Review of the New York Geological Reports. 65 
aspect ; for the corniferous limestone is more compact, of a finer 
grain, and contains many more flinty layers ‘and nodules than the 
last described formation. ‘Though mostly of light grey or blu- 
ish tints, the corniferous rock assumes, at some localities, espe- 
cially at Black Rock, a very dark color. It is more persistent in 
its lithological character than the Onondaga limestone, and of 
greater thickness, varying from twenty to seventy feet. © 
Along with the last-formation, it forms the upper calcareous 
terrace of the Helderberg range, and with the Onondaga salt 
group forms the second limestone terrace south of Lake Ontario 
in Hatv’s district. 
Its range and outcrop are represented on the chart by the same 
blue band that marks the limits of the last formation which it 
immediately overlies, and with which it is coéxtensive, appear- 
ing, however, always as the thicker and more prominent member. 
These together with the previously described members of this 
division, have a southerly dip and pass under the Marcellus shale. 
The corniferous limestone imparts to the scenery of a country 
where it prevails, a peculiar and constant feature ; for “all the 
small streams as they pass over it, form rapids or cascades of more 
or less extent.” It is the barrier at the outlet of Lake: Erie, and 
the rapids at Black Rock are produced by — of the wa- 
ters of the Niagara River over its beds. 
Like the preceding, it often lies regllaliy jointed i in the quar- 
ries. At Seneca there are dislocations of such a nature that seem 
to indicate an undermining ; this has been attributed to the re- 
moval of the soft gypsum rock beneath. 
Instead of the corals and Crinoidea of the last formation, we 
find in the corniferous hardly any thing but shells. Hatt is of 
opinion that about the time of the deposition of this rock, the 
bed of the.ocean sunk beyond the influence of the light and the 
particular temperature favorable for the growth of Polyparie ; 
and by oscillations of the surface, the previously existi 
of that order were overwhelmed and covered up by a calcareous 
mud. 
The most fossiliferous part of this ‘ot is the upper portion, 
when free from hornstone and chert. “ Amongst these are two 
trilobites, the Odontocephalus selenurus of Green, Fig. 1, Pl. 33, 
(Vanuxem’s report,) and a Calymene. So abundant is the fons 
mer of these at Schoharie and — a that it alone is the a 
Secosp Serizs, Vol. I, No. 1.—Jan. 1 
