ECONOMIC GEOLOGY 



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pied by these formations, afford transportation facilities and 

 offer inducements to those who are seeking new quarry sites 

 where these limestones may be found in workable extent. 



Niagara limestone 



The Niagara limestone formation is well developed west from 

 Rochester to the Niagara river; and there are large quarries in 

 it at Rochester, at Loekport and at Niagara Falls. The gray, 

 sub-crystalline stone in thick beds is quarried for building pur- 

 poses. It is filled with encrinal and coralline fossils and the un- 

 equal weathering of the matrix and the fossiliferons portions are 

 sometimes such as to give the dressed surface a pitted appearance 

 with cavities which roughen and disfigure it. For foundations 

 and heavy masonry it is well adapted. It has 'been extensively 

 employed in the western part of the state. 



Lower Helderberg limestones 



The Water-lime, Tentaculite and Pentamerus limestones are 

 included in this group. The outcrops are in the Rondout valley, 

 southwest from Kingston to the Delaware river; in the foot- 

 hills east of the Gatskills-4n Ulster and Greene counties; on 

 Becraft's mountain, near Hudson; and in a belt stretching west 

 from the Hudson valley, along the Helderbergs and across Scho- 

 harie into Herkimer county. 



The Tentaculite limestone is dark-colored, compact and in thick 

 beds and can he quarried in large blocks. Some of it can be 

 polished and makes a beautiful black marble, as for example, that 



of Schoharie. 



The Pentamerus limestones, both the lower and the upper, are 

 in thick beds and are gray, sub-crystalline in texture, and look 

 well when dressed. They are adapted to heavy masonry as well 



as for cut work. 



Quarries are opened in this group of limestones in the Scho- 

 harie valley, at Howe's Cave, Cobleskill, Cherry Valley and in 

 Springfield. The quarries west of Oatskill and in Becraft's 

 mountain, near Hudson, are also in it. 



