94 GEOLOGY OF THE TfflRD DISTRICT. 



At Whiting quarry in the town of Cicero, there are some geodes lined with rhombic crys- 

 tals of carbonate of lime : Gypsum, in small globuliform accretions, has also been found in 

 some of the other quarries, showing that the same causes have operated in this group as well 

 in the third as in the fourth district ; the geodes especially being so numerous in the latter one. 



The calciferous slate of Prof. Eaton, which underlies the limestone of Niagara, Lockport, 

 Rochester, dec, which is quite a thick mass at Wolcott village, is seen but for a short dis- 

 tance in the third district. At Hyde's quarry near Plainville, it appears there is a dark 

 colored shaly limestone containing Strophomena depressa, Orthis hybrida which somewhat 

 resembles the 0. testudinaria, fragments of the Asaphus caudatus, the Orthis bicostata, and 

 some slender stems of an encrinite which is also found in the group further east. 



12. ONONDAGA SALT GROUP. 

 Calciferous Slate, or Second Greywacke, with Shell Limerock of Eaton. 



This is one of the most important groups of the district, containing all the gypsum masses 

 of western New- York, and furnishing all the salt water of the salines of the counties of Onon- 

 daga and Ca3ruga. The group is coextensive with the district, commencing in the first dis- 

 trict, and extending through the third and fourth districts into Canada. It rests upon the 

 Niagara group, from the middle part of Herkimer county, throughout its whole course west. 

 From the point where the Niagara group terminates at the east, it rests upon the Clinton 

 group ; and as the latter group also comes to its end near the first district, it reposes there 

 upon the Frankfort slate, upon which it continues to near the Hudson river. 



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 

 from thence west the canal was excavated in the group ; the extent of surface on the north 

 side, after a few miles, becomes as great as that on the south side ; the group increasing in 

 breadth on both sides of the canal, in extending itself through the district. The great descent 

 from the high range is due to the dip of the rocks to the southwest, and the rise of the bot- 

 tom of the valley. The extent of surface which the group covers, or which is exposed to the 

 west of Oneida, was owing to its forming a part of the great level, whose rocks escaped that 

 destruction which befel the same rocks to the east ; and those masses which covered the rocks 

 of the great level, shared the fate of tlie rocks of the level, at the east. That such was the 

 fact, appears evident from the range of the Helderberg division, which extends along an east 

 and west line ; the Onondaga salt group projecting beyond that line to the north for some 

 miles, through the three terminal counties of the district. The high east and west ranges of 



