864 J)RAKE — THE nEOLOGY OF INDIAN TEREITORY. [Sept. y, 



the Coal Measures. No definite division between the Lower Car- 

 boniferous and the Coal Measures could be fixed, but the fossils 

 found in the highest strata, known to belong to the Boston group, 

 are a mingling of species belonging to the highest Lower Carboni- 

 ferous and the Coal Measures. These sandstones, grits and shales 

 have the same lithological characteristics and stratigraphic position 

 as the so-called Millstone grit of the Geological Survey of Arkan- 

 sas.^ There is every gradation from the smooth, fine-grained sand- 

 stones to the grits and coarse conglomerates. Good examples of 

 the grit may be seen, north of Camp Track, five miles south of 

 Bunch, in places three to four miles northwest of Vian, and along the 

 east side of Illinois river west-northwest from Marble. This grit is 

 composed of angular grains of quartz, which are usually from one 

 to two millimetres in diameter, but occasionally are from five to six 

 millimetres in diameter. Hematite usually forms the cementing 

 matter for the grit. The basal group of the Lower Coal Measures 

 in the Cherokee Nation is composed mainly of sandstones and grits 

 throughout. No section was made of this group along the Arkan- 

 sas-Indian Territory line, but it is probably not less than two thou- 

 sand feet thick. Five to ten miles southeast of Ft. Gibson it is three 

 hundred feet thick ; from eight to ten miles northeast of Ft. Gib- 

 son it is about two hundred feet thick. From this place further to the 

 north it rapidly thins until from about ten miles north of Wagoner 

 to near Baxter Springs, Kans., it is but five to fifteen or twenty feet 

 thick. In this northern part of the field the grit is usually lacking 

 and the sandstones are very variable. These basal sandstones cap 

 the isolated hills and east-facing escarpments from four to six 

 miles south of Chouteau, one and a half miles south of Vinita, 

 three miles west of Afton, one mile south of Miami, and about two 

 miles south of Baxter Springs, Kans. There is a bed of gray, are- 

 naceous clay shale two hundred and fifty to three hundred feet 

 thick overlying this group of sandstones and grits throughout the 

 Cherokee Nation. This shale is somewhat thicker in the northern 

 part of the field than it is toward the south. It comprises nearly 

 all the Lower Coal Measures strata that lie west of Grand and 

 Spring rivers and throughout that area it is marked by level or 

 gently undulating prairie plains. 



The southern extension of the Lower Coal Measures area of the 

 Cherokee Nation outcrops along the Milton-Bokoshe anticline 



1 Ibid., Vol. iv, p. io6,' and 1890, Vol. i, pp. 113-II5. 



