262 NEW YORK STATE MUSEUM 



^6 Beekmantown limestone, Ogdensburg. Howard's qiiarn-, upper part. 

 N. Y. State Museum Bui. 44. 



7 Beekmantown limestone, Ogdensburg. ard's quarrj', lower part. 

 Idem. 



8 Chazy limestone, Chazy. D. H. Newland, analyst. Idem. 



9 Chazy limestone, Willsboro Point, Essex county. T. G. White, analyst. 

 Idem. 



10 Trenton group. Smith's Basin, Washington county. Keenan quarry. 

 Idem. 



11 Trenton group. Smith's Basin, Keenan quarry. H. Ries, analyst. Idem. 



12 Trenton group, Whitehall. Harris quarry. Idem. 



13 Trenton group, Glens Falls; upper bed. Idem. 



14 Trenton group. Glens Falls; lower bed. Idem. 



15 Trenton group, Amsterdam. Hewitt quarry. Idem. 



16 Trenton group, Amsterdam. Hewitt quarry; upper layer. Idem. 



17 Trenton group, Ingham Mills, Herkimer county. Butler quarry. Idem. 



18 Trenton group, Ingham Mills, Herkimer county. Butler quarry. Idem. 



19 Trenton group. Prospect, Oneida county. J. D. Ir</ing, analyst. Idem. 



20 Trenton group, Low\'ille. J. Watson's'quarr^^ Idem. 



21 Trenton group, CoUinsville. Lewis county. Roberts quarry. D. H. 

 Newland, analyst. Idem. 



22 Trenton group. Port Leyden. Snyder quarry. D. H. Newland, analyst. 

 Idem. 



Silurian limestones. The lowermost formations of the Silurian 

 comprise slates and sandstones without any calcareous beds. In 

 the middle or Niagaran group these rocks become important and 

 are divided among the Clinton, Lockport and Guelph members. 



The Clinton limestone appears mainly in the western section of 

 the Clinton belt of strata which outcrops all the way from Otsego 

 county to the Niagara river, on a line a little south of the Mohawk 

 river, across Oneida lake and thence directly west. East of Rochester 

 the limestone occurs in thin, discontinuous, usually shaly layers, 

 intercalated in shales which constitute the main element. To the 

 west of that locality it thickens and in Niagara county greatly 

 predominates over the shale, having a thickness altogether of about 

 30 feet. The upper 10 or 12 feet of the succession consist of light- 

 colored fossiliferous beds which are fairly pure calcium limestones. 

 The middle and lower parts are more silicious and the middle layer 

 is a dolomite. On account of the scarcity of high calcium limestones 

 in the Vv^estern part of the State, for which a large demand exists in 

 Buffalo and vicinity, the Clinton beds have considerable economic 

 importance, and large quarries have been opened near Pekin and 

 Gasport, Niagara coimty. The principle use of the product is for 

 flux in iron blast furnaces. 



The Lockport and Guelph are magnesian limestones or dolomites. 

 They are quite similar in general characters but differ in their fossil 

 content. The Lockport is the more persistent formation and outcrops 

 m a belt, some 4 or 5 miles wide, from Niagara Falls to the western 

 border of Onondaga count}^ whence it can be traced with diminishing 



