GEOLOGY OF THE GENEVA-OVID QUADRANGLES 



9 



At Buffalo there have been collected from the Bertie limestone, 

 the ostracod Leperditia scalar is Jones, Ceratio- 

 c a r i s accu m i n a t a Hall and an extensive eurypterid fauna. 

 A few lingulas, Orbiculoidea and other brachiopods occur in the 

 lower layers at Union Springs. 



Cobleskill waterlime 



In this locality this formation is composed of three or four layers 

 of hard, dark limestone that after long exposure weathers to a dark 

 brown. 



It is exposed on the Geneva quadrangle only in the old McQuan 

 quarry a mile southwest of Seneca Falls, where the upper layer, a 

 compact coralline stratum 7 feet thick, and 1 foot of similar rock 

 below without coral, yet remains uncovered. 



The lower part not being exposed the actual thickness of the 

 formation here is not known but on Frontenac island at Union 

 Springs it is 8 feet, 6 inches thick and as it increases slowly toward 

 the west 10 to 12 feet is a fair estimate of its thickness in this 

 quarry. 



In the western part of the State where the Cobleskill is known 

 to quarrymen as " bullhead " it is lighter colored, scraggy and con- 

 tains many small cavaties produced by the weathering out of small 

 fossils and crystals of calcite. 



It is everywhere quite fossiliferous. The heavy layer in the 

 McQuan quarry is largely composed of the coral, Stromato- 

 pora concentrica Hall and on Frontenac island where the 

 exposure is specially favorable for collecting and where fossils are 

 more than commonly abundant, 30 species have been found to occur. 

 Of these, the more common forms next to the Stromatopora are : 



Favosites niagarensis? Hall 

 Halysites catenulatus Linne 

 Cyathophyllum hydraulicnm Simp- 

 son 



Spirifer crispus var. corallinensis 

 Grabau 



Stropheodonta varistriata Conrad 

 Whitfieldella sulcata (Vanuxem) 

 Ilionia sinuata Hall 

 Trochoceras gebhardi Hall 

 Leperditia alta (Conrad) 



Rondout waterlime 



Overlying the Stromatopora layer in the McQuan quarry there 

 is a bed of dark somewhat shaly magnesian limestone 9 feet thick, 

 some parts of which are dolomitic. It is the only exposure on this 

 quadrangle of the Rondout waterlime, a formation 40 feet thick in 



