8 GKOLOGY OF ERIE COUNTY 



(1) Black shale in the river bed. 



(2) Greenish shales containing nodules of gypsum, one and 

 one-half feet. 



(3) Iyight colored, soft, friable, gypseous shales, five feet. 

 The Camillus shale is of great economic importance owing 



to its included deposits of gypsum. This is mined and calcined, 

 and marketed under the name of plaster or plaster of Paris. It 

 is the basis of the ' ' hard wall plaster ' ' in common use in the 

 building trades, and combined with wood fibre it forms "wall 

 boards ' ' which have nearly supplanted lath and plaster in the 

 construction of wooden houses. It is essential in mold making 

 in potteries and in the manufacture of casts. It enters into the 

 manufacture of cement. 



In Erie county the mining of gypsum has been carried on 

 extensively in the vicinity of Akron. In 1913, however, only one 

 plant was at work and this was shipping the crude mineral to 

 other places to be calcined. 



Bertie Limestone. 



The upper Camillus shales become more and more calcareous 

 and magnesian in content toward the top and finally by gradual 

 stages take on the nature of dolomitic limestone. This has 

 received the name of Bertie limestone from the outcrops at 

 Bertie, in Ontario. It extends eastward to Otsego county. A 

 well core in the Museum of the Buffalo Society of Natural 

 Sciences shows this limestone to be 55 feet thick where the 

 formation crosses Main Street, Buffalo. The upper layers 

 constitute a natural cement rock which has been burned for 

 hydraulic cement. This cement rock lies in beds a foot thick or 

 less, separated by thin, dark layers. The limestone is dark gray 

 when first exposed but becomes lighter when exposed to the 

 weather. Freshly exposed blocks tend to break with a decided 

 conchoidal fracture when struck with a hammer. 



The upper beds of this rock are exposed in the Barber 

 Asphalt Company's quarry on Fillmore Avenue, Buffalo, where 

 they may be seen to advantage. They are exposed in nearly all 

 the deeper quarries along the " L,edge " from Buffalo to Akron. 

 At Falkirk, 16 feet of the upper beds are exposed to advantage 

 in the falls of Murder creek, and lower beds are to be seen in the 

 creek bed between the falls and the railway bridge. 



