io8 Bulletin 12 236 



The Indiana Geological Report for 1874 contains a report on a 

 colledlion of Black shale fossils which were submitted to Mr. R. 

 P. Whitfield. The study of these led Whitfield* to the conclu- 

 sion that the Black shales of Indiana "are in part at least equiv- 

 alent to those known as the Genesee slates of New York," and 

 "that they represent an equivalent in time to that of the entire 

 Hamilton epoch as represented in New York, and perhaps even 

 some of the overlying beds." 



In 1877 Prof. Shalerf stated that he considered the Black shale 

 in Kentucky to represent the whole of the Devonian down to the 

 top of the Oriskany. This conclusion is based upon the apparent 

 conformity of the Black shale with supposed Oriskany sandstone 

 in Central Kentucky. 



Previous to 1879 Prof. Hall had considered the Devonian lime- 

 stone in southern Indiana to represent only the Upper Helderberg 

 group. The Hamilton, if present at all, he considered to be rep- 

 resented by some part of the Black shale. In the Report on the 

 Paleontology of New York| published in 1879 he published a 

 very instru(5live tabulation of the Hamilton species which he had 

 recognized in the "Hydraulic beds and associated limestones at 

 the Falls of the Ohio." He concludes from the evidence pre- 

 sented that the "Hydraulic and Encrinital limestones" at the 

 Falls of the Ohio are the equivalent of the Hamilton. In the 

 same paper Hall reviews the question of the age of the Black 

 shale in Indiana and states that ' 'the Black shale of the west is 

 equivalent and even the absolute continuation of the Black shales 

 succeeding the Hamilton group of New York (the Genesee 

 slate)." II 



In 1884 John Collett, State Geologist of Indiana, published a 

 geological map§ and section of the State in which the Hamilton 

 is not recognized. The following classification of the formations 

 between the Coal Measures and the Upper Silurian is given: 



*6th Ann. Rept. Ind. Geol. Surv., pp. i8i, 182. 



fKy. Geol. Surv., n. 3, vol. 3, pp. 173, 174. 



JPal. N. Y., vol. 5, pt. 2, pp. 139-154. 



||Ibid, p. 152. 



113th Rept. Ind. Dept. Geol. and Nat. Hist. 



