470 
GEOLOGY OF THE FOURTH DISTRICT. 
Thus far no excavations have been made in search of plaster ; and in digging wells, I am 
not aware that it has been seen. Neither is it probable that such would be the case; for I 
am informed, that soon after coming to the rock, water is found ; and the object of search thus 
obtained, nothing else is thought of. Should the value of plaster increase with the exhaustion 
of the beds farther east, we may then expect that search will be made for it in this region ; 
and when the price is such as to repay its being raised from fifteen to thirty feet below the 
surface, we shall in all probability find a sufficient supply in this county for a long period. 
The surface of the country north of the terrace is level, or gently undulating; the inequali¬ 
ties are caused by the accumulation of gravel or sandy loam, the latter often covering gravel. 
The soil for the most part is loamy, of a yellowish or brownish color. A few inches of the 
surface is usually blackened by vegetable matter; sometimes the loam becomes stiff, from 
admixture of clay, and at other times it is mixed with fine gravel. In the lowest grounds the 
soil is clayey; often a stiff white or bluish-white clay, frequently stained with iron, at the 
depth of six or eight inches. On this kind of soil we find evergreens. The clay or soil, in 
such cases, seems to have been deprived of its coloring matter, which is iron, by the percolation 
of water through the carbonaceous matter above. This solution and removal of the iron by the 
carbonated water gives rise to the small beds of bog ore, so frequent in this valley. Where 
the rock is near the surface, or the soil contains much lime, this also is dissolved, and we 
have a deposit of tufa, charged with iron. Several of these beds have been met with, and one 
of them, north of Clarence-hollow, was formerly supposed to be valuable. There is not, 
however, sufficient iron to be of any importance, and the tufa is of no other use than for 
burning into lime. 
From the generally even surface of this tract, we find numerous swamps, of small extent; 
in these are valuable deposits of muck, which will always be available as a fertilizer of the 
soil, more particularly the clayey portions, which require vegetable matter to render them 
lighter and easily worked, as well as more productive. 
The hydraulic limestone follows the course of the terrace, lying at its base, or outcropping 
along the northern slope. It is characterized here, as elsewhere, by numerous and copious 
sulphur springs. These are generally to be found near the base of the terrace, or within a 
mile to the north. Near the eastern edge of the county, this limestone is developed in its 
entire thickness at the falls at Falkirk. The upper portions are extensively quarried and 
burned for cement. It possesses all the essential characters of that from Onondaga and 
Williamsville. The outcrop of the mass may be traced from hence westward, along the slope 
of the terrace. At Clarence-hollow it has been quarried and used in building. At Williams¬ 
ville, it is extensively quarried by J. S. King & Co., and burned into water cement. There is 
made at this place annually from forty to fifty thousand bushels, or ten to twelve thousand 
barrels. About three feet of the upper part are unfit for burning, being too calcareous ; below 
this there are four feet of good quality, and then a shaly mass of two or three feet thickness, 
below which the rock is fit for cement. The facilities for quarrying and grinding the cement 
are here very great, the Ellicott creek descending from the summit of the terrace at this 
