Report of the State Geologist. 17 



The Structural and Economic Geology of Erie County. 

 By [. P. Bishop. 



After a brief introductory account of the topography of this region is a 

 more detailed description of the stratigraphic succession of the rocks. The 

 lowest rocks are the shales and marls of the Salina group, and the highest, 

 according to this author's determination, the upper beds of the Portage group. 



Each subdivision is described at considerable length, and features of 

 special interest are the accounts given of the extensive water-lime beds, the 

 limestones of the Upper Helderberg division, the Stafford limestone of the 

 Marcel lus shale, the Encrinal limestone of the Hamilton group, and the 

 section of the Genesee slate. It is shown that the Tully limestone, which is 

 absent in all the country west of Canandaigua lake, is here represented by a 

 layer of pyrite at the top of the Hamilton shales, as shown by T). D. Luther to 

 be the case in the counties eastward between Erie and Ontario. The section of 

 the Genesee slate has a thickness of only seventeen feet, about two feet of 

 this belonging to the Styliola band, which has thus been shown to extend from 

 Yates county to Lake Erie. The lithologic characters of the Portage shales 

 and sands are carefully given, but their fossils have received little attention 

 in this connexion ; the upper limit of this formation, in the region 

 described, is not clearly determined. 



Superficial deposits, sands, gravels and clays are treated under the head 

 of " Quaternary geology, 1 ' and in connexion therewith is an account of the 

 soils, springs, pre-glacial rivers and erosion, and the ancient Lake Erie shore 

 line in Buffalo. This part of the paper closes with a brief notice of modern 

 geologic changes. 



The second main heading is that of economic geology, under which are 

 considered, first, the rock formations quarried for building stone, viz.; the 

 hydraulic limestone, Onondaga limestone, Corniferous limestone, Stafford 

 limestone, Encrinal limestone and Portage sandstones. The interests here 

 represented are large, as shown by the statistics of producers, and the quality 

 and amount of the products. Similar consideration is given to the product of 

 road metal. 



Following this is an extended description of the production and manu 

 facture of hydraulic cement; the nature of the cement rock and a list of its 

 fossil contents. The production of quicklime, brick, tile, sewer pipe and fire 

 clays, sand and gravel, is also described at length. 



