424 
[Assembly 
There are several quarries between this place and Dansville in which 
it is difficult to find any characteristic fossils. The rocks consist of thick 
layers of sandstone with intervening masses of shale ; and near Dans- 
ville give more marked evidence of the group to which they belong. 
Quarries have been opened on both sides of the valley, where materi- 
als are now obtained for locks, bridges &c. on the Genesee Valley ca- 
nal. The group also affords the finest flagging stones in the district ; 
these are known by the presence of the fucoids already mentioned. 
GENESEE COUNTY. 
In this county we find the rocks of Livingston, with the addition of 
the Onondaga saliferous group on the north, which extends through the 
towns of Bergen, Byron, Elba and Alabama, and into the northern parts 
of Leroy and Stafford. 
The most northern portions of this mass consist of greyish or green- 
ish grey marl, homogeneous in texture, and very compact when first 
exposed, but crumbling rapidly. Thin courses of reddish and chocolate 
colored marl are seen in some places in the northern part of the coun | 
' ty. Farther south and along the centre of these towns it is more grey 
or ash colored, contains thin seams of fibrous gypsum and selenite, 
and occasionally small masses of granular gypsum. This part of the 
mass is exposed only in wells which from the difficulty in obtaining 
water, are often dug to the depth of 70 or 80 feet. The grey marl 
and gypsum is found to contain large seams or joints apparently water 
worn ; these without doubt act as drains and carry off the water from 
above. 
Some wells in this part of the group yield an acid water. One of 
these, belonging to Mr. Gifford, of Bergen, I examined in company 
with the Rev. Mr. Griswold* ; the water is said to contain acid enough 
to curdle milk ; and though not sensible to the taste is considered 
unfit for use. The famed acid spring in Bergen rises from this rock. 
Some of the wells in the immediate vicinity, and in the same formation, 
yield good water. 
A little north of Bergen Centre the greenish marl comes to the sur- 
face, and is excavated for the passage of the rail-road. Two miles 
west of that place the same marl is seen in the roads and in the banks 
* I am particularly indebted to the hospitality and attention of this gentleman, who 
has given much attention to the Geology of the vicinity. 
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