1897.] DEAKE — THE GEOLOGY OF INDIAN TERRITORY. 363 



Sec. 8 (p. 366.) The strata exposed along this section are divided 

 into three divisions by two faulted areas. The division on the north 

 is about seven thousand feet thick, the one next further to the south 

 is about eleven thousand feet thick, but possibly contains as much 

 as six thousand feet of strata that is repeated from the first division, 

 thus leaving only five thousand feet to be added to the seven thou- 

 sand of the first division, which gives twelve thousand feet. The 

 third and last division is about fifteen thousand feet thick. In this 

 the heavy sandstone beds in the south side of Black Fork and 

 Rich mountains are each about one thousand feet thick, and are 

 so much more massive than any of those exposed to the north, 

 that they are probably lower horizons. There is a strong probabil- 

 ity, however, that the strata of Black Fork and Rich mountains are 

 the same, which is the case if the beds are overthrown to the north, 

 as they appear to be. If this is the case, only five thousand 

 feet of the thickness of the strata of the two mountains, should 

 be added to the section already estimated. The remaining five 

 thousand feet of strata to the north of Black Fork mountain is most 

 likely a repetition of the strata exposed and counted farther to the 

 northward. So only five thousand feet more can safely be added 

 to the twelve thousand feet, which gives a total thickness of seven- 

 teen thousand feet. 



It is possible that this section represents a thickness of as much 

 as twenty-five thousand feet of strata, but under the observed con- 

 ditions, seventeen thousand feet seems more probable, and even 

 that may be too much. The base of the formation was not seen, 

 but as the thickness exposed is very nearly as much as the estimated 

 thickness of the whole formation in Arkansas,^ it is probable that 

 almost the total thickness of the beds is exposed in this section. 

 The Lower Coal Measures in Arkansas, however, run a little higher 

 in the section than they do in the Indian Territory, since the 

 Huntington Coal belongs to a higher horizon than the coals farther 

 to the east in Arkansas." 



Stratigraphy of the Lower Coal Measures. — The basal beds of 

 the Lower Coal Measures appear to be exposed only in the Chero- 

 kee Nation. Overlying the Lower Carboniferous there is a series 

 of sandstones, grits and shales which belong to the basal beds of 



iDr. Branner estimates the thickness of these Lower Coal Measures in Arkan- 

 sas to be 18,480 feet thick {Amer. Jour. Sci., Vol. ii, September, 1896, j). 235) 

 "^Geol. Surv. 0/ Ark., Ann. Rep., 1888, Vol. iii. 



