8 NEW YORK STATE MUSEUM 



of the hydrous sulfate principally in the impure condition and not 

 in.frequentl3^ appears crystallized as selenite and in flaky condition 

 mixed with very soft dark bluish clayey shale. Where the gyp- 

 sum predominates the rock has a distinctly crystalline appear- 

 ance but where the proportion of shale is greatest the lines of 

 sedimentation are very apparent and it has every resemblance to 

 ordinary soft dark shale. Joints occur everywhere throughout 

 the rock beds and through these the percolating waters have had 

 access to the gypsum deposits and have frequently removed them, 

 thereby causing a settling of the shale material adjacent and 

 leaving hemispheric masses between the resultant depressions. 

 Doubtless the present hummocky condition of the beds, not alone 

 in this region but throughout the area of surface exposure of 

 Camillus shales is largely due to causes connected with the change ' 

 from anhydrite to the hydrous sulphate or gypsum. There are a 

 few thin even layers of hard magnesiau limestone interstratified 

 with the gypsum and at the top of the bed there are 8 to 10 feet 

 of soft blocky shales containing but very little gypsum. This lat- 

 ter bed is exposed at the east end of the Lehigh Valley Railroad cut 

 1 mile east of the village of Victor, and also in the bed of Mud 

 creek near the Lehigh Valley Railroad bridge and at Fredon or 

 East Victor. The more productive development of the gypsum in- 

 dustry in this region however is in the territory just east of the 

 quadrangle in the town of Phelps, where for more than 70 years it 

 has been produced on a large scale, though the production has 

 now notably fallen away. 



Bertie waterlime 



This term, derived from Bertie township in western Ontario, is 

 specially characterized by the abundant presence of the crusta- 

 ceans Eurypterus, Pterygotus and Ceratiocaris. It consists 

 chiefly, in the Oanandaigua region, of hard dark impure hydraulic 

 limestone in thick layers separated by thin seams of dark and ap- 

 parently carbonaceous matter. The rock weathers to a light 

 brown or bufi". Thickness 40 feet. 



The passage from the Camillus shales into these beds now termed 

 Bertie waterlime is a very gradual one, the loss of gypsum being 



