90 BULI.ETIN 12 2l8 



Still Hot quite willing to agree with de Verneuil as to the Carbon- 

 iferous age of all the sandstones and shales above the Black shale, 

 and says: ' 'The green shales and yellow sandstones of Ohio and 

 Indiana which succeed this black shale have been recognized as 

 Carboniferous by their fossils, though there is still some doubt 

 whether the lower part may not represent the Chemung group of 

 New York."* 



In 1 85 1 Mr. Christy, in a communication to the American As- 

 sociation,! announced that he had found the Rockford limestone 

 to be centrally located in the Black shale, about thirty feet of shale 

 lying above it. This conclusion has since been shown to be eron- 

 eous. All who have since studied the stratigraphy of these form- 

 ations concur in placing the Rockford limestone at the top of the 

 Black shale. 



D. D. OwenJ: classed the "Knob formation" of Kentucky as 

 the base of the sub-carboniferous in 1856. In i860 Meek and 

 Worthen in describing a new Sphenopterium from the Rockford 

 limestone stated that the specimen is "from beds probably of 

 Upper Devonian age, but containing Carboniferous Goniatites.'"\\ 



In 1 860 Sidney L,yon§ published a se(?tion of the rocks of Ken- 

 tucky, in which he classed with the "Sub-carboniferous Series" 

 the "Knobstone Beds," as well as the beds below them, down to 

 and including the Catinopora beds of the Niagara. 



In a paper published by Prof . Hall^ in 1861 he attempts to 

 prove the parallelism of the Rockford limestone and the band of 

 limestome occurring in the midst of the Marcellus shale. In this 

 paper the Rockford Goniatites are considered of Hamilton age 

 and the Knob sandstone and shales "are recognized as of the age 

 of the Chemung group of New York." 



*Foster and Whitney's Rept. on Geol. L,. Sup. L,and. Dist., pt. 2, p. 307. 

 fProc. Am. Assoc, vol. 5, p. 76. 

 jKy. Geol. Rept., vol. i, p. 89. 



II Description of New Carboniferous Fossils from Illinois and Other 

 Western States, Proc. Phil. Acad. Nat. Sci., Sept. i860, p. 447. 

 ^Trans. St. Louis Acad. Sci., i, pp. 614-619. 

 ^i3th Rept. N. Y. Regents, p. 95. 



