366 DEAKE — THE GEOLOGY OF INDIAN TEKRITORY. [Sept. 3, 



variation lithologically from the beds described to the northward ; 

 there is, however, a great increase in the thickness of the deposits. 

 The east and west folding in this area has made it possible to get 

 moderately long exposures of the same strata along the axial direc- 



i a f- Scalg a^ JVLiles JO /& , /£ ^ 



Sec. No. 8. Across the Lower Coal Measures, south of Poteau mountain. 



tion of the folds. The three groups of strata shown in Sec. 8 are, 

 with modifications, extended to the westward the full length of the 

 area. The faulting along the north side of Walker mountains, 

 along Fourche Melane valley and south of Hartshorne, separates the 

 group on the north from the Central or Walker mountain group. 

 The central and southern groups are in part repetitions of the same 

 strata. The second group comprises the strata of Walker moun- 

 tains. Blue mountains and nearly all the strata lying between Bengal 

 and Hartshorne. The beds between Hartshorne and Bengal are 

 referred to the second division rather doubtfully, since this necessi- 

 tates an upthrow of about six thousand feet along the faulted belt 

 south of Hartshorne and along Fourche Melane valley. Such a 

 throw would require the strata in a block about one and three- 

 quarter miles wide to be tilted at an angle of 45° to the south. 

 South of Hartshorne, as shown in Sec. 10, the strafa are tilted at 

 angles of 40"" to 50° for a distance of about two miles and possibly 

 farther. This tilting is only slightly offset on the north side of the 

 fault line by gentle dips of 4^ to 5°. So it seems probable that the 

 throw is as much as six thousand feet at this place. South of Wil- 

 burton and southwest of Red Oak the strata on the south side of the 

 Fourche Melane valley do not dip very much more steeply than 

 they do on the north side, and as the dips are in opposite directions 

 the beds appear to be the same. They are, however, not the same, 

 for the coal beds are not repeated on the south side of the valley. 

 Furthermore, the strata are different lithologically, since limestones 

 occur on the south side and may be traced westward to the lime- 

 stone beds south of Hartshorne, which beds have been shown to 

 probably belong six thousand or seven thousand feet below the 



