154 
NEW YORK PALAEONTOLOGY. 
Since the Spirifera gregaria and Sp. acuminata are characteristic fossils of the 
Corniferous limestone in all the western localities, it is clear that the hydraulic, 
siliceous and crinoidal beds of the sections in the vicinity of Louisville have 
thinned out, and are represented only by the few inches of oxide of iron which 
has accumulated at this place during the deposition of the limestones in other 
localities. In other sections, however, the oxide of iron is represented as 
lying between the Hydraulic limestone and the Black slate, showing a lapse 
of time and the absence of some member of the series; but in nearly all the 
sections, the Hydraulic limestone, with its associated or equivalent beds, is 
represented in greater or less force, the thickness varying from a trace, to six 
or eight or even twelve feet in the counties of Scott and Jefferson; while in 
some localities in Clark and Floyd counties, it reaches a thickness of twenty 
feet or more. 
In a general section of the geological formations of Clarke and Floyd 
counties, given in the Report of 1873, Prof. Cox doubtfully refers the Crinoidal 
and Hydraulic limestones to the Hamilton group: * 
Knob limestone—-Keokuk group 
Knob sandstone, 1 lr - , , , __ 
Knob shale, } Kinderhook group . . . 
New Albany Black slate, 
Crinoidal limestone, >(?) Hamilton group 
Hydraulic limestone, ) 
Corniferous limestone—Upper Helderberg group 
Utica limestone—Niagara group 
Magnesian limestone—Clinton group . 
Madison limestone—Cincinnati group 
80 feet. 
. 344 feet. 
140 feet. 
. 22 feet. 
52 feet. 
. 30 feet. 
207 feet. 
In the Report of 1874, p. 123, Prof. Cox gives the relations of the New 
Albany black shale with the superincumbent rocks, indicating it as the equiva¬ 
lent of the Genesee shale of New York. 
* Report of 1873, p. 172. Since this reference does not appear in succeeding reports, the view then 
entertained may have subsequently been modified. This section had escaped my attention in looking for 
authorities regarding the age of the upper limestones of the Palls of the Ohio, and should have been cited 
in its proper place in the preceding pages. 
