450 
GEOLOGY OF THE FOURTH DISTRICT. 
soil for some distance along the road is of a deep red color., owing to the proximity of the 
red shale : farther west the line of this rock is covered by deep alluvium, which in many 
places is colored by the red shale. 
The quarries below Seneca-falls are extensively wrought, and large quantities of the plaster 
sent westward on the Erie canal, and southward up the Seneca lake, and thence by the Che¬ 
mung canal; it is thus distributed over the counties of Chemung and Steuben. The quantity 
of plaster annually taken from these beds is about five or six thousand tons. A small propor¬ 
tion only of the vast quantity has been removed, and, at the present rate of consumption, it 
will be long before these beds are exhausted. 
That portion of the county south of the outlet and north of the turnpike leading to Cayuga 
bridge, is probably underlaid by piaster, and the working of the beds on that side of the 
outlet will gradually lead to its development. 
Above the gypsum, at this place, is a compact marl, containing small masses of granular 
gypsum or selenite, which often appear to have crystallized in the fissures and seams. The 
action of crystallization in this case appears to have taken place after the rock had become 
partially indurated ; and the indurated part of the marl in many places is filled with irregular 
cavities, lined with crystalline carbonate of lime. This appearance may have occurred from 
the rock having been broken up after partial induration, and thus forming with the gypsum, 
then in solution, a kind of conglomerate, as is seen in some rocks below this. 
The soft gypseous marl, surrounding the beds of gypsum, could be very advantageously 
employed on the sandy soils north of Seneca-falls, and west, towards Waterloo. The argil¬ 
laceous matter of the marl would form with the sand a soil of proper consistence; while the 
calcareous matter, and the small admixture of plaster, thus introduced, would be efficient in 
promoting vegetation. 
On Black brook, three miles north of Seneca-falls, this mineral was obtained many years 
since, but it has not been farther explored. At another point in the same neighborhood, a bed 
was found in digging a well, thirty feet below the surface. This depth, however, will effect¬ 
ually preclude any explorations for the mineral while it bears no higher prices than at present. 
On the south side of the outlet, the beds probably continue an unlimited distance; but the 
increasing depth of the superincumbent materials, from the dip in that direction, will effectually 
preclude its exploration at this place. 
Along the south side of the Seneca outlet, the Corniferous limestone occupies a belt of 
country about two or three miles wide, gradually approaching the stream about a mile west 
of Waterloo village. 
Along the area where this rock is exposed, there is evidence of several downheaves ; pro¬ 
bably caused by the solution and removal of the soft rocks below. These downheaves are 
connected with, or produced by the same cause as those more important ones on the east side 
of Cayuga lake, described by Mr. Vanuxem. No manifestation of disturbance appears on 
the surface; the limestone is scarcely raised above the level of the surrounding country, and 
the strata observed in the quarries all dip south at an angle of from four to six degrees 
