Chemung and Catskill.— Stevenson. 
it in the Secondary with the coals west of the Alleghanies, thus 
separating it from the graywackes below. 
The first systematic classification of American rocks older than 
Carboniferous was presented in 1836 by H. D. Rogers,* who 
placed in two groups the beds between the ‘ fossiliferous sand- 
stone,” (or Oriskany, as we now know it) and the Lower Carbonif- 
erous sandstone ( Vespertine or Pocono of later classifications. ) 
These groups, Nos. VIII and IX of his column were distin- 
guished from the Carboniferous, which he divided into four groups, 
afterwards numbered X, XI, XII and XIII. The same classifica- 
tion, with rather more of detail, was repeated in the Second 
Pennsylvania reportt, as well as in the Second Report of W. B. 
Rogers{ on the survey of Virginia. . 
No distinct effort to subdivide the upper portion of the Devonian 
column of New York was made prior to preparation of the Third 
Report of the Geological Survey. In that report Mr. Conradé 
defines the ‘‘Old Redstone Group (Murchison )” as embracing 
9. Olive sandstone.—Old Red sandstone ? 
8 { Dark-colored shales, 
| Black slate. 
thus carrying it down to the base of the present Hamilton. In 
the same report, James Hall|| introduced the term ‘+ Chemung ”’ 
for gray beds in Chemung county, overlying those of his Ithaca 
group. ; 
The fourth report contains Vanuxem’s description] of the 
series in his district, giving a complete grouping of the higher 
rocks and placing the Montrose or Oneonta sandstone at the top 
of the column. The same report contains the general classifica- 
tion by Prof. Hall** in which the terms, Old Red sandstone, 
Chemung group, Portage group occur in the order given. One 
year later Matherty used the term ‘‘ Catskill Mountain Series ” to 
designate all the rocks of the Catskill mountains from the Lower 
Carboniferous sandstone ( Pocono ) of Rogers down to the base of 
*First Annual Report of State Geologist, Harrisburg, 1836, pp. 12 to 15. 
Second Annual report on the Geological Exploration.of the State of 
Pennsylvania, by H. D. Rogers, Harrisburg, 1838. 
{Second Report of Progress of the Geological Survey of Virginia for 
the year 1857. W. B. Rogers; 1838, pp. 75-80. 
SAssembly Document, No. 275, Albany, 1839, p. 72. 
\|Loc. cit. p. 322. "Assembly Document, No. 50, 1840, p. 381. 
**Loc. cit. pp. 452-453. 
+tAssembly Document, No. 150, 1841, pp. 77-82. 
