studied in this part of the field 

 was from the base of the Poteau mountains to the south side of 

 Rich mountains. This section extends north and south about 

 three or four miles west of the Arkansas-Indian Territory line. 

 The stratigraphy somewhat generalized along this line is shown in 



