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NEW YORK STATE MUSEUM 



fissile on exposure and splitting into large flat plates. Owing to 

 their rigidity these shales are traversed by parallel series of 

 joints intersecting each other at different angles and producing 

 in cliff exposures striking masonry effects like buttresses and 

 bastions and on the surface of horizontal exposure equally strik- 

 ing tesselations, triangles, rhomboids, diamonds and kindred 

 forms. Intermingled with these beds are well defined hori- 

 zontal rows of calcareous concretions. Occasionally a thin 

 plate of limestone is shown. The beds also contain iron pyrites in 

 nodules and nodular layers. This mass at once recognized by 

 its structural characters as indicated has a thickness of 95 feet 

 and is terminated by the Styliola limestone or as here designated, 

 the Genundewa limestone. All these shales are extremely sparse 

 in fossils, more highly bituminous beds showing remains of plants 

 and Conodont teeth, and where the beds become a little bluer and 

 slightly calcareous are Lingulas and Orbiculoideas with Ptero- 

 chaenia fragilis. 



These strata are finely exposed all through the upper parts of 

 the ravines on the east side of the lake from Gooding landing 

 southward to Fishers and in the shore cliffs to Genundewa which 

 lies at the base of Bare hill as it is termed on the map; on the 

 opposite side of the lake in the shore cliffs from Hicks point north- 

 ward to Black point, and in the lower part of the ravine at Seneca 

 point and the upper parts of ravines back of Grange landing, 

 Victoria glen and Foster point, and throughout most of the roc k 

 section in the Menteth ravine back of the village of Cheshire. In 

 the Bristol valley the upper parts of all the ravines heretofore 

 mentioned from South Bloomfield to Vincent and also at Baptist 

 hill show these rocks. They appear as far north as the upper 

 reaches of Shaffer creek near the western town line of Canan 

 daigua, and west to Baptist hill along the valley of Beebe brook. 



Genundewa limestone 



A dark gray limestone in layers of from 2 to 10 inches in thick- 

 ness separated by dark or black shale. Some of the layers are 

 even and flaggy, others arc concretionary and nodular. Where 

 purest the limestone is almost wholly composed of the shells of 



