34 GEOLOGY OF ERIE COUNTY 



Genesee valley lies between the Tully and the Genundewa 

 limestone. At Naples this bed is 95 feet thick but it thins toward 

 the west and eastward it merges with the West river shale in 

 Chenango county. At Mount Morris it is 82 feet thick. 



In Erie county this formation has practically disappeared. 

 At Springbrook it shows in the cliff face as a dark band from 19 

 to 26 inches thick. At Smoke's creek it is absent but is repre- 

 sented by a row of concretions. At the mouth of Pike creek 

 in the lake cliffs it is 12 inches thick. 



At the Springbrook outcrop where it shows to the best 

 advantage the shale is dense, black and slaty. It lies directly 

 upon the layer of pyritiferous shale. Its upper layer is a layer 

 of flat concretions a foot or less in diameter which lie in direct 

 contact with the Genundewa limestone above. 



The Genesee shale is nowhere abundantly fossiliferous. No 

 fossils have been described as having been found in the formation 

 in Erie county. Numerous land plant remains found by the 

 writer at the mouth of Pike creek in loose, black shale were 

 referred by him to the Genesee. 



Genundewa Limestone. 



Lying in the middle of the black and dark gray shales of the 

 Genesee beds is a thin but persistent layer of limestone which, 

 because of the presence in it of innumerable shells of Styliolina 

 fissurella, came to be known as the Styliola band or the 

 Styliolina limestone as named by Dana. This name has been 

 changed to Genundewa limestone due to its exposure at Bare 

 Hill, on the east side of Canandaigua lake, the alleged Genundewa 

 of Seneca tradition. 



The Genundewa limestone, where exposed in the gorge of 

 Eighteen Mile creek, is from four to six inches thick and concre- 

 tionary in character. It is made up of two layers, the Styliola 

 and the Conodont. 



The Conodont bed lies in immediate contact with the Styliola 

 or it is separated by thin layers of dark shale. The Styliola is 

 composed almost entirely of the microscopic shells of Styliolina 

 fissurella. It is argillaceous and gives off the characteristic 

 clayey odor when breathed upon. 



