GEOLOGY OF THE ATTICA AND DEPEW QUADRANGLES 2J 



Canandaigua Lake valley. In Ontario and Livingston counties they 

 are succeeded by a band of compact sandstone designated the Grimes 

 sandstone. 



The beds become softer toward the west and lighter colored, 

 though black bands are frequent. Large flat concretions are com- 

 mon in the lower part and there are a few flags. Iron pyrite in 

 nodules and small nodular masses is quite common in both shales 

 and sandstones at some localities. Fossils are somewhat rare in 

 this member of the series, but occur quite frequently in the lower 

 beds and become more common toward the west. 



The larger concretions mentioned contain very fine goniatites and 

 other species along the Lake Erie shore. The fauna includes : 



Manticoceras rhynchostoma Clarke 



M. oxy Clarke 



M. sororium Clarke 



M. pattersoni Hall 



Tornoceras uniangulare (Conrad) 



Bactrites aciculum Hall 



Ontaria suborbicularis Hall 



Buchiola retrostriata (von Buck) 



Paracardium doris Hall 



Pterochaenia fragilis (Hall) 



Cladochonus sp. 



Lignites and fucoids also occur. 



Exposures. Along Crow creek above the reservoir 2]/ 2 miles 

 southeast of Attica ; in Tannery brook below Danley Corners ; in 

 the ravine of the Right branch of Cayuga creek below Bennington, 

 and along Hunters creek a mile southwest of Wales Center, and 

 along the road leading west from Jewettville. 



GARDEAU FLAGS AND SHALES 



As set forth in New York State Museum Bulletin 118, this term 

 is now used to designate the strata resting upon the Grimes sand- 

 stone in Livingston and Ontario counties and succeeded by the 

 Nunda sandstones. The Grimes sandstones thin out westwardly 

 and have not been traced to these quadrangles with certainty, but 

 an arenaceous band consisting of two or three sandstones 12 to 

 18 inches thick that appears to be at or near the Grimes horizon 

 marks a change in the sedimentation and is here considered the 

 base of the Gardeau beds. 



This formation is composed of sandstones, thin flags, hard sandy 

 shales, soft clayey shales and in the lower part a considerable pro- 

 portion of dark to black shale that increases toward the west and 

 large calcareous concretions occur in all parts. A bed of black 



