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



The '' Black shale " of Tennessee was referred to the Devonian ^ 

 by Safford. The Eureka shale of Arkansas was referred doubtfully 

 to the Devonian.' Dr. Branner thinks the shale belongs to the 

 Lower Carboniferous,' because in places it grades into the over- 

 lying Lower Carboniferous limestones, and the few fossils that 

 have been found in the shale belong equally to the Devonian and 

 the Lower Carboniferous. The persistency with which such a thin 

 bed occurs unconformably with the Silurian and conformably with 

 Lower Carboniferous beds in the Territory, as well as in Arkansas, 

 also strengthens the theory that it is Lower Carboniferous. 



Spavinaw Creek ^r<?^.— Exposures of the shale are common 

 around the border of the Silurian area on Spavinaw creek. One of 

 the best exposures seen there was about one mile west of Spavinaw 

 post-office, on the north side of Spavinaw creek. At that point it 

 is about forty feet thick, and is the usual typical, bituminous, 

 rather friable shale. 



Illinois River Areas. — On the north side of the Illinois river, 

 west of the Cincinnati-Siloam Springs road, and near the Arkansas- 

 Indian Territory line, good exposures of the shale may be seen. 

 Near the Stewie ford of the Illinois river, along the Cincinnati- 

 Oaks road, the shale outcrops again. In the limited area examined, 

 no complete section was seen, but it appeared to have its usual 

 thickness and characteristics. West of Bunch, at a point about 

 four miles below the mouth of Elk creek, the Eureka shale outcrops 

 in the bed of the Illinois river. 



Salisaw Creek Areas. — About two miles northwest of Bunch, along 

 Marble creek, the valley shows the typical Eureka shale soil, but no 

 good exposures of the shale were seen there. Along Walkingstick 

 creek, however, about three and a half miles north of Marble, 

 good exposures of the shale may be seen. At this locality it is 

 about thirty feet thick and contains some calcareous nodules, other- 

 wise it does not vary from its general characteristics. Along Dry 

 creek, one and a half miles northwest of Marble, good exposures of 

 the shale show it to be about thirty feet thick. 



'^ Eletneiitary Geol. of Tenn., by James M, Safford and J. B. Killebrew, 

 Nashville, 1885, pp. 112, 118. 



''■Ann. Rept. Geol. Sur. Ark., 1891, Vol. ii, p. 32, 



3" Phosphate Deposits of Arkansas," Trans. Am. Inst. Min. Eng., loc. cit. 



