826 NEW YOKE STATE MUSEUM 



The physical and chemical characters of the shales can be judged 

 from some of the tests given beyond under the locality descrip- 

 tions. 



The shale^bearing formations occurring in ISTew York state, be- 

 ginning with that geologically oldest, are as follows : 



Lower Silnrian Hudson river 



■"■"I f Medina 



TT 0-1 • ■ ! Clinton 



Upper bimrian 4 ^^. 



JNiagara 

 "] I Salina 



f Hamilton 



Devonian -{ Portage 



1^ Chemung 



A geological map will show the outline of the area underlain 

 by the outcropping edges of each shale formation, and it will be 

 noticed that they form bands of variable width extending across 

 the state from east toi west. ' 



As the formations have a slight dip (40-60 feet a mile) to the 

 south, the belts of shale encountered in crossing the state from 

 south to north will be successively older. 



Turthermore any one bed will of couse be higher above sea 

 level to the north than to the south. The Chemung shales underlie 

 the whole surface in the southern part of the state, but as we 

 proceed northward they are found only on the ridges of the higher 

 hills, the sides and bottom of the valleys being underlain by the 

 Portage shale, which in turn succeeds the Chemung as the surface 

 formation. 



Distribution and properties 



Hudson river. This formation is abundantly displayed m the 

 counties of Lewis, Oneida, Montgomery, Schenectady and Colum- 

 bia. Its tendency is to exhibit silicious or slaty phases, but in 

 eastern Ct)lumbia co. it becomes at times argillaceous and at the 

 same time contains considerable iron. 



Medina. The Medina formation at times ia shale-bearing, as 

 along the Genesee river, where it is also marly, but the extent of 



