ECONOMIC GEOLOGY OF MONROE COUNTY AND CON- 

 TIGUOUS TERRITORY 



BY CLIFTON J. SARLE 



Monroe county, in western New York, has an average length 

 from cast to west of 32 miles, and a greatest breadth of 26. The 

 total area is 6S2 square miles divided into 19 towns. It may be 

 roughly compared to an inclined plane, having an elevation in 

 the southern portion of about 700 feet above tide, and in the 

 northern, at Lake Ontario, of 24G feet, the local base level. 



The broad topographic features of the county are due to the 

 varying character of the underlying rock formations and the 

 consequent difference in the rate of their destruction. Within the 

 area there are one sandstone and four important limestone 

 horizons alternating with five shale horizons. These lie in nearly 

 horizontal layers, their successively truncated edges facing north- 

 ward and stretching eastward and westward through the county. 

 The shales which weather most rapidly, produce areas of de- 

 pression, while the others cause areas of prominence and shelves 

 or platforms. 



Superimposed on these features are those due to the distribu- 

 tion of the drift, often more conspicuous because of their limited 

 extent. The drift, while reproducing in a general way the broad 

 features of the underlying rock surface, is irregular in its dis- 

 tribution. It is usually arranged in more or less well defined 

 east and west ridges, or moraines, though in some parts of the 

 county, it is raised into elongated north and south mounds, or 

 drumlins, both of these forms being the result of direct deposition 

 from the glacier. In addition to these, are other features, the 

 result of the sorting and arranging by water of the material 

 freed from the glacier, such as serpentine north and south ridges 

 of gravel known as eskers, supposed to have been formed beneath 

 the ice sheet by running water; mounds of sand and gravel 

 formed by the debouchure of streams from the ice front into 

 ponded water; beach and bar structures formed in connection 

 with the glacial lake history of the region; gravel lobes formed 

 at the mouths of streams flowing into these glacial lakes from 



