42 W. A. Yerioiehe — Correlation of the 



sentative of the third YenaDo^o oil sand. This member has a 

 strong development in Cattaraugus and Allegany counties of 

 j!^ew York, but is rather difficult to trace over the intermedi- 

 ate area. Still Mr. Butts in this connection reports finding 

 " a ledge of conglomerate, 3 feet thick and apparently in 

 place," and concludes that: " If in place this lies near the hori- 

 zon of the Wolf Creek conglomerate."* He also states that 

 the Panama conglomerate appears to lie at about the same 

 horizon. I. C. Whitef considered the Panama conglomerate 

 as the equivalent of the third Yenango sand. This correlation 

 then bears out very well the conclusions stated above. 



Knapp formation : The name Knapp was proposed by 

 Glenn. :{: It has been traced south from Allegany County, 

 N. Y. to TTarren County in Pennsylvania by Chas. Butts and 

 he describes it here as consisting of '' three members, a con- 

 glomerate 20 to 30 feet thick at the bottom, a bed of shale and 

 thin fine-grained sandstone 10 to 40 feet thick in the middle, 

 and a conglomerate 20 to 60 feet thick at the top." The maxi- 

 mum thickness of the formation is given as 120 feet. An 

 older and perhaps better known name of this formation is 'sub- 

 Olean conglomerate.' Mr. Butts also states that it has been 

 commonly regarded as the equivalent of the Shenango sand- 

 stone but that the latter in reality overlies the former by 350 

 to 400 feet and has been removed from this region by erosion. 

 In another paper the writer has indicated his reasons for corre- 

 lating the Knapp formation with the first Yenango sandstone. § 



Thus it will be seen that the Knapp and Conewango may be 

 very logically treated as a unit as they correspond to the 

 Yenango oil sand group farther west and south. Girty with 

 his intuitive farsightedness saw this relationship at an early 

 date and proposed for them the series name of Bradfordian. 



Bradfordian : In a paper on the Paleozoic of Ohio and 

 Pennsylvania|| G. H. Girty proposed Ihe term Bradfordian 

 and delimited it as follows : " The series of rocks and faunas 

 in southwestern New York which overlie the true Chemung 

 inclusive of the sub-Olean conglomerate, recently assigned by 

 Prof. J. M. Clarke to the Carboniferous, really lie below the 

 base of the Carboniferous system as at present recognized in 

 this country, just as they lie above the Chemung beds, the 

 recognized top of the Devonian. This series, hav^ing an 

 approximate thickness of 500 feet, represents an interval not 

 provided for in the geological time scale, and for it the term 

 Bradfordian is proposed. This term which will rank with 



* U. S. G. S. Folio No. 172, p. 27. 

 f 2d Pa. Geol. Surv. Kept., Q-", 1881, p. 112. 

 X Rept. N. Y. State Paleont. 1902, p. 980. 

 j5This Journal, vol. xlii, p. 55, July 1916. 

 II Science, vol. xix, p. 24, 1904. 



