No. 200. 
S67 
The greater part of the county between the primary mass north, and 
the Mohawk south, is covered with black shale ; the chief cause of the 
favorableness of that part of the county for dairy farming, the shale 
producing by decomposition a highly favorable if not the best of grass 
soil. To this advantage, there is added a fine southern slope, and that 
moderate temperature in the summer season, which is required for first 
rate dairies, as to quality, either of cheese or butter. 
South of the Mohawk from Oneida county, the black shale extends 
along the course of the river, interrupted by the uplift of Little-Falls, 
over which, at the southern end, it passes, and connects itself with the 
mass below, through which the uplift had been protruded. From thence 
it continues along the river, meeting but one more uplift near the coun- 
ty line, the prolongation of the East Canada, 
The black shale, both north and south of the Mohawk, is usually ac- 
companied by thin layers of very impure compact limestone, in which 
it differs from the next mass which succeeds to it, the green shale which 
has, on the contrary, thin layers of sandstone or rubblestone, the same 
rock which covers the black shale to the south of Montgomery county. 
There two- shales form the surface which lies between the river and the 
elevation which bounds the valley to the south, though the greater part 
of both is covered with alluvial. 
Millstone Grit of Professor Eaton. — Immediately on the green shale, 
without any connection other than support, reposes this quartz conglo- 
merate, a rock of some interest, being the first one met with made up 
of rolled stones or pebbles. They are of vitrous quartz. This rock 
extends throughout Herkimer and Oneida, with a thickness of thirty or 
more feet. As this rock was not laid down in any of the common sys- 
tems of geology, it was considered by Prof. Eaton as identical with a 
similar rock, as to composition, forming a member of the coal series, 
and called by the English geologists the millstone grit. From the brine 
springs of New- York being above this quartz conglomerate, and the po- 
sition of many of the important salines of Europe being above the coal 
of that continent, that of Cheshire being a noted instance, gave rise to 
a coincidence in analogy which readily identified them. 
The lower part of the conglomerate is almost invariably highly char- 
ged with sulphuret of iron or pyrites, the part containing it usually from 
five to six inches in thickness. By the action of the air, the pyrites is 
changed to copperas. In some localities, where the shale has under- 
gone decomposition simultaneously with the change in the pyrites, both 
