REPORT OP THE DIRECTOR AND STATE GEOLOGIST 1903 107 



There is scarcely any well defined division between tlie shales 

 and shaly limestones of the third division and the so called mag- 

 nesian deposit which overlies it.^ 



An investigation of the rocks near the plaster quarries at Union 

 Springs has led Mr S. G. Williams to refer the gypsum deposits 

 at this point to the Lower Helderberg; and his grounds for this 

 supposition are here quoted in his own words. ^ 



It is well known to geologists that the strata containing the 

 gypsum deposits of New York, ranging from Madison county west- 

 ward, at the time of the State Geological Survey were all assigned 

 to the third of the four groups into which the Salina period was 

 divided ; and that these gypsum deposits were described as isolated 

 masses of possibly concretionary character contained in the in- 

 closing beds. The gypsum beds a short distance north of Union 

 Springs, Cayuga co. are much the most extensive of these deposits. 

 A recent examination of the g3''psum beds and their inclosing 

 strata, accompanied by some fortunate discoveries of somewhat 

 abundant though often badly preserved fossils, has not only shown 

 that the gypsum in this locality exists in continuous beds with a 

 considerable degree of regularity, but has also afforded reasons for 

 believing that this portion of the gypseous series belongs rather 

 with the Lower Helderberg than with the Salina. 



A section at this point eastward, and thus nearly in the line of 

 strike, from the level of Ca;y'uga lake to the top of the Oriskany 

 sandstone, is about 114 feet thick and consists of the following 

 members, numibered upward from the lake level. 

 No. 8 Oriskany sandstone in a single fossilferous 



seam 3 feet 8 inches 



7 Drab limestone, upper beds with thin, un- 

 dulating laminae : exposed 10 " 

 6 Limestone revealed only in occasional out- 

 crops, leveled with Locke level, about 46 '^ 

 5 Thick bedded blue limestone, containing 

 MeristelJa laevis, Orthis ohlata, small 

 form, RyncJionella semiplicataj Strop- 

 hondonta varistriata, etc. 10 " 

 4 Drab limestone, holding a branching fucoid 



and Niicleospira ventricosa 4 " 



3 Measures concealed, leveled with Locke 



level 20 " 



2 Thin bedded blue limestone, terminating 



below with a seam 2 feet thick 4 " 



1 Drab limestone unevenly bedded with two 



or three thin blue seams, to lake level 16 " 



^N. Y. state Mus. Bui. 11. 3:24-25. 

 'Am. Jour. Sci. Sep. 1885. 



