412 
[Assembly 
CATTARAUGUS. 
The general surface of Cattaraugus county maintains about the same 
elevation as Allegany ; the Genesee in the former, and the Alle- 
gany river in the latter, also take their rise in about the same altitude, 
and continue their course v^ith nearly the same descent, though flowing 
in nearly opposite directions. Although this county is crossed by nu- 
merous streams of considerable size, still there are few situations where 
a good view of the rocks can be obtained. The valley of Ischua creek, 
which extends nearly across the county from north to south on its east- 
ern side, exposes the strata only in a few places. The Cattaraugus 
creek pursues its course the whole distance in the outcrop of the strata, 
consequently developing but one or two rocks. 
The rocks of this county are a continuation of the same gi'oups no- 
ticed in Allegany county. The Gardeau and Portage groups form the 
northern boundary of the county, and are exposed along the Cattarau- 
gus creek. These are succeeded by the same shales and sandstones as 
before noticed in Allegany, There appears, however, a general dimi- 
nution in thickness of all the masses to the westward ; and many 
which in Allegany are of great thickness, appear here much diminished. 
This must necessarily be the fact, since all the upper groups thin out 
partially or entirely before reaching the State of Ohio, where the lower 
limestones are brought into the immediate vicinity of of the coal mea- 
sures. When the examinations in Chautauque county are completed, 
we shall be able to present some more correct data regarding the rate 
at which these rocks diminish in thickness going west. 
Notwithstanding that the rocks are exposed at few places, still from 
the great elevation of the country and the thinness of alluvium, they 
are found at moderate depths below the surface. On the south branch 
of the Cattaraugus creek, there are several points where rocks are ex- 
posed, but there are no deep excavations. In the southwest part of 
Freedom, on lot No. 19, there are several courses of sandstone and 
shale, exposed in a deep ravine, along which the road winds. Some 
of the sandstone courses are two or three feet thick, others but a few 
inches. It is quarried for grindstones, being of the same quality as the 
Rushford giindstone rock, and in fact is a continuation of the same 
mass. The strata above the grindstrone rock, are characterized by the 
peculiar fucoid so abundant in the same rocks on the Caneadea. In some 
of the sandstone courses there are numerous small nodules of shale, which 
