1892. J PROSSER — THE GENESEE SECTION. 97 



erate to the Portage, all of which is Chemung, 1390' (Am. Geol. 

 Vol. VII, p. 165, pi. 4). 



c. Prof. Hall wrote : " The thickness of this group [Portage] on the 

 Genesee cannot be less than one thousand feet " (Geol. of N. Y., 

 Pt. IV, p. 238, also, see p. 217), In 1S40 Professor Hall gave the 

 thickness of the Cashaqua shale (lower part of Portage) as no' 

 (4th An. Rept. Fourth Geol. Dist. N. Y., p. 390), which is given as 

 the same in the final report [Op. cit., p. 227) ; but in the 4th An. 

 Rept. the Gardeau (Middle Portage) and Portage sandstones 

 (Upper Portage) are stated to " occupy a thickness of more than 

 1000 feet" {Op. cit., p. 392), which makes the thickness of the 

 entire Portage more than mo'. The vertical section of 1838 

 gave a thickness of 500' from the " olive shales and sandstones " 

 down to "bituminous shales" (2d An. Rept. Fourth Geol. Dist. 

 N. Y.) ; but this did not reach the base of the Portage and prob- 

 ably not its top as defined later. In 1879 it was given as "one 

 thousand feet or more in central New York " (Geol. Surv. N. Y., 

 Pal. Vol. V, Pt. II, p. 151). 



Dr. Clarke m 1885 stated : "In Ontario County the entire 

 series of Portage strata is very perfectly developed, reaching a 

 thickness of between 800 and 1,000 feet " (Bull. U. S. Geol. Surv. 

 No. 16, p. 36). This series is composed of about 365' belonging 

 to the Cashaqua and Gardeau subdivisions {Ibid., pp. 2,6, 37), 

 which are called Naples shales by Clarke, and about 600' of Port- 

 age sandstones {Ibid., p. 67, also, seep. 75). In the 4th An. Rept. 

 of the [N. Y.] State Geologist for 1884, Dr. Clarke gave the 

 thickness of the Naples shales in Ontario Co., as from " 350 — 400 

 feet" (Assembly Doc. No. 161 for 1885, p. 20) and the Portage 

 sandstones as from "600 — 700 feet" {Ibid., p. 21). 



SirWm. Logan in 1863 stated : "To the south of Lake Erie, in 

 New York, * * * The Portage and Chemung sandstones have 

 a thickness of 2,000 feet ; which increases to 3,000, farther to the 

 eastward " (Geol. Surv. of Canada, Rept. of Prog, from its com- 

 mencement to 1863, p. 389). Mr. Harris assigns a thickness of 

 1315' to the Portage in the Jamestown well (Am. Geol, Vol. VII, 

 p. 174, pi. 4) ; which would make the combined thickness of the 

 Chemung and Portage at least 2705' for the Jamestown region 

 and well {Ibid., pp. 165, 174, pi. 4). 



7, Proc. Roch. Acad, of Sc, Vol. a, June, 1892. « 



