5© ROCHESTER ACADEMV OE SCIENCE. [J^"' ^^t 



in the Bulletin just mentioned, consequently it does not seem inap- 

 propriate to designate it the Genesee Section. 



The section crosses Allegany, Wyoming, Genesee and Monroe 

 Counties, and is in the main compiled from the records of wells near 

 Richburgh and Clarksville, Allegany Co., Castile and the Warsaw salt 

 region of Wyoming Co., LeRoyand Batavia, Genesee Co., and Brock- 

 port and Rochester, Monroe Co. Geologically the section commences 

 with the Olean conglomerate and its equivalents, which occur at or 

 near the summit of the highest hills in southern Allegany and Cat- 

 taraugus Counties, New York, and in northern McKean County, 

 Pennsylvania. Then it crosses New York State, passing through the 

 several terranes composing the Devonian and Silurian systems, and 

 terminates probably with the top of the Archean as shown by the 

 record of the Rochester well. 



The Genesee Section. 



In reviewing the history of the geology of western New York, 

 there seems to be special reason for carefully describing this section. 



In 1838 Professor James Hall, at that time State Geologist of the 

 Fourth District of New York, published a geological " Section 

 from the mouth of the Genesee River to Instantur, Penn." (') 

 Among the towns touched by this section are Rochester, Cale- 

 donia, Mt. Morris, Portage, Angelica and Wellsville, N. Y., thence 

 through Coudersport and Smithport to Instantur, It will be noticed 

 immediately that in a general way the New York part of this section 

 follows quite closely the direction of the one outlined for this paper. 

 It is interesting to note briefly the correlations made on this section 

 and in the accompanying description. The author says : " I consider 

 the rocks of the 4th District as belonging to the old red sandstone 

 and the carboniferous groups, and to be above the Silurian system of 

 Mr. Murchison." C) 



The Medina red sandstone was considered as belonging to the 

 *' Old Red Sandstone." The next general correlation is that of the 

 Upper Helderberg or Corniferous, which is called Carboniferous or 

 Mountain limestone. (') The remainder of the section is included 



(i.; 2d Ann. Rept. Fourth Geol. Dist., N. V. 



(2.) Ibid., p. 2gi. 



(3.) Ibid., p. 292, where it is stated that " Upon the Clypseous [Onondaga Salt group or Salina] 

 rocks lies the mountain limestone, commencing at Caledoni.i and near West Mendon, and extending as 

 far south as Avon." While on the section between Caledonia and York it is given as " Carboniferous 

 or Mountain Limestone." Also see foot note on p, 302 and p, 307. 



