314 
GEOLOGY OF THE FOURTH DISTRICT. 
156. 
2. Onondaga and Corniferous limestones. b. Lower spring. 
3. Marcellus shale. 
The upper spring rises near the junction of the Onondaga salt group and the Corniferous 
limestone. The source, however, is much deeper, as it can be penetrated with a rod to the 
depth of fifteen feet or more. The lower spring rises from the same strata, at a lower posi¬ 
tion. There are also in the same neighborhood, at about the same level as the lower spring, 
several others in which the water is strongly impregnated with gas. 
The position of the springs at Manchester, in Ontario county, is precisely similar. 
1. Limestone of the Onondaga salt group. a. Point at which the springs issue. 
2. Onondaga and Corniferous limestones. 
3. Marcellus shale. 
The shale above the limestone does not approach within a mile or more of the edge of that 
rock ; and it can scarcely be supposed to give origin, by the decomposition of its iron pyrites, 
to the gas which rises from the rock below.* 
4. Salines, or Brine Springs. 
The principal brine springs of the Fourth District have been noticed under the head of 
Medina sandstone and the Onondaga salt group. The first have their origin in the red shales 
and marls of the Medina sandstone, extending throughout the whole length of the district, and 
likewise known in Canada in the same rock. In the early settlement of the country, salt was 
manufactured from these springs ; but its quality was often inferior, and highly colored from 
the red marl. The brine is also very impure, from the presence of the chlorides of calcium 
and magnesium. 
Since the supply of brine in Onondaga county is so much more copious, and the facility of 
manufacturing and transporting the salt so much increased, all these springs in the Medina 
The large proportion of iron pyrites in the Marcellus shale, has been supposed by some to give origin to this gas. 
