REPORT OF THE STATE PALEONTOLOGIST 1902 



1003 



tions from 1 inch to 1 foot in diameter are common throughout 

 the mass, and appear in the rock wall at some horizons in well 

 denned rows. 



Fossils are not abundant in any part of these shales, 

 but a few specimens occur in the lower part; they are much 

 more common in the upper part, where they are found in con- 

 siderable numbers in a few thin layers of shale and also in the 

 concretionary layers and the separate concretions. 



A row of concretions, usually a foot or more in diameter at 

 the top of these shales and exposed in the riyer section, rests 

 on a calcareous layer V2 mcn to 2 inches 

 thick that is composed of fossils, many of 

 which are finely preseryed. This row of 

 concretions is found at this horizon in 

 nearly all the exposures of the shales 

 from the Bristol valley, Ontario county 

 on the east, to the Tonawanda valley, 

 Wyoming county on the west. 



It is exposed in the cliffs along th< j 

 Genesee riyer for about 3 miles and conies 

 down to the water level at the north end 

 of Smoky hollow. 



The passage from the Cashaqua shales 

 to the next succeeding formation is 

 through alternations of light and dark 

 shales, like those below, and the line of 

 separation is therefore an arbitrary one. 



In the thickness given, 165 feet, nearly 

 all of the transition layers at the top and 

 bottom are included. Like the Hamilton. 

 Grenesee and the Middlesex shales, the 

 Cashaqua shales thin toward the west, 

 their thickness in the Lake Erie section 

 being only 32 feet. In the Naples section 

 farther east (Ontario county) there are 

 237 feet of shales and thin sandstones in this subdivision of the 

 Portage formation. 



Alternate layers of black and gray shale overlie the fossilifer- 

 ous concretions at the top of the Cashaqua beds to the thickness 



sandstone 



light shale 



black shale 

 light shale 



Fig. 3 Section at Lower 

 Portage falls. Station 9 



