8o NEW YORK STATE MUSEUM 



Rosendale district and in Schoharie and Onondaga counties. The 

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

 purer layers are employed in Onondaga county for lime-making. 

 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 prominent 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 Manilus 

 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 quite 

 continuously from Buffalo, Erie county, 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 lime- 

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

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

 Rock (near Syracuse), Auburn, Waterloo, Seneca Falls, Leroy, 

 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 

 extent. It finds its principal use in portland cement manufacture, 

 being employed for that purpose by the Cayuga Lake Cement Co. 

 in its works at Portland Point, Tompkins county. 



Marl is a useful substitute for the hard limestones for some pur- 

 poses and is quite extensively developed in the central and western 

 parts of the State. It is found particularly in swampy tracts and 



