THE MINING AND QUARRY INDUSTRY I915 63 



worked to some extent in Wayne, Onondaga and Madison counties. 

 The Guelph, also a dolomite, occupies a limited area in Monroe 

 and Orleans counties and is worked near Rochester. 



The Cayugan group includes among its members the Cobleskill, 

 Rondout and Manlius limestones, which are economically impor- 

 tant. They have furnished large quantities of material for the 

 manufacture of natural cement, being the source of the cement 

 rock in the Rosendale district and in Schoharie and Onondaga 

 counties. The cement rock of Erie county is found in the Salina 

 formation. The Manlius limestone is used for portland cement in 

 the eastern part of the State. 



At the base of the Devonic system appears the Helderbergian 

 group which is very important for its calcareous strata. Lime- 

 stones of this age are strongly developed along the Hudson river 

 in Albany, Columbia, Greene and Ulster counties. The Coeymans 

 or lower Pentamerus and the Becraft .or upper Pentamerus lime- 

 stones afford material for building, road metal, lime and portland 

 cement. The limestone for the portland cement works at Hudson 

 and Greenport is obtained from Becraft mountain, an isolated area 

 of limestones belonging to the Manlius, Helderbergian and Onon- 

 daga formations. The works at Howes Cave use both the Manlius 

 and Coeymans limestones. Extensive quarries are located also at 

 Catskill, Rondout and South Bethlehem. 



The Onondaga limestone, separated from the preceding by the 

 Oriskany sandstone, has a very wide distribution, outcropping 

 almost continuously from Buffalo eastward to Oneida county and 

 then southeasterly into Albany county, where the belt curves to 

 the south and continues through Greene, Ulster and Orange counties 

 to the Delaware river. It is in most places a bluish gray, massive 

 limestone with layers and disseminated nodules of chert. The 

 chert is usually more abundant in the upper beds. The limestone 

 finds use as building stone and the less silicious materials also, 

 for lime-making. Quarries have been opened at Kingston, Split 

 Rock (near Syracuse), Auburn, Waterloo, Seneca Falls, Le Roy, 

 Buffalo and other places. 



The Tully is the uppermost of the important limestone forma- 

 tions and likewise the most southerly one represented in the central 

 part of the State. Its line of outcrop extends from Ontario to 

 Madison county, intersecting most of the Finger lakes. Its thick- 

 ness is not over 10 feet, and on that account can not be worked 

 to advantage except under most favorable conditions of exposure. 

 For building stone it is quarried only locally and to a very limited 



