546 



NEW YORK STATE MUSEUM 



" It forms a part of the high range on the south side of the 

 Mohawk ; appearing at the north end of Otsego county, and in 

 Herkimer and Oneida, being its northern outcrop. It makes its 

 first appearance by the side of the Erie canal at the east end of 

 Madison county, and thence west the canal was excavated in the 

 group. 



" The Onondaga salt group may be divided into four deposits. 

 There are no well-defined lines of division between the deposits ; 

 but for practical purposes the divisions are sufficiently obvious. 



" The first or lowest deposit is the red shale, showing green 

 spots at the upper part of the mass. *2d. The lower gypseous 

 shales, the lower part alternating with the red shale, which ceases 

 with this mass. 3d. The gypseous deposit, which embraces the 

 great masses quarried for plaster, consisting of two ranges, 

 between which are the hopper-shaped cavities, the vermicular 

 limerock of Eaton, and other porous rocks. 4th and lastly. 

 Those rocks which show groups of needle-form cavities placed 

 side by side, caused by the crystallization of sulphate of magnesia* 

 and which may from that circumstance be called the magnesian 

 deposit. 



'•The whole of these deposits are found between Oneida creek 

 and Cayuga lake. To the east of the creek, they do not all 

 occur, as will subsequently be made known. They thin out to 

 the eastward and probably terminate entirely a few miles east 

 of the Hudson river ; from which point their thickness gradually 

 increases toward the west, and reaches its maximum in the 

 counties of Onondaga and Cayuga, where it is not less than 

 700 feet. The gypsum has not been seen east of the western 

 part of Oneida county. The red shale comes to its end at the 

 east end of Herkimer count\^ ; and the whole group is reduced, 

 in the Helderberg in Albany county to a few feet of light-gray 

 or lavender-colored compact calcareous rock with pyrites, 

 separating the Frankfort portion of the Hudson River group 

 from the water lime series." 



The outcrop of the Salina shales is shown on the accompanying 

 map. 



The red shale is fine grained, earthy in fracture and without 

 regular lines of division. It breaks or crumbles into irregular 

 fragments. This deposit is not found east of Herkimer county 



* 8ulphate of lime most probably. 



