TITLES ANJ> ABSTRACTS OF PAPERS 173 



Discussion 



Mr. M. Y, Williams : The section along the barge canal at Rochester is, in 

 my opinion, the finest Lockport-Guelph section in eastern North America. The 

 thin, bituminous, Eramosa beds, described by Dr. William Logan as forming 

 the top of the Niagara (Lockport) formation at Guelph, have been shown by 

 Professor Chadwick to occupy a similar position at Rochester. The Lower 

 Shelby horizon at the base of the Eramosa beds at the Niagara Falls, as deter- 

 mined by Clarke and Ruedemann, corresponds with the horizon of a fauna 

 found by me at Guelph which contains Guelph species mixed with Lockport 

 species. The Upper Shelby fauna is in the true Guelph. 



Miss M. O' Con NELL : T have two questions to put to the writer of this paper. 

 The first is : Has he determined the origin of the carbonaceous material in the 

 Eramosa beds? The second is: What is the fauna of the beds? Have the 

 same eurypterids been found as Mr. Williams discovered in the Eramosa beds 

 of Ontario? 



Author's reply to Miss O' Conn ell : The dolomites above the true Lockport at 

 Rochester are all bituminous. The origin of the bitumen is probably not differ- 

 ent from that in the Onondaga, Falkirk, and other marine limestones. Col- 

 lecting in the Eramosa beds waits on the excavation. Eurypterid fragments 

 have, however, been obtained in the Upper Rochester (Homalonotus beds) at 

 Rochester. 



CAYUGAN WATERLIME8 OF WESTERN NEW YORK 

 BY GEOKGE HALCOTT CHADWICK 



(Abstract) 



Restudy and careful measurement of the uppermost Silurian (Ontaric) sec- 

 tions along the Onondaga escarpment from Bertie, Ontario, to the meridian of 

 Rochester, New York, show the following well characterized subdivisions, with 

 their approximate thicknesses : 



Akron dolomite (Grabau), subcrystalline, gray to brownish, 

 with Gyathophyllum hydraulicum 12 feet or less 



Buffalo cement bed, carrying eurypterids 6 feet 



Scajaquada dark shales and blockj^ waterlimes 8 feet 



At base the Bridgeburg horizon, with eurypterids. 



Falkirk dolomite, brownish and bituminous, below massive and 



often producing waterfalls 30 feet 



Carries a marine fauna, but eurypterids at base. 



O-atka beds, dark gray and shaly, with a l)locky watei-lime at 



base carrying eurypterids 20 feet or less 



These rest with an irregular, apparently disconformable, contact on the 

 ashen, pitted shales of the Camillus gypsite series at all localities where the 

 exposures go so low. 



The upper three members are found to be discontinuous across western New 

 York through pre-Onondaga erosion, and in their absence the Falkirk has been 

 partly or wholly referred to the Cobleskill. But they come in again at fairly 



