GEOLOGICAL SURVEY OF THE STATE OF NEW YORK. 



(GEOLOGICAL MAP.) 



Report on the Structural and Economic Geology 

 of Seneca County. 



By D. F. LINCOLN, M. D. 



Contents 



Introductory. Surface Geology. — Topography of plateau, hills, ravines^ 

 alluvial belt, drumlin belt, sand ridges, kame district, delta terraces, drift- 

 filled channels, till, glacial striation, springs, Seneca lake. Stratigraphic 

 Geology. — Salina group. Lower Helderberg group. Oriskany sandstone. 

 Marcellus shales. Hamilton shales. Tally limestone. Genesee shales. 

 Portage group. Thickness and dip. Economic Geology. — Clay, brick, tile, 

 limestone, sandstone, plaster rock, road metal, gas ivells, water power. 



The county of Seneca, selected for the present report, is fairly- 

 representative of central l^ew York in point of geological devel- 

 opment and in respect to its economic resources. 



Geologically, it presents the upper number of the Silurian 

 formations, with the lower, middle and part of the upper Devo- 

 nian. The formations exposed are the following : 



Devonian, upper: Portage sandstone and shale; Genesee 

 shale. 



'- Devonian, middle: Tully limestone; Hamilton shale and 

 limestone ; Marcellus shale. 



Devonian, lower : Upper Helderberg limestone. 



Silurian : Water lime ; Salina. 



Map of the County. 



The map here given is reproduced from a wall map of Seneca 

 and Cayuga counties, published in 1859 by A. E. Z. Dawson, 

 Philadelphia. 



In the copy, roads are denoted by single lines. Except in the 

 northern part of the county, they are introduced sparingly, for 

 the purpose of marking geological points. Hamlets are marked 



