406 
[Assembly 
of shale, which contains the fossils common to the Chemung group, 
with others, the large pecten-like Avicula. The lower portion of the 
mass is a hard grey sandstone, containing, in some parts, great num- 
bers of fossils, among which Delthyris and Leptsena are most abun- 
dant. A species of Orbicula is also very numerous, and a species of 
Pterinea ? noticed only at the transit bridge and at this place. This 
sandstone has been quarried for purposes of building ; it is durable and 
presents a very good appearance. 
About a mile and a half south of Angelica, sandstone has been quar- 
ried, though the greater portion of the rock exposed is shale. The 
sandstone has been used in the construction of a mill near the quarry ; 
portions are at first extremely friable and scarcely cohere. Like most 
sandstones of this region, it contains a large proportion of moisture. 
Van Campen's creek, near Hobbieville, exhibits shale and sandstone 
strata, somewhat similar to those at Angelica, but less abounding in 
fossils. The only peculiar one at this place, is a large Orbicula ; the 
others are of the usual kinds fomid in all the rocks of this region. The 
sandstone along this creek was quarried by Judge Church, and used in 
building more than thirty years since ; it still remains firm, though 
somewhat iron stained from the decomposition of pyrites.* 
At Philipsburgh, two and a half miles south of Hobbieville, we find 
a change in the rocks, which is indicated by their fossils more than 
their lithological character. Green shale is the predominating portion 
of the mass, and with some, thin strata of sandstone occupies the bed 
of the river for an eighth of a mile, and together with the vertical bank, 
presents a thickness of 40 feet or more. The strata dip at a little 
more than 60 feet in the mile, or nearly one degree. The upper stra- 
ta of the mass are sandstone, the lower part of which is concretionary. 
The lower half of the whole mass contains a great number of fossils, 
many of them characteristic of the Chemung group, and several others 
which have not been collected elsewhere. The sandstone containing 
fossils is hard and durable ; this, as well as some of the softer portions, 
has been used in constructing the dam at this place. 
Above Philipsburgh, on the Genesee, rocks similar in character occur 
in several places in the bed and bank of the river. At Vandermark's 
* My acknowledgements are due to Judge Church, as well for his hospitable enter- 
tainment as for many valuable facts regarding the geology and agriculture of Alle- 
gany county. 
