Review of the New York Geological Reports. A5 
takes, in part, of the character of serpentine, and, in part, that of 
granite and sienite, whilst some of the adjacent calcareous por- 
tions show a crystalline grain with streaks of a light bluish shale. 
These metamorphic products he conceives were not formed by 
a “dry heat or fire,” but were the result of solution and crystal- 
lization from a thermal water. 
We would inquire, is there unequivocal evidence that the met- 
amorphic rocks are entirely cut off from all connection with in- 
ferior intrusive veins ?—because, unless there is, we can perceive 
no good reason for denying to them an origin which is generally 
conceded to belong to geological formations of similar structure. 
A microscopic, crystalline texture is certainly not incompatible 
with fluidity or semi-fluidity by dry heat. Is it not rather evi- 
dence of sudden consolidation ? 
The thickness of the first division of the Onondaga salt group 
on Steele’s Creek, is estimated at eighty feet, but in Onondaga 
County its maximum is five hundred feet, unproductive of any 
valuable mineral. 'The exact thickness of the other divisions 
does not appear to have been ascertained, probably for the want 
of favorable sections. We are informed, however, that a well 
had been sunk at the Indian Reservation to the south of Vernon 
Village, eighty feet through strata belonging to the second divis- 
ion ; these borings were commenced below the range of the plas- 
ter beds. Some of the plaster quarries in the third division have 
exposed from twenty to sixty feet of strata above the gypsum 
deposite. In Madison County the upper and lower porous or ver- 
micular limestones are together twenty four feet. In the middle 
counties the entire thickness of the Onondaga salt group must be 
from six hundred to a thousand feet.* 
Notwithstanding its great thickness, this formation is very bar- 
ren in fossils. The corals and shells of the Niagara group sud- 
denly ceased to exist, perhaps, as Han suggests, being over- 
whelmed by the sudden outbreak of a mud volcano at the bottom 
of the ocean, by which the waters became surcharged, not only 
with argillaceous sediment, but became contaminated either with 
free sulphuric acid, or sulphate of magnesia and soda. 
* Haut, at p. 133 of the Report of the Fourth District, speaking of the immense 
accumulation of mud on the top of the Niagara limestone as caused by a mud vol- 
cano, estimates it at a thousand feet. 
