202 NEW YORK STATE MUSEUM 



Upper Helderberg limestones 



The Upper Helderberg formation appears in the Hudson valley 

 at Kingston; thence it runs in a belt west of the river, to the 

 Helderberg mountains, bending to the west-northwest, and thence 

 west it continues across the state to the Niagara river and Lake 

 Erie. The subdivisions are known as the Onondaga, the Cor- 

 niferous and the Seneca limestones. The first is more generally 

 recognized as the ' Onondaga gray limestone ' and the last as the 

 Seneca blue limestone. 



There is much diversity in the limestones of this group in its 

 long range of outcrop. The Onondaga gray stone is gray in 

 color, coarse crystalline; and makes beautiful ashlar work, either 

 as rock face or as fine tooled, decorative pieces. 



The Oorniferous limestone is hard and durable, but it is so full 

 of chert that it can only be used for common wall work. 



The Seneca blue limestone is easily dressed and is a fairly good 

 building stone. 



Limestone of the Upper Helderberg epoch is quarried exten- 

 sively at Kingston, Ulster county, and is a valuable building 

 stone. In Onondaga county there are the well-known Splitrock 

 and Reservation groups of quarries, which have produced an im- 

 mense quantity of excellent and beautiful stone and which has 

 found a market in all of the central part of the state. They are 

 in the lower member of the group. Going west, there are the 

 large quarries in the (Seneca limestone at Union Springs, 

 Waterloo, Seneca Falls and Auburn. The LeBoy, Williamsville, 

 Buffalo and Black Rock quarries are in the Corniferous lime- 

 stone. 



The aggregate output of the quarries in the Upper Helderberg 

 limestones exceeds in value that of any other limestone formation 

 in the state. The many quarries of the Trenton probably pro- 

 duce more stone. 



Tully limestone 

 The Tully limestone lying above the Hamilton shales, is a thin 

 formation which is seen in Onondaga county and to the west — 



