No. 50.] 
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" Calciferous sandrock.^^ This rock is abundant at all the uplifts 
on the Mohawk, and in many parts of the new county of Fulton, for- 
merly the northern part of Montgomery. It is found to the east and 
south of Amsterdam, the Noses, St. Johnsville, Little Falls or Rockton, 
and on the East and West Canada creeks, and on Spruce creek, a tri- 
butary of the former. I did not meet with this rock north of Oneida 
county. At the Noses and Little Falls it rests immediately upon the 
primary, without any intermediate mass, but in other places, those lay- 
ers which correspond with the Potsdam sandstone intervene. 
The " calciferous sandrock," in many localities abounds with cavi- 
ties large and small, often containing rock crystals and small quantities 
of anthracite coal. Frequently the large cavities, which in part are 
filled with crystals, have a covering of coal, which is flattened or de- 
pressed towards the centre, showing that the coal was in a soft or 
yielding state. In other cavities, the coal is sometimes found in the form 
of drops or buttons. These facts show that the coal was once bitumi 
nous, and had by heat been changed to anthracite. In some of the 
cavities the whole of the crystals, amounting to a peck or more, will 
have their angles and edges rounded from friction, either from water 
having entered with a circular motion, or that a motion of the kind had 
originated from either vapour or gas. That this rounding of the angles 
and edges of the crystals was anterior to the solidification of the coaly 
matter, is evident from the fact of the anthracite covering, in the man- 
ner above mentioned, the crystals which had been rounded by rubbing 
one against another. 
At the Noses, Little Falls and Middleville, this rock attains its great- 
est thickness, being about 250 feet thick at Little Falls. 
In the second district the Lingula acuminata characterises the cal- 
ciferous, but I have not seen this fossil in the third district, nor any 
other than the casts mentioned in the second report. 
Fucoidal layers. These layers were separated from the above rock 
from their distinctive characters, position, and finding them in Lewis 
and Jefferson counties, without the " calciferous sandrock" upon which 
they rest. It is in these layers that we first meet with that peculiar 
class of marine organization, in all probability vegetable, which for con- 
venience have received the name of fucoides. In these layers, they 
are evident and abundant, though the forms more or less regular, aris- 
[Assembly No. 50.] 47 
