ERIE COUNTY. 
469 
poor, hard soil, too compact for vegetable growth, his lands include a muck swamp, which 
is considered nearly worthless. Now, by ditching this swamp, and carrying its contents into 
his fields, both are essentially improved. The soil of these swamps, when reclaimed, is supe¬ 
rior to the higher grounds. 
ERIE COUNTY. 
The lowest rocks of this county are those of the Onondaga salt group, which are succeeded 
by the hydraulic limestone, the Onondaga and Corniferous limestones. The central part of 
the county is occupied by the Marcellus shale and Hamilton group, while the rising ground to 
the south is formed of the rocks of the Portage group. 
The Onondaga salt group occupies all that low ground on the north of the limestone terrace, 
which is generally designated Tonawanda swamp. The greater part of this portion of country 
is, however, very far from being a swamp, and at present the term may be applied only to 
that portion bordering the creek. Even here, too, its necessary condition is not a swamp, but 
requires only proper drainage to convert it into excellent agricultural land. 
From the ancient condition of this part of the county, and the deep deposit of drift, the 
rocks appear but in a few places, and these only for a small extent. The principal place is 
in the bed of a stream on the farm of Mr. Martin, in the north part of Clarence. 
The rock seen here is that portion containing small cavities of the size of flax seeds, often 
running together, forming linear ones ; and in a few cases, the hopper-shaped cavities were 
observed, though the rock is usually quite solid and firm. Where the rock is penetrated beyond 
the influence of the weather, these cavities are filled with plaster. The portion of the mass 
here exposed is concretionary. No plaster, or even any evidence of it, appears at this place ; 
the mass in question, however, is apparently that which has before been found, separating the 
upper from the next lower course of gypsum beds. 
The shaly and marly portions of the group are met with in digging wells, generally from 
ten to twenty feet below the surface ; in some places they are not found at all, and it becomes 
quite difficult to obtain water at the ordinary depth of wells. 
From this fact we perceive, that a search for plaster, however successful as to the discovery, 
would be of little benefit, owing to the great depth below the surface, which would not allow 
of its being raised at the present prices. That the plaster exists, is very probable ; for there is 
nothing in the character of the rocks, or of the plaster in the western part of Genesee county, 
which indicates that it disappears farther west. Plaster is also obtained on the Grand river in 
Upper Canada, forty miles west of the Niagara. A great portion at least of the intermediate 
space between the two rivers is in a similar condition to the country along the Tonawanda 
creek. 
