234 



Repokt of the State Geologist 



Iu this region the upper part of these beds consists of black, fissile, much 

 jointed and highly bituminous shales (the Gardeau shales of Professor Hall) 

 of which about forty feet are exposed in the section near the railroad bridge. 

 Owing to the dip of the strata, and the direction of the upper part of the 

 stream, these rocks form the walls of the gorge for many miles above the 

 bridge. Overlying these are olive shales and arenaceous beds. 



Below the black shales occur about thirty feet of greenish-grey shales, 

 readily weathering into clay, and embracing many layers of concretions 

 These are^the Cashaqua shales of the New York reports. 



Genesee slate. 



These beds have a total thickness of about nineteen feet. The upper 

 nine and one-half feet are black, fissile shales, resembling some of the Gardeau 

 shales, but they are usually more stained by iron oxide, owing to the decom- 

 position of pyrite, which is present in great abundance. Below the black are 

 the grey Genesee shales. These are eight and one-half feet thick, of a greenish 

 grey color and include, near the base, several thin beds of black shale, as well 

 as several thin limestone layers. Below these, and frequently forming the base 

 of the Genesee formation in this region, is a limestone bed six inches in thick- 

 ness, representing the Stylwla layer of Clarke, which is literally com 

 posed of the shells of Styliolina jtssurella (Styliolina limestone, Dana's 

 Manual, 4th ed.) Immediately beneath this bed, in some of the sections, and 

 often united with it into a single bed, is the Conodont layer of Hinde,* 

 which, as will be shown later, belongs to the Genesee rather than to the 

 Hamilton stage. Occasionally a few inches of barren shale, sometimes with 

 spores, underlie the Conodont bed, and form the base of the Genesee slate. 



Hamilton Group — Hamilton stage. 



The Moscow or Upper shales have a total thickness of seventeen feet 

 of which the upper twelve or fourteen inches represent transitional layers 

 to the rocks above. The shales are grey or purplish-grey in color, some- 

 what calcareous, and poorly laminated. They embrace several courses 

 of concretions, and are not very rich in organic remains. The presence 

 of plant remains, and the general condition of the beds, indicate rather 

 shallow water. This is furthermore indicated by a well-worn quartz pebble 

 and a worn fragment of a Spl rlfer granulosus both of which were found in 



•Q. J. Hinde, On Conodonts, etc. Quart. Journ. Geolog. Soc, Vol. XXXV, p. 352, 1880. 



