GYPSUM DEPOSITS OF NEW YORK 21 



divides them into separate beds, though there is Httle regularity in 

 the number or thickness of the beds from place to place. The shale 

 intercalations range all the way from mere films to layers several 

 feet thick. While the main body of gypsum is usually found near 

 the top of the Camillus shale, in some places directly beneath the 

 waterlime, there are noduies, veins and layers of gypsum distrib- 

 uted all through the mass. 



The limestone layers accompanying the shale represent transition 

 stages toward the Bertie waterlime and are more abundant in the 

 upper part. They show the saiiie porous structure and hopper- 

 shaped casts due to halite and contain varying percentages of 

 magnesia. They are inclined to be more argillaceous than the char- 

 acteristic waterlime, as might be expected, and on that account dis- 

 integrate rapidly when exposed to the weather. 



The whole body of shale is impregnated more or less with lime 

 and is often called marl in the reports of James Hall. The lime, 

 however, is not of organic origin, but a precipitate probably from 

 infiltering waters subsequent to the consolidation of the beds. 



Syracuse salt. This is a very variable member composed of alter- 

 nating beds of rock salt and shale, occupying a position between the 

 Camillus and \'ernon shales. There is no definite plane of demar- 

 cation at the top or bottom, and some geologists consider it a pai't 

 of the Vernon shale rather than an independeijt unit, inasmuch! 

 as the presence of rock salt constitutes the only criterion for its 

 recognition. Even that feature does not hold along the outcrop, for 

 the salt has been removed in solution wherever the covering is less 

 than about looo feet thick. 



From the records of deep wells, the salt horizon is recognizable 

 in the Salina from IMadison county westward to Erie county. At 

 Morrisville, Madison co. a single bed of salt about 12 feet thick 

 occurs.^ In Onondaga county there are as many as four beds of 

 salt separated by shale and the extreme thickness of the salt and 

 included rock is not less than 300 feet. At Ithaca seven beds of 

 salt aggregating 248 feet and six beds of included shale with a total 

 thickness of 222 feet are shown in a well record. In the Genesee 

 valley, at the Retsof mine, the salt beds include 15 feet of rock and 

 measure altogether 124 feet. In the Oatka valley of Genesee county 

 the salt-bearing strata are from 100 to 135 feet thick. In Erie 

 county they appear to range between 100 and 200 feet thick. 



• The data relating to the thickness of the salt deposits are taken froni 

 Luther's " Geology of the Salt District." N. Y. State Mus. An. Rep't 50, 

 V. 2. 1896. 



