GEOLOGIC FORMATIONS OF NEW YOKE 159 



Oriskany sandstone 



This rock which overlies the Lower Helderberg group, is, at 

 Oriskany Falls, whence it derives its name, a coarse light colored 

 sandstone about 20 feet thick. In localities further west it is 

 sometimes, as at the falls of the Chittenango creek and at Split 

 Rock near Syracuse, either wanting or represented only by a few 

 inches of dark sandy rock; sometimes, as between Elbridge and 

 Skaneateles, 30 feet thick; and in other localities, of various 

 intermediate thicknesses. Near Schoharie, it contains some lime 

 with its sand, and is light colored; in some parts of the Helder- 

 berg region, as near Clarksville, and Knox, it is only a foot or two 

 thick, a hard, dark colored stratum full of fossils and having" 

 on its upper surface myriads of impressions of the Spirophyton 

 cauda galli. In Pennsylvania, it is from 150 feet to 300 feet in 

 thickness, and contains the same organic remains which are 

 found in it in New York. 



Cauda Galli Grit 

 Above the Oriskany sandstone, in the Helderberg region, is 

 a mass of sandy slate or shale, often more than fifty feet thick; 

 but it is not known west of Herkimer county. In Pennsylvania, 

 it is seen from the state line to the Water Gap. It is valuable 

 as a road metal though not very durable and forms, by decom- 

 posing, a poor soil. It is equally barren in fossils, the only form 

 known being what is called the Cocktail fucoid, Spirophyton 

 cauda galli, supposed to be the remains of a marine plant, the 

 form of which resembles the peculiar plumage from which it is 

 named. The abundance of this fossil has given the rock in which 

 it lies the name of c Cauda galli grit. b 



Schoharie Grit 

 Upon it lies the Schoharie grit, a thin mass, usually only four 

 or five feet of hard calcareous sandstone, which, when freshly 

 quarried, looks like a gray limestone, but when long weathered, 



a This important fact is not noted by either Mather or Lincklaen though it must 

 have been observed by them. F. J. H. M. 



6 A.s I have noted under Oriskany, this fossil is not confined to the Cauda galli and occurs on 

 the Oriskany sandstone. F J. H. M. 



