No. 50.] 
405 
In^the western part of Rushford, the sandstone, No, 1 , of the section, 
is extensively used for cellars, walls and foundations. The stone is 
^ here taken from the loose masses that lie on the surface, particularly 
on the northern slopes of the hills. Portions of these masses present 
a slightly conglomerated appearance ; the pebbles generally do not ex- 
ceed the size of a pea, and many times the mass consists of rounded 
grains of sand not larger than a mustard seed. 
Rocks similar to the last, but none of the same strata, are seen in 
Black creek, Crawford's creek and White creek. In the banks of 
Black creek, at Rockville, some thick masses of sandstone alternate 
with green shale, which is slightly calcareous and contains abundance 
of fossils. The most numerous of these is of a mytiloid shape. Two 
of the sandstone masses are about six feet thick each, and divided into 
courses of from two to three feet. They are quarried, for use on the ca- 
nal, under the direction of Judge Chamberlayne and Mr. Dimock. This 
sandstone contains a large proportion of moisture, and requires to be 
quarried and dried before exposed to frost, otherwise it is liable to 
crack. 
Similar sandstone is quarried half a mile southwest, on the line of 
the canal ; it contains fossils of Orthis and Delthyris ; and a mile and 
a half south, and 60 feet higher than the last, a sandstone is exposed 
on the bank of a small stream. The layers are thin, but extremely si- 
hceous and durable. 
The rocks at Rockville are all highly bituminous, the sandstone so 
much so that it scents the clothes of the workmen ; and the water of 
the springs, though clear, has the taste of bitumen. 
Southeast of Rockville, on White creek, we find a greenish shale, 
with a concretionary sandstone, which in some places becomes a con- 
glomerate in the upper part of the layers. When not concretionary it 
is fit for grindstones. Sandstone appears in nearly all the ravines in 
this neighborhood. 
The bed of the Genesee river, at the Transit bridge, is in a mass 
of very fossiliferous sandstone, some portions of which are slightly 
conglomerated. 
At Hull's mills, near Angelica, the rocks are exposed in the bank 
of the creek, for 50 feet or more in height. They consist principally 
