THE GEOLOGY OF THE SYRACUSE QUADRANGLE 21 



The prevailing color of the Oriskany is a light gray, generally 

 with a yellowish stain from the hydrous iron oxid. In two places 

 in the Syracuse region it has a reddish tint from the small admix- 

 ture of red hematite. In a few places it contains some pyrite crys- 

 tals which on the weathered surface have oxidized to the yellowish 

 brown oxid. 



In nearly every exposure where there is any appreciable thickness 

 of the Oriskany, it contains black nodules of calcium phosphate, 

 nodules varying from a fraction of an inch to several inches in 

 diameter. These phosphate nodules characterize the Oriskany in 

 many other localities and in some places through the Alleghany 

 ranges in Pennsylvania the nodules are quarried for use as 

 fertilizer. 1 



In many of the exposures the rock is fossiliferous, characterized 

 by the number of individuals rather than by number of species. 

 The fossils are largely brachiopods, Spirifer arenosus, 

 Rensselaeria ovoides and Orthis hipparionyx, 

 in which the calcium carbonate of the shells has been leached out by 

 the ground waters, leaving the large casts which makes the rock very 

 porous. Thus where the rock is below the water table and has any 

 appreciable thickness, it makes an excellent water reservoir. 



The Oriskany sandstone varies in thickness from a small fraction 

 of an inch to about 12 feet in the Syracuse region. It increases in 

 thickness to the east and south, reaching a thickness of about 700 

 feet in central Pennsylvania. The thickest exposure in this vicinity 

 is on the hill above Rockwell springs, on the east side of the Onon- 

 daga valley, a mile northeast of Onondaga Castle, where it is 12 

 feet thick, consisting in part of thin bedded reddish sandstone. On 

 the west side of the valley above Kimber spring it is 4 feet thick. 

 Westward from the Onondaga valley it thins out rapidly, disappear- 

 ing on the west margin of the sheet, to reappear again farther west. 

 At the Split Rock quarries it is a mere fraction of an inch in thick- 

 ness, and a mile east of the quarries it does not occur at all. In 

 Russell's quarry at East Onondaga, it is about 2 feet thick ; at Brit- 

 ton's quarry a half mile northeast, it is nearly 3 feet thick. At 

 Green lake, 3 miles farther east, it is 2 inches thick. On the hill 

 east of Jamesville it is nearly 4 feet thick. Farther east in the vicin- 

 ity of Manlius it is in places a few inches thick and in places absent. 

 Clarke 2 has explained these variations in thickness as more or less 



1 M. C. Ihlseng. Bui. 34, Pa. State College Agr. Exp. Sta., Jan. 1896. 



2 Lenticular Deposits of the Oriskany Sandstone : Science 1900. 



