1897.] DIJAKE — THE GEOLOGY OF INDIAN TERRITORY. • 300 



which change rapidly in most of them. These variations are appa- 

 rently greater in the Indian Territory than they are in Arkansas. 

 In the northern part of the Indian Territory it is doubtful whether 

 the group is represented by any deposits of consequence. It is rep- 

 resented southeast of Vinita by a series of shaly clays and thin beds 

 of impure limestones, aggregating about seventy-five feet in thick- 

 ness. East of Chouteau, along Grand river, the group is about one 

 hundred feet thick and is rather clearly divided into different beds 

 of limestones and shales. On Salisaw creek and eastward to the 

 Arkansas-Indian Territory line, the group is about one hundred and 

 fifty to two hundred feet thick. The whole group, as outlined in 

 Washington county, Ark., is, however, nowhere in the area studied 

 represented in a characteristic way. The Archimedes and Pentre- 

 mital limestones are usually together, and it is very doubtful whether 

 the Kessler limestone is at all represented. 



This group is usually confined to an escarpment and isolated 

 hills along the western and southern border of the Boone chert and 

 limestone area; at most its outcrop forms a belt only two or three 

 miles wide along the border of the Lower Carboniferous. Sees. 

 a-k, PL V, show the development of this group along its line of 

 outcrop from near Still well to near Vinita. The hills east, west 

 and south of Stillwell are capped by fifty to seventy-five feet of 

 limestone that belongs to this group. The limestone is usually gray 

 in color, rather massive and in places quite arenaceous. Farther 

 westward, in the isolated hills south of Wauhillau, near the Evans- 

 ville-Tahlequah road, the limestone and beds of the Boston group 

 are considerably thinner and are overlain by sandstone that is prob- 

 ably Coal Measures. Ten to twenty-five miles south and southwest 

 of Wauhillau, near Bunch, Marble, Vian and along Illinois river' 

 east of Greenleaf, the Boston group is one hundred and fifty to two 

 hundred feet thick and probably thicker, since the dividing line 

 that has been used to separate this group from the Coal Measures is 

 largely an arbitrary one and the doubtful beds are mostly classified 

 as Coal Measures. One and a half miles northwest of Marble the 

 lower part of the Boston group beds consists of about one hundred 

 feet of gray limestone slightly interstratified with clay shale and 

 arenaceous shaly limestone. Archimedes occur frequently in the 

 lower part of the limestone bed. Overlying this limestone there 

 is a series of strata aggregating about two hundred feet in thickness, 

 which are composed of sandstones and some interstratified clay shale. 



