40 NEW YORK STATE MUSEUM 



4 Camillus shale. Drab, gray, green and red shales with beds 

 of gypsum and dolomite in the upper part. Smaller seams and 

 veins of gypsum are found all through the shale. The total thick- 

 ness reaches 300 feet in the central part of the State. 



3 Syracuse salt. An assemblage of alternating beds of rock salt 

 and shale, not definitely delimited with regard to the Camillus and 

 Vernon shales. The presence of rock salt is the only criterion for 

 its recognition. The salt beds have not been found east of Madison 

 county and they occur only under a thick covering where they 

 have been protected from solution. 



2 Vernon shale. A prominent member of the Salina in the sec- 

 tion west from Herkimer county. Has a thickness of 500 feet in 

 Onondaga county. It is distinguished by a bright red color except 

 in the western part where it is banded with gray and green shales 

 and becomes less conspicuous. 



I Pittsford shale. A local phase of the Salina, notable only for 

 its Eurypterid fauna. The type locality is near Rochester. 



The second area of Salina strata is in southeastern New York 

 and consists of two belts, one of which follows the Shawangunk 

 mountain uplift and the other the parallel Skunnemunk uplift. The 

 principal members are conglomerate, shale and sandstone. No 

 gypsum has been found in this region and in view of the fact that 

 the strata here were accumulated in a separate basin, entirely inde- 

 pendent of the other, its presence may be regarded as very uncertain. 



General features of the deposits. The gypsum as a rule forms 

 regularly stratified beds which are made up of layers varying from 

 a few inches to 4 feet or so thick. The beds are not, of course, 

 continuous throughout the Salina belt, but have the shape of elon- 

 gated lenses which follow each other along the strike and dip with 

 intervals in which they may be absent or of greatly diminished 

 size. The workable deposits are thus segregated into more or less 

 wdl defined areas. When exposed in natural outcrop the bed.s 

 are apt to show irregularities due to solution of the gypsum by 

 ground waters; in this way the entire removal of the gypsum seems 

 to have resulted in some places where it was only thinly covered 

 by shale or limestone. 



The main deposits lie within the upper i^art of the Camillus shales 

 and as the whole formation has a slight southerly dip (about ] 

 foot in 100), their line of outcrop is near the southern border of 

 the Salina belt as traced on the map. A useful indicator in the 

 field is the Bertie waterlime which is more resistant to weathering 

 than the shales and which can often be located by the character 

 of the topography. The gypsum usually occurs within a fe^v feet 

 of the base O'f the waterlime. 



The deposits exhibit a considerable variation of character in dif- 

 ferent parts of the belt. In Madison county, on the eastern end, 

 they consist of a loose friable mixture of gypsum crystals (selenite) 

 and clay, and have originated seemingly by solution and recrystal- 

 lization of former beds or disseminated gypsum. These deposits 



