No. 50.] 
375 
reous shales, whilst the lower will embrace the green shales, their as- 
sociated sandstones and iron ore beds. 
This group extends through the third district, forming a part of the 
high range south of the Erie canal in Montgomery, Herkimer and Oneida 
counties. By the dip of the rock to the southwest, the rise of the ground, 
and from the extent of denudation when upon the summit level of the ca- 
nal, this group ceases to form a part of the elevation, but underlies the 
southern part of the level, extending through Lake Oneida, and onwards 
in the direction of the Lake to the fourth district. This group is an highly 
important one for its iron ore, limestone, sandstone, and from its form- 
ing an era in marine botany, for the number and kinds of plants which 
are found in it. 
Its fossils, in the upper or calcareous part of the group, are Orthis 
bicostata, Delthyris lineatus, Strophomena rugosa, and a few others. 
From the thinning out of this part of the third district, it contains but 
few fossils comparatively with the same mass in Mr. Hall's district, 
where it is of great thickness. In the lower part they are more nume- 
rous, but a few only have been determined. The small and peculiar 
crustacean, the Agnostus pisiformis belongs to this part, being found 
with the iron ores. So also the Pentamerus elongatus, Strophomena 
rugosa likewise, being the lowest position of the shell. With these we 
have the Trimerus delphinocephalus and two other Trilobites not deter- 
mined. 
The greatest thickness of this group must be over 200 feet. In this 
group we have the third deposit of iron ore, viz. the oolitic or concre- 
tionary red oxide. 
Onondaga salt g7^oup. This is not only an immense deposit, but an 
highly important group, extending through the third and fourth districts, 
with a thickness in Onondaga of about 700 feet. It embraces all the 
salines of Onondaga and Cayuga, as well as all the Gypsum beds of 
the State. No'gypsum or plaster of any consequence has been found 
east of Oneida creek, excepting in the town of Stark, south of Little- 
Falls, and this accords with the greatest development of the group 
which is west of that creek. 
It is divided into four parts or masses. " The first or lowest is the 
Red shale. Second, the lower Gypseous shales, the lower part alterna- 
ting with the red shale, the red ceasing entirely with this mass. 3d the 
