140 
PALAEONTOLOGY OF NEW YORK. 
limestone (the great coral reef, comprising the Onondaga and Corniferous lime¬ 
stones of the New York system) seems to have been originally unbroken, at 
least from the valley of the Hudson nearly and perhaps quite to the line of the 
present valley of the Mississippi. It is traceable in unbroken continuance from 
the Hudson to the Niagara rivers, and through Canada west to Lake Huron, and 
thence into Michigan; while in a southwesterly direction are the outcrops on 
the two sides of the Cincinnati axis, extending through Ohio and Indiana, and 
thence into Kentucky, where it gradually thins out. During the formation 
of this remarkably extensive coral reef, there could have been no great change 
in the conditions of the ocean; for not only do these corals indicate an undis¬ 
turbed and luxuriant growth, but the same genera and the same species prevail 
over a large part of the above area. It is only in the superjacent beds that 
we may look for changed conditions, which have given origin to the different 
terms used to designate the subdivisions of the formation in different parts of 
the country. 
In New York we have the following members of the series, between the 
Marcellus shale and Oriskany sandstone: 
1. Marcellus shale. 
2. Limestone with Ichthyic remains (bone 
bed)... 
i 
3. Cherty beds, with species of Loxonema, 
Upper Helderberg Pleurotomaria, Bellerophon, etc. . 
group. 4. Corniferous limestone. 
5. Onondaga limestone (the great coral¬ 
bearing limestone). 
6. Schoharie grit. 
7. Oriskany sandstone. 
* In the arrangement of Prof. Eaton, all the limestone formation between the Schoharie grit and Mar¬ 
cellus shale was termed “ Corniferous limestone ”—no subdivisions being recognized. In the reports on the 
Geological Survey of New York, the subdivision into Onondaga and Corniferous limestones was made for the 
convenience of reference, and on account of the character of the prevailing fossils in the two members. 
Farther investigation has shown the existence of a peculiar Cherty bed containing characteristic fossils, and 
also a Calcareous bed with remains of tishes ; both of which are distinct from the Onondaga and Corniferous 
The Corniferous 
limestone of 
Eaton.* 
