No. 50.] 
399 
From the village of Dansville, south, we find the same succession 
of rocks. The lower Fucoidal group is well exposed along the Cana^ 
seraga creek for six miles south of Dansville. The sandstone layers 
containing the fucoids are hard and furnish excellent flagging stones. 
South and above the latter, we find the upper Fucoidal group ; visible 
at intervals along the road to Arkport ; and at Whitney's falls, just with- 
in the line of Alleghany county, a portion of this group, more than 
100 feet thick may be seen, with the peculiar fucoid penetrating the 
strata vertically. 
One mile west of Arkport, where the Canisteo river comes into the val- 
ley from the west, appears the first evidence of a change from the Fucoi* 
dal groups below, to the Chemung group above. This is, by the presence 
of a small coralline (Aulopora ?) which is found abundantly in the Che- 
mung group further east. In following the valley of Canisteo from this 
point, the descent nearly corresponds with the dip of the strata ; conse- 
quently^we observe few changes, and none but the lower rocks of the Che- 
mung group are visible before coming to the mouth of Bennett's creek. 
Along this creek, sections of rocks appear at intervals, and consist, as 
the others, of sandstone and shale, each in turn predominating, though 
more generally the shale. Five miles from the Canisteo, on Bennett's 
creek, there is a thick mass of sandstone, overlaid by calcareous sand- 
stone, containing abundance of fossils of Leptsena and Delthyris. The 
stone is very firm and durable and easily quarried, in blocks of neces- 
sary size for building ; and the part containing fossils is much used as a 
fire stone, in the backs and sides of fireplaces, ovens, &;c. 
Nine miles from the Canisteo, at La Grange, in the town of Green- 
wood, the rocks are seen both along Bennett's and Rigg's creeks; and at 
the point of land near their junction are several strata of sandstone, proper 
for grindstones. The whole thickness is from eight to ten feet, and the 
layers from two to eight inches. Seven hundred dollars worth of grind- 
stones have been obtained from this quarry in one year, and only fifty feet 
of the courses opened ; and should the demand warrant it, the supply might 
be increased ten fold.* In ascending Rigg's creek, these strata disappear 
beneath the surface, and are succeeded by greenish shale, with thin lay- 
ers of silico-calcareous rock with fossils. This shale contains iron py- 
rites and decomposes rapidly. The grindstone strata are visible on 
* This quarry belongs to Mr. Benjamin F. Brundage, to whose kindness and hospi- 
tality I am indebted for facilities in examining the rocks of this vicinity. 
