60 [Assembly 



sembles the peculiar plumage from which it is named. The 

 abundance of this fossil has given the rock in which it lies the 

 name of " Cocktail grit." 



Upon it lies the Schoharie grit, a thin mass, being usually 

 only four .or five feet of hard calcareous sandstone, which, when 

 freshly quarried, looks like a grey limestone, but when long 

 weathered, loses its carbonate of lime and becomes a gritty 

 yellowish sandstone. It is found only from Cherry-valley east- 

 ward, extending round the front of the Helderbergs and along 

 the hills west of the Hudson, but does not appear to be known 

 in Pennsylvania. Its fossils are numerous and conspicuous : 

 among them may be noticed one or two Trilobites, several Ortho- 

 cerata, and many smaller shells ; of which we cannot furnish 

 illustrations. They are figured in the third volume of the State 

 Palaeontology, and many of them are in the cases in the Cabinet. 



THE UPPER HELDERBERG LIMESTONES 



(which lie above the Schoharie grit, Cocktail grit and Oriskany 

 sandstone, and where these are wanting, as in "Western New- 

 York, lie immediately on the Waterlime group), are some of the 

 most widely known and useful limestones of the State. The 

 lower portion (usually varying from 10 to 20 feet in thickness) 

 is generally a coarse-grained crystalline gray rock, lying in solid 

 layers, and, when free from flint, working well under the hammer 

 and chisel, and often taking a good polish as a marble ; called, 

 from being very extensively quarried in Onondaga county, the 

 Onondaga Limestone. It is easily traced from near Rondout 

 on the Hudson to the Helderbergs, where its outcropping edge 

 turns westward, and runs by Schoharie, Cherry-valley, Bridge- 

 water, Oriskany falls, the falls of the Chittenango below Caze- 

 novia, Onondaga Hill at Split Rock, Auburn, Phelps, Le Roy, and 

 Williams ville to Black Rock. Through nearly all this distance 

 it preserves its well marked character, and is extensively used 

 in building. 



The upper portion of the group is what was originally called 

 the CoRNiFEROus limestone, from its containing beds and nodules 

 of hornstone or flint : it is usually from 30 to 50 feet thick, a 

 bluish or grayish rock, lying in straight courses, often having 

 some shale interstratified with it. Though these two portions of 

 the Upper Helderberg limestone are in most places very distinct, 

 yet in others, especially in the West, they seem to run together or 



