MISSISSIPPIAN ROCKS OF NORTHEASTERN OKLAHOMA 615 



published several years ago. The Wyandotte quadrangle was 

 surveyed by C. E. Siebenthal in 1907, and the Vinita quadrangle 

 by D. W. Ohern in 1909, but the folios have not been published. 

 The references to the geology of the Tahlequah and Muskogee 

 quadrangles are to be attributed to the folios (Nos. 122 and 132 

 respectively) of the Geologic Atlas of the United States, prepared 

 by Joseph A. Taff. It is not thought necessary to give footnotes 

 for the individual references. 



STEATIGRAPHY AND PALEONTOLOGY 



The Mississippian rocks of Northeastern Oklahoma comprise 

 the following formations named from the base up: Boone forma- 

 tion, unnamed limestone, Fayetteville shale, and Pitkin limestone. 

 The stratigraphy of all these formations varies considerably as the 

 outcrops are followed west from the Arkansas line along the south 

 side of the area and then north along the west side. 



Boone formation. — The Boone formation covers by far the greater 

 part of the area under consideration. In the Tahlequah and 

 Siloam Springs quadrangles some of the deeper valleys are cut 

 through the Boone into the underlying Devonian, Silurian, and 

 Ordovician rocks, but the outcrops of these rocks are narrow and 

 the Boone covers all the area indicated, except a comparatively 

 narrow belt around the margin, which is occupied by the younger 

 formations, and the outliers of these formations. 



The Boone consists principally of limestone and chert, with a 

 total thickness of from 100 to 350 feet. At or near the base of 

 the formation there is locally a limestone member of up to 30 

 feet or even more in thickness. The upper part of this limestone 

 is free from chert, thick-bedded, light-colored, and crinoidal. 

 Near the Arkansas line, in the Tahlequah quadrangle, the lime- 

 stone is locally absent so that the cherts rest directly on the 

 Chattanooga shale. In no place in this quadrangle is the limestone 

 reported as being over 15 feet in thickness. This thickness is 

 exceeded in the Siloam Springs quadrangle, and the limestone is 

 continuous to the northwest so far as observed. In the northern 

 part of the area there are several feet of shaly limestone and flaggy 

 limestone below the thick, crinoidal ledge which in this region is 

 10 to 15 feet thick. 



