6i6 L. C. SNIDER 



This lower limestone member is correlated with the St. Joe 

 limestone (marble) member of the Boone formation in Arkansas. 

 It is well exposed in the Siloam Springs quadrangle along the Illinois 

 River and some of its tributaries, along Spavinaw Creek in the 

 Siloam Springs and Pryor quadrangles, and along the larger tribu- 

 taries of Grand (Neosho) River in the Vinita and Wyandotte 

 quadrangles. From collections made along the Illinois River in the 

 Siloam Springs quadrangle, the following brachiopods have been 

 identified: Rhipidomella michelinia L'Eveille, Chonetes logani 

 N. and P., Productus fernglenensis Weller, P. sampsoni Weller, 

 P. sp., Spirifer grimesi Hall, S. vernonensis Swallow, S. fern- 

 glenensis Weller, 6*. choteauensis Weller, Spiriferina suhtexta White, 

 Cyrtina hurlingtonensis Rowley, Reticularia pseudolineata Hall ( ?) , 

 Cleiothyris royssi L'Eveille (?), Athyris lamellosa L'Eveille, and 

 Ptychospira sexplicata W. and W. The remainder of the fauna 

 has not been studied, but the corals and some of the bryozoa 

 appear to be identical with those described by Weller'^ from the 

 Fern Glen formation, and which occur in the lower beds described 

 in the next paragraph. 



Locally there are darker-colored limestones with greenish 

 shales below the St. Joe member. Taff describes these as occurring 

 in one outcrop near the northern border of the Tahlequah quad- 

 rangle, where they have a thickness of 6 feet. A few miles to the 

 north in the Siloam Springs quadrangle these same dark-colored 

 limestones and green shales reach a thickness of about 40 feet, 

 but they vary greatly in thickness in very short distances. The 

 fauna of these rocks shows them to be equivalent to the Fern Glen 

 formation of Missouri. To the northwest these rocks thin rapidly 

 and in the northeastern part of the Pryor quadrangle along Spavi- 

 naw Creek, and in the southeastern part of the Vinita quadrangle 

 along Big Cabin Creek there is only a layer of soft green clay shale, 

 less than a foot thick, between the Chattanooga shale, and the 

 St. Joe member of the Boone. Although no fossils have been found 

 in this shale layer, it is believed to represent the Fern Glen on 

 account of its character and position. 



'Stuart Weller "Kinderhook Faunal Studies," V, The Fauna of the Fern Glen 

 Formation, Bull. G. S. A. xx, 265-332. 



