Geological Survey. 497 
twenty to thirty miles broad. It is generally from twelve 
to twenty inches thick. 
In aslate rock, which may be called secondary gray- 
wacke, or calciferous slate. Numerous beds of gypsum of 
vast extent. It is found in no other situation in beds; but 
New-York. It is found in geodes, however, in swinestone, 
&c. In this slate we find shell limestone, water limestone, 
epsom salts, copperas, and alum, in numerous localities. 
This rock underlies all the country over which the stage 
road passes from Oneida Creek to near Genesee River; 
parallel to the canal, and from half a mile to twenty miles 
south of it. 
In swinestone, or it may be called geodiferous lime rock. 
This rock abounds in geodes, which contain beautiful 
erystals of sulphate of stroutian, limpid cubic crystals of 
fluor spar, transparent waxy zinc blende, immense quanti- 
ties of dog-tooth spar and pearl spar, selenite and snowy 
distance west of Niagara River. It forms most of Niagara 
Falls. The canal at Lock Port is cut thirty feet deep into 
it for two miles. East of Genesee River it is cut through 
this rock about half a mile. 
In pyritous shale of English Geologists; or it may be 
called pyritiferous rock, as it is not always slaty. ‘Chin 
_ It may be proper to mention, that the sulphuretted hy- 
drogen gas which issues through water at the foot of the 
bank a mile above Niagara Falls, and near the head of 
squago Creek, in Herkimer county, manifestly proceeds 
from pyritous shale. The gas burns with a flame equal in 
€Xtent to that of half a dozen candles, at both places, But 
