ROCHESTER ACADEMY OF SCIENCE. [Jan. ir, 



known with certainty west of Manchester, Ontario Co." (Rept. 

 State Geol. [N. Y.] for 1884, p. 10). 



The presence of the Lower Helderberg limestone in this sec- 

 tion also seems doubtful. The Waterlime or Hydraulic limestone 

 of western New York was stated by Professor Hall to lie beneath 

 the Lower Helderberg waterlime of eastern New York and he 

 called it the fourth or upper division of the Onondaga Salt group 

 (Geol. N. Y., Pt. IV, pp. 128, 129, 141 ; also, see sections 55 and 

 56 on p, 139). Dr. T. Sterry Hunt in describing the geology of 

 the Ontario peninsula said : " Here are found non-fossiliferous 

 strata, having the character of the so-called Waterlime beds, 

 which belong to the summit of the Salina formation " (Am. Jour. 

 Science, 2d ser Vol. XLVI, 1868, p. 359). Professor Hall's map 

 of 1874 giving the distribution of the Niagara and Lower Held- 

 erberg formations does not give any Lower Helderberg west of 

 Ontario Co., while in the sections the " Water-lime formation " is 

 given as intermediate between the Lower Helderberg and Onon- 

 daga Salt group (27th An. Rept. N. Y. State Mus. Nat. Hist., 

 1875, map, and see p. 128). The same position was assigned to 

 the Water-lime by Professor Hall in 1859 (Geol. Surv. N. Y., Pal- 

 aeontology, Vol. ni, Pt. I, Text, p. 385), although the author was 

 inclined to refer it to the Onondaga Salt group {Ibid., p. 387). 

 The latter view is also taken by Dr. Clarke in 1889 (8th An. Rept. 

 State Geol. [N. Y.] for 1888, p. 81). Finally, Ashburner stated : 

 " The Buffalo cement bed [Water-lime of western N. Y.] is 

 one of the top strata of the Salina, and does not belong to the 

 Water-lime group [Lower Helderberg], as popularly supposed " 

 (Trans. Am. Inst. Min. Eng., Vol. XVIII, 1890, p. 301. Also, 

 see Ashburner in ibid.. Vol. XVII, p. 399, foot note f ). On the 

 contrary Professor Dana refers these beds to the Lower Helder- 

 berg (Man. of Geol., 3d ed., pp. 235, 236). 



Hall's "vertical section" of 1838 assigned a thickness of 400' 

 to the " gypseous slates and marls," which agrees very closely 

 with the limits of the Onondaga Salt group (2d An. Rept. Fourth 

 Geol. Dist. N. Y. ; also, see pp. 303-307 for a description of the 

 rocks). Dr. Clarke gave the thickness of the Salina for Ontario 

 Co. as "probably between 600 and 700 feet " (Rept. State Geol. 

 [N. Y.J for 1884, p. 10). It thins slowly to the west, having a 

 thickness of 475' in the Buffalo well (Ashburner, Trans. Am. Inst. 

 Min. Eng., Vol. XVII, p. 402). Professor Hall wrote Ashburner : 



