28 
GEOLOGY OF THE THIRD DISTRICT. 
]. POTSDAM SANDSTONE. 
Potsdam and Keeseville Sandstone. 
(No. 1 . Pennsylvania Survey.) 
This name is applied by Dr. Emmons to an important rock for thickness, extent, and for 
economical purposes, which exists in the Second District, being the first mass going north 
towards Lake Champlain, and further west, which rests upon the primary, the calciferous 
sandrock being the next rock as to age ; and when together, they rest upon the sandstone. It 
appears to form two distinct varieties in that district, one of which is found at Potsdam, the 
other at Keeseville. This rock corresponds in position, etc. with No. 1 of the Survey of 
Pennsylvania, and is common to New-Jersey, but in both these States it resembles the 
Keeseville and not the Potsdam variety. 
In the third district this rock is rather rare, and confined chiefly to the northeastern part 
of Lewis county, unless from change of character it is confounded with the calciferous sand- 
rock. It presents two varieties in Lewis county, the locality not far from Lewisburg fur¬ 
nace : a conglomerate of quartz, the fragments chiefly angular, with a few other fragments 
of primary rock, forming the lower part of the mass ; and a sandstone above, exhibiting the 
same characters in all respects as at Potsdam, being in very regular horizontal layers or 
courses, from an inch to a foot or more in thickness, striped, of a reddish and yellowish 
color, and of rather a coarse and loose texture. The sandstone appears in a few low insu¬ 
lated ridges about two miles from the furnace, and also near Harrisville. 
Towards the Mohawk, the sandstone is found on the west side of Klipp hill, or the north 
prolongation of the Noses, extending from the turnpike which goes to Johnstown, for about a 
mile and a half towards the south road. Numerous small patches there exist, some of which 
are composed of two layers : one hard and whitish, the other friable, and colored brown and 
red. They rest upon the primary rock in the usual unconformable manner, and were, no 
doubt, once parts of a continuous mass destroyed with the former overlying rocks. 
The layers which occur between the primary rock and the calciferous, at the paper-mill on 
Spruce creek, may be refered to this rock. There the characters are somewhat different, 
though the material is in a great measure the same, being a coarse grey rock, resembling in 
parts, at first sight, a recomposed granite ; that is, a granite whose mineral constituents had 
been separated and re-united again, without much if any change of place. The first layer is 
about six inches thick, and contains fragments of vitreous quartz, which are likewise found in 
some of the layers a few feet above. 
At the base of the well characterized calciferous mass on the Mohawk, below Canajoharie, 
and on West Canada creek, below Middleville, etc. there are a number of extremely hard 
compact layers, whose fracture shows a glistening grain, as if composed of sand united by a 
siliceous cement, as if the particles had come together by a partial softening and pressure. 
