THE LOUISVILLE LIMESTONES. 
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THE LOUISVILLE LIMESTONES. 
NOTE ON THE HYDRAULIC BEDS AND ASSOCIATED LIMESTONES AT THE FALLS OF THE OHIO. 
At the Falls of the Ohio and adjacent localities, the lowest beds of the 
limestone formation are marked by the presence of Halysites catenulatus, and 
for a long time have been locally known as the “ Catenipora beds.” This 
Silurian limestone is succeeded by the great coral-bearing Devonian limestone, 
which is everywhere, in that part of the country, a well defined geological 
horizon; and though the higher beds of the formation are distinguished by 
the presence of other fossils than corals, there is no marked physical change 
from the base to the upper stratum which is characterized by Spirifera acumi- 
nata. The whole is more generally recognized by its numerous corals, and 
the genera Favosites, Michelinia, Zaphrentis, Heliophyllum and Cystipiiyllum 
are prevailing forms.* This limestone is succeeded by beds of an argillaceous 
magnesian limestone, known as the •“ Hydraulic limestone,” which gradually 
merges above into thin, slaty beds, some of which are highly siliceous, and 
these are followed bv what is known as the “ Encrinal limestone:” the whole 
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terminated above by the black slate. This entire limestone formation above 
the “ Catenipora beds” has been generally, if not universally, recognized as of 
the age and the western extension of the Upper Ilelderberg group of New 
York (representing all that was originally included by Eaton under the 
designation of Corniferous limestone and Schoharie grit). I have accepted 
and advocated this view of the age of these formations, which seemed to be 
sustained by large numbers of identical fossils from the two distant regions; 
and I believe that their relative age has not, up to the present time, been called 
in question. 
As might naturally be expected, the subdivisions recognized in the east and 
in the west do not always coincide, but it is usually quite possible to correlate 
these different members by a comparison of their fossil contents. The main 
* It was from the presence, in this locality, of numerous species of Corals, identical with those of the 
New York formations, that, in 1841, I recognized these limestones as of the same age. 
