5° 



NEW YORK STATE MUSEUM 



i to 2 feet in thickness, separated by blue or olive shales. Layers 

 of black shale from an inch to 2 or 3 feet thick also occur. 



The proportion of sandstone decreases toward the east and south. 



Fossils are common in several of the heavier layers of sandstones 

 lying 100 to 150 feet above the Grimes sandstones. In a small 

 ravine that crosses the road leading to North Urbana 1 mile east of 

 Hammondsport, there is exposed 40 rods above the crossing a cal- 

 careous lens 1 foot, 6 inches thick and several rods long almost 

 entirely composed of brachiopods and crinoid segments, and several 

 sandstones in the same horizon in the ravine 1 mile south of Ham- 

 mondsport contain the same species. The more common are: 



Goniatites Atrypa spinosa Hall 



Orthoceras sp. Productella lachrymosa Hall 



Leptodesma sp. Ambocoelia umbonata Conrad 



Orthis tioga Hall Spirifer mesacostalis Hall 



Schizophoria impressa Hall . Cyrtina hamiltonensis Hall 



Stropheodonta cayuta Hall Orbiculoidea sp. 



Leptostrophia perplana Conrad var. Crinoids 

 nervosa Hall 



On the Hammondsport and Naples quadrangles the fossils of 

 the West Hill flags and shales are mostly brachiopods, but in the 

 Genesee river section and westward the fauna of the Naples beds 

 prevails and brachiopods are absent. 



The West Hill flags and shales are exposed at the upper end 

 of the ravine \ mile south of Friend ; the Belknap gully and the 

 Wagener gully; and in field and roadside outcrops on the hill north 

 of Hammondsport. The fossiliferous sandstones of this formation 

 produce a series of low cascades in the ravine 1 mile south of Ham- 

 mondsport at 1 1 50 to 1200 A. T., and an exposure of the same hori- 

 zon in the ravine near the corner of the Urbana road 1 mile east of 

 Hammondsport includes the calcareous lens previously mentioned. 

 There are frequent small outcrops of the West Hill flags at North 

 Urbana and along the road to Wayne and the ravine at Bradford 

 is in the softer beds in the middle of this division. There are exten- 

 sive exposures of this formation on West hill at Naples and on East 

 hill at Dansville. It is the upper part of the Gardeau flags in the 

 Genesee river section and includes the strata displayed in the cliffs 

 between the mouth of Wolf creek at St Helena and the high bridge 

 of the Erie Railroad at the top of the Upper Portage falls. 



It appears in the cliffs along the shore of Lake Erie between 

 Dunkirk and Barcelona. It is softer here and includes some heavy 

 beds of black shale. 



