28 NEW YORK STATE MUSEUM 



shale near the base, much heavier on the shore of Lake Erie, has 

 been designated the " Dunkirk black shale." The aggregate thick- 

 ness of the Gardeau beds on these quadrangles is approximately 

 300 feet. 



Fossils are very rare in most of the strata, except some of the 

 light colored soft shales, where they are fairly common. The 

 fauna is composed of the following species : 



Manticoceras rhynchostoma Clarke 

 M. pattersoni Hall 

 M. oxy Clarke 



Tornoceras uniangulare Conrad 

 Orthoceras pacator Hall 

 Bactrites aciculum Hall 

 Styliolina fissurella Hall 

 Phragmostoma natator Hall 

 Loxonema multiplicatum Clarke 

 Palaeotrochus praecursor Clarke 

 Lunulicardium bickense Holzapfel 

 Honeoyea erinacea Clarke 

 H. major Clarke 

 H. desmata Clarke 

 Posidonia attica Williams 

 Ontaria suborbicularis Hall 

 O. clarkei (Beushausen) 

 Euthydesma subtextile Hall 

 Buchiola retrostriata von Bitch 

 B. lupina Clarke 

 Paracardium doris Hall 

 Pterochaenia fragilis Hall 

 Hydnoceras nodosum Hall 

 Cladochonus sp. 

 Lignites. 



Exposures. Exposures of the Gardeau flags and shales are in 

 all the ravines on the west side of the Tonawanda Creek valley, 

 and specially good ones are in the large ravine above the railroad 

 west of Varysburg, and in the large Stony Brook ravine east of 

 that village. The flags and heavier sandstones crop out in many of 

 the small gullies in the towns of Bennington and Sheldon and those 

 in the southern part of Attica. 



NUNDA SANDSTONES 



Toward the west from the Genesee River gorge at Portageville 

 where this formation is a nearly homogeneous mass of compact 

 light bluish gray sandstone nearly 200 feet thick, it gradually be- 

 comes softer and more shaly. This tendency appears to be stronger 

 in the lower portion, reducing the thickness of the strata retaining 



