466 
[Assembly 
between the third and fourth districts. And there is also an equally 
obvious increase in thickness of some others of the groups. The thin- 
ning out, however, prevails over the expansion, so that the whole body 
of rocks in Cattaraugus, above the Moscow Shales, and below the con- 
glomeratCj is much less than it is as far east as Painted Post. 
The shales observable between Ithaca and the termination of the 
black shales a few miles down the Cayuga lake, are developed farther 
west, and particularly along the Cattaraugus creek, upon a grand scale. 
While the Ithaca group, immediately succeeding, is almost entirely 
wanting. 
Of the groups above, only the most imperfect sections were seen, 
but all the geological features of the county taken together, clearly in- 
dicate a reduction in their thickness. 
Beside these groups, there are two which deserve particular mention 
in a notice of the rocks of this county : the Ischua Sandstones and the 
Conglomerate. 
The Ischua Sandstones^ of which a description is given under the 
head of quarries^ are developed in Allegany county in a few localities. 
Numbers of large rectangular masses are found in the valley of Wig- 
wam creek, which point to the ledge somewhere in the vicinity, though 
perhaps buried below the soil. In place, they were seen in the bed of 
a small stream emptying into Black creek from the west, about ten 
miles from Angelica. Its farther extension west, than the region of 
Machias, has not been ascertained. 
The Co7iglomerate is the highest rock in the series that has yet been 
observed in the State. Immense blocks of it are found at Chipmuck 
ripple, on the Allegany river, and near Judge Wright's, southeast of 
Ellicottville. Also between Napoli and Little valley, on the James- 
town and Ellicottville stage road, near Judge Leavenworth's, and at 
numbers of other localities. But the places where it is seen in ledges 
are comparatively few, and only upon the very highest points of land. 
One, south of Olean five miles ; two between Great valley and Little 
valley, and several south of the Allegany, comprise all in this county 
concerning which information was obtained. 
The locality most visited, is about seven miles south of Elhcottville, 
and one and a half west of Great valley post office. It is known as 
