Bishop — Geology ok Erie County. 



315 



boundary between the two formations must therefore lie betw een here and the 

 Lehigh docks, and it is very probable that Stony Point itself marks the 

 extension of the Stafford limestone into the lake. It may be assumed, 

 therefore, that the boundary between the Corniferous limestone and 

 Marcellus shales, as laid down on the accompanying map, is a very close 

 approximation to the actual one 



HAMILTON GROUP. 



Marcellus Shales and Limestone. 



The best section within the county of the lower Marcellus beds occurs 

 in the vicinity of Lancaster. In Cayuga creek, just above the lower bridge, 

 is a layer about two feet thick, of a firm, jet black shale containing some iron 

 pyrites in crystals and concretions. This is overlaid by a foot or more of 

 grey limestone which had been mostly quarried out and could not be 

 accurately measured. From the bridge up to near the Lake Como dam, the 

 rock does not show. Just below the dam, the black shale crops out, 

 capped by the Stafford limestone, which was at one time quarried here. A 

 careful estimate, based upon the thickness of the rock in sight, the fall of the 

 stream, and the measured height of a dam in the village, shows that the rock 

 from the lowest visible stratum is from fifteen to twenty feet below the 

 Stafford limestone. On a little brook running through the centre of the 

 village, there is a tine exposure of the Stafford limestone. In sight, at the 

 base of this, is a two-foot layer of jet black bituminous shale, smelling 

 strongly of petroleum and containing pyritous concretions. Above this are 

 the limestones in layers of the following thickness: 



Lowest — 12 inches, containing Orihoceras. 



6 

 14 



10 " 

 18 " 



14 " with a little flint at the top. 

 14 



12 " 

 Total, 9 ft. 4 in. 



Above Lancaster, the shales are black, thin-bedded, friable and show 

 very regular jointing. Farther up, the layers become more calcareous, 



