GYPSUM DEPOSITS OF NEW YORK 



25 



opinion that they are attributable to tl:e removal by underground 

 waters of the shale along the contact which has caused it to subside 

 and to fill in the hollows between the gyps-um masses. He does not 

 give, however, any explicit reasons for the peculiar shapes assumed 

 by the gypsum and one might even conclude that he considered 

 such masses to occur very generally throughout the Salina belt. 



The significance of these irregular discontinuous deposits has been 

 misinterpreted in some descriptions, owing to which the sedimentary 

 origin of the gypsum seems to have been seriously questioned by 

 geologists. There can be no reason to doubt that they are of super- 

 ficial distribution and represent the remnants of former lenses of 

 normal type partly dissolved aw^ay by ground waters. If followed 

 along the dip of the strata, they w^ould be found probably to lose 

 their irregular form and merge into the usual bedded deposits. The 

 solvent efifect of ground waters upon the gypsum is shown in numer- 

 ous places on the outcrop ; the joint and bedding surfaces are often 

 deeply pitted, and secondary veins of gypsum may be observed ex- 

 tending into the shales. 



Fig. 3 Irregular bodies of gypsum resulting from solution of a once continuous bed. 



(After Hall) 



Fig. 4 Bed of gypsum partly dissolved away. (After Hall) 



