104 GEOLOGY OF THE THIRD DISTRICT. 



C(Hnmon to its layers when hard or solid, to form an arch oyer the gypsum, which, though not 

 regular, is yet well defined. Where this exists, the mass or rock which forms the arch is 

 full of cracks, owing to the force exerted by the plaster in its expansion upwards, and shows 

 more or less consolidation of that part before the particles of plaster had collected together, 

 and assumed the form in which we find them. Where the mass which encloses the gypsum 

 is soft or friable, no arching appears, owing no doubt to the particles of the one taking the 

 place of the other, both being in a yielding state. 



No. 2, is light-colored, like No. 3, with hopper cavities ; two feet thick. 



No. 3. Thicker layers than No. 4, harder, not so dark colored, with hoppers ; and at its 

 intersection with the same, it is porous like the lower vermicular rock : four feet. 



No. 4. Thin layers, brownish, with a few pores or cells, the whole appearing to be altered 

 or decomposed : three feet. 



No. 5. Slaty, variegated, grey and blue, striped, etc., with some fossils consisting of fucoids ? 

 resembling small spear-grass ; they are charred, or in other words of a black color from coal 

 or carbon : also the Lingula limosa, and two or three yet undescribed thin bivalve shells, whose 

 character is very obscure, and which are of interest only from their rareness and position. 

 Total thickness of this part, about ten feet. 



No. 6. Porous bluish limestone rock (vermicular), the pores or cells larger than usual, and 

 slightly compressed ; these cells show that their origin is due to saline or solid, and not to 

 gaseous matter as before stated : three feet thick. This terminates the mass, the third or 

 upper alluvion of Chittenango covering the whole. 



Not far from Bull's quarry is Mr. Brown's, about a mile and a quarter from Clockville, on 

 the top of a low hill : the gypsum is very near the surface, and therefore more advantageously 

 quarried. It presents a range of detached masses more or less rounded at the top, and with 

 a flat surface below, enclosed in the usual thin layers of dark brownish and apparently a much 

 altered rock. Above the gypsum are the layers No. 2 and 3 of Bull's quarry, with hoppers 

 and pores. 



The old Sullivan bed, now not worked, and near the turnpike gate, was the first plaster 

 mass that was discovered. It no doubt contains all the members at Bull's, though not so 

 prominently developed : it was the first one examined. The lower part is about twenty feet 

 thick, being the part where the gypsum was quarried, none of it having been removed when 

 visited. Above this was the mass which corresponds with No. 5 of Bull's quarry ; then a 

 bed of an olive color, much altered, two feet thick ; upon which is the vermicular rock, about 

 three feet thick, the pores large and numerous. In a quarry further east, the pores are both 

 large and small. 



The plaster hills range from east to west through the county, extending south of the turn- 

 pike from two to four miles. The hills are more or less round and short, rendering some 

 portions of their plaster very accessible, the layers in which the masses exist having but a 

 shght inclination. These latter observations apply also to the counties of Onondaga and 

 Cayuga. 



In Onondaga county, numerous quarries are opened along its whole range to the south of 



