GEOLOGY OF THE AUBURN-GENOA QUADRANGLES 21 



Ludlowville shale 

 Next above the Skaneateles beds there are about 25 feet of Hghter 

 colored, sandy shales somewhat calcareous and harder than the beds 

 below and above. This band is abundantly fossiliferous containing 

 many large brachiopods and cyathophylloid corals. It is continuous 

 across this quadrangle and westward, with an increasing proportion 

 of calcareous matter and fossils to Ontario county, appearing at Cen- 

 terfield, 5 miles west of Canandaigua as a distinct stratum of limestone 

 largely composed of corals. 



It is succeeded here by about 100 feet of soft dark shales similar in 

 character to the Skaneateles and containing a somewhat similar fauna. 



The upper beds gradually become more sandy, lighter colored and 

 fossiliferous. Thin calcareous lenses, masses of crinoid stems and 

 other fossils occur and there are many small concretions. 



The formation is terminated at the top by a continuous layer of 

 crinoidal limestone, formerly the " encrinal limestone," now known 

 as the Tichenor limestone. 



These beds were first designated Ludlowville shales by Professor 

 Hall in his report on the geology of the Fourth District (for 1838) 

 1839. 



Exposures. The upper and more fossiliferous part of this 

 formation is exposed along the east side of the Lehigh Valley Rail- 

 road for nearly a mile in the vicinity of Portland (or Shurger) 

 point, and also to the thickness of 2^ feet in the north bank of 

 Salmon creek a mile below Ludlowville. It is below the lake level 

 from the north side of Myers point to Atwaters, but is abundantly 

 displayed in the cliff and ravines along the lake shore and railroad, 

 almost the entire distance between Atwaters and Stony point, the 

 upper beds being most conveniently exposed in the vicinity of King 

 Ferry, and the lower fossiliferous band at Willetts and Stony point. 



The soft shales of the middle portion of the formation appear in 

 walls of the ravine of Payne's creek and the upper beds capped by the 

 Tichenor limestone at the falls. 



There are many outcrops of Ludlowville shale in the small ravines 

 north of Aurora and on the crest of the ridge 2 to 4 miles south of 

 Fleming. The lower beds are finely exposed along the road 3^ mile 

 southwest from Wykoff and the ravine at Ensenore displays almost 

 the entire Ludlowville section and there are fine exposures along the 

 railroad north and south of Ensenore. 



The fauna of the Ludlowville shale is a very large one. For list 

 of species see State Museum Bulletin 63 under Canandaigua shale 

 and Bulletin 99. 



