There are many small hills scattered throughout this 
part of the county, which deserve a word of mention. On 
account of their form, some of these have become linked 
in the popular mind with the works of the ancient mound- 
builders. A study of their structure and composition, 
however, will readily show that they are collections of 
material that was probably gathered together and left in 
heaps by whirlpools existing in the great interior sea that 
once covered this part of the country. Some of them 
show evidences of being hills of circumdenudation. 
The Red Shales are extensively used in the manufac- 
ture of brick. Further than this they have no economic 
value. 
The Upper Group, or Green Shales.—These might 
more truly be designated the gypseous shales, for their 
color is not a green throughout; furthermore, there are 
some layers of green among the Red Shales, and parts of 
the Clinton Group are also known by that name. 
The group is mainly composed of clayey shales, which 
are, as arule, quite calcareous. There are also some lay- 
ers of magnesian limestone. The group varies in thick- 
ness from 500 to 700 feet, and, together with the red shales 
of the Lower Group, makes a maximum thickness of 1,000 
teet for the entire period. 
Several interesting deposits are found in this group, 
some of which we will now consider. The first forma- 
tions which we will find are the gypsum and plaster beds. 
They occur throughout the entire extent of this group. 
The plaster rock, which is merely the ordinary name for 
the gypsum bearing shales, is quarried in large quantities, 
and used extensively as a fertilizer. Immense beds have 
been opened up in Camillus, Marcellus and Dewitt, and 
large quantities have been taken out andexported. Neither 
are the towns of Manlius, Onondaga and Elbridge lacking 
in this commodity. 
T5 
