Review of the New York Geological Reports. 43 ° 
Arr. V.—Review of the New York Geological Reports. 
(Continued from Vol. xtv111, p. 316.) 
In continuation of the New York Geological Reports, we pro- 
ceed with the description of the 
Onondaga Salt Group. (Not recognized in the Pennsylvania 
survey. )—In the geographical subdivisions of the New York 
System adopted by most of the New York geologists, this group 
forms the lowest member of the Helderberg series ;* in the chro- 
nological table, it forms the second member of the middle divis- 
ion in the ascending scale. 
Asa whole it is an immense mass of argillo-calcareous shaly 
rocks, enclosing veins and beds of gypsum; hence this has been 
designated by some as the “ gypseous shales.” From the litho- 
logical character of these beds, their outcrop has suffered much 
from denudation, and their superficial area occupies a wider dis- 
trict of country than most of the preceding members, especially 
along the valley of the Clyde,—covered up from view, however, 
to a great extent, by accumulations of drift. 'T’o the east it runs 
out near Sharon Springs; west it extends into Canada, being co- 
extensive with, and running parallel to the Niagara group, upon 
which it rests. Its superficial area is represented on the geologi- 
cal chart by a light ochre. 
Four divisions have been distinguished in the description of 
the Onondaga salt group, though the lines of separation are by 
no means well defined. 
1. Red and greenish shale below. 
2. Green and red marl, shale and shaly limestone, with some 
veins of 
3. Shaly and compact impure limestone, with shale and marl, 
embracing two ranges of plaster beds, with hopper shaped cavi- 
ties between. 
4. Drab colored impure limestone with fibrous cavities; the 
“Magnesian deposit” of Vanuxem. 
€0 
this is perhaps the more correct grouping, since these formations are in full force 
along the valley of Lake Ontario, and are almost absent in the first geological dis- 
trict, where the Helderberg Mountains are situated. 
