l8 NEW YORK STATE MUSEUM 



south branch of Smoke's creek a mile below Windom, and a 2 

 foot band of calcareous shale in the cliff at Bay View. 



Outside of this quadrangle the Skaneateles shale is exposed in 

 the bed of Mud creek below Wheeler in Ontario county ; in Great 

 gully, 3 miles south of Union Springs, Cayuga county, and in the 

 Bear mountain ravine near Tully valley in Onondaga county. 



Fossils are rare except in the lower calcareous shale. The fol- 

 lowing is a list of fossils reported as obtained from these shales by 

 A. W. Grabau: 

 Phacops rana {Green) Chonetes mucronatus Hall 



yphaeus boothi {Green) C. setigerus Hall 



Primitiopsis punctilifera {Hall) C. scitulus Hall 



Orthoceras sp. C. lepidus Hall 



Tentaculites gracilistriatus Hall Productella spinulicosta Hall 



Styliolina fissurella {Hall) Strophalosia truncata Hall 



Euomphalus (Phanerotinus) laxus Spirifer mucronatus {Conrad) 



Hall Ambocoelia umbonata {Conrad) 



Bellerophon led a Hall Liorhynchus limitare {Vanuxent) 



Pterochaenia fragilis {Hall) Tropidoleptus carinatus {Conrad) 



Nuculites triqueter Conrad Crinoid stems 



Orthothetes arctostriatus Hall 



Ludlowville shale 



This formation embraces that part of the rock section extending 

 from the base of a 6 inch layer of soft limestone capping the Skan- 

 eateles shale and containing Strophalosia truncata 

 abundantly, to the Tichenor limestone. The term applied to this 

 member of the series is one of the earliest in the New York nomen- 

 clature and the occasion of its revival is explained in Museum 

 bulletin 63, p. 17-20, 1904. 



The shale is mostly fine, soft and evenly bedded, light to dark 

 bluish gray in color and but slightly calcareous. In the lower part 

 there are several thin, layers of limestone and calcareous concre- 

 tions are common. Next above the Strophalosia bed above men- 

 tioned, a stratum of concretionary limestone contains Nautilus 

 magister; another, 10 feet higher and 3 feet thick, contains 

 many trilobites; and a thinner one, 8 feet below the top of the 

 formation, contains Athyris spiriferoides in large numbers. 



The calcareous layers at some outcrops consist merely of rows 

 of broad flat concretions and their number and relative positions 

 vary greatly in different exposures; one or another may disappear 

 entirely and a new one come in at a higher or lower horizon. 



This formation is 60 feet thick in the southwestern corner of this 

 region and increases toward the east at an average rate of about 

 I foot a mile to Ontario county, where it is 125 feet thick. Farther 



