Luthek — -Economic Geology of Onondaga County. 



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grey or pink, weathering white and containing, especially toward the bottom 

 of the beds, impressions of great numbers of Spirifer arenosus and associated 

 fossils. 



The greatest thickness observed in this county was eighteen feet at this 

 place. Good exposures occur a mile or two northeast, and in the vicinity 

 of the road leading from Skaneateles to Elbridge. Vanuxem states its 

 thickness here to be thirty feet. Fragments, large and small, easily recognized 

 as from this bed, are found scattered over the fields clear to the south line of 

 the county. Mr. Graham says that in the Tully salt wells the Oriskany sand- 

 stone is fifteen to eighteen feet thick, light-colored, coarse and gritty, wearing 

 away the corners of the drills so that they "get out of gage' 1 and make a 

 smaller hole. 



The economic value of the Oriskany sandstone to this county is not great. 

 It was quarried in the town of Skaneateles and used in the construction of 

 the lock on the Erie canal at Jordan, also for cellar and foundation stone, and 

 occasionally for lining in lime kilns. The proximity of the Onondaga lime- 

 stone which can be worked much more cheaply appears to be the main cause 

 of its disuse. 



Upper Helderberg Group. 



The strata of this formation are represented in this county by a bed of 

 light grey, glistening, semi-crystalline limestone, separated by thin seams of 

 carbonaceous shales into layers from an inch to two feet, six inches thick, 

 and which maintain their character and thickness over large areas. Many of 

 these layers are compact and composed almost entirely of calcic carbonate, 

 but others, and they are not confined to any particular horizon, are shaly 

 and contain more or less argillaceous matter. Both the compact and the 

 shaly layers contain fossils in great abundance, especially corals and crinoids. 

 Many species of brachiopods and gasteropoda are common everywhere in the 

 beds. Flattened nodules of dark bluish black chert or hornstone, some- 

 times m continuous layers, also occur throughout the entire mass, though 

 more common in the upper part. 



At Manlius, in Alvord's and Hinsdell's quarries, a layer of chert occurs 

 in the stratum of limestone superjacent to the Oriskany sandstone: also 

 in the lower layers at the Reservation quarry, and at every exposure of 

 the Onondaga limestone as the lower part of the formation is frequently 

 called, as well as in the upper part to which the name Corniferous w as given 

 on account of the presence of the hornstone. The rocks of this epoch have 



