williams.] ORTON'S CLASSIFICATION OF OHIO ROCKS. 



189 



Subcarboniferous. 



250-3,000 



75 



Devonian. 



12. Subcarboniferous limestone, Maxville, Newtonville, 



efcc 25 



Tile. Logan group 0-350 



j lid. Cuyahoga shale 150-450 



11. Waverly group., > lie. Berea shale 20-50 



J 116. Berea grit „ 3-160 



Ilia. Bedford shale 50-150 



flOe. Cleveland shale. ] 



10. Ohio shale J 10&. Erie shale . I .. . 



[l0«. Huron shale. 



9. Hamilton shale, Olentangy shale 



8. Devonian limestone, Upper Helderberg or Cornifer- 



ous, including West Jefferson sandstone 



7. Lower Helderberg limestone, etc. 



In this classification the Logan group is the equivalent of the Olive 

 shales of Read, the Logan sandstone and the Waverly Conglom- 

 erate of Andrews. The " Berea shale" is a name proposed by Mr. 

 Meek for the " Waverly black shale " of the reports. The " Waverly 

 group" is differently delimited from the original Waverly group of the 

 first and second reports, by the addition of the Logan group at the 

 top and the exclusion of the Cleveland shale at the bottom. The rea- 

 son for including the Cleveland shale in the Devonian was explained 

 by Dr. Orton in previous papers. It is because of structural consider- 

 ation which led to associating the three shales of Newberry in one 

 formation, though there were recognized fossils in some of them which 

 have been regarded as strictly belonging to the higher fauna. 1 



The correlation of the Goniatite limestone of Eockford, Indiana, in- 

 volved a number of disputed questions, in all of which the fossils 

 pointed to the right interpretation, while the apparent stratigraphy 

 was misleading. 



The elements of the problem were these : At Eockford a limestone, 

 rich in Goniatites, was found above the black shale, and stratigraphi- 

 cally below arenaceous deposits and shales, which in other places were 

 followed by the Mississippian limestone. In I860, 2 a number of Gonia- 

 tites and other fossils were described, and the author, Mr. James Hall, 

 reported the lim estones as Marcellus black shale. He had previously 

 interpreted the black shale of the Southwest as Marcellus, and as the 

 Marcellus shaleof New York in calcareous layers was rich in Goniatites, 

 he inferred that the bed at Eockford was the equivalent. 



In this paper he said : 



The parallelism of these localities is inferred from the fact that the stratum con- 

 taining the Goniatites is clearly above the limestone of the age of the Upper Helder- 

 berg group, and below the sandstones which are recognized as of the age of the 

 Chemung group of New York. The exposures at the immediate locality are obscure ; 

 but the black shale, which I regard as the continuation of the Marcellus shale, occurs 

 in the immediate neighborhood. 3 



1 Vol. VI., Economic Geology, by Edward Orton Columbus, 1888, p. 29. 



2 Thirteenth Report to the Regents on the State Cabinet of Natural History, Albany, N. Y. 

 * Ibid., p. 95. (See Cristy'a paper on the Goniatite limestone 1851). 



