Lesley.] ^74 [April 6, 



The discussion in New York respecting the lower limit of the Catskill 

 formation (recently settled by the proper placing of the Oneonta sand- 

 stone) has always left the great Catskill formation unaffected. So in 

 Pennsylvania, the 100' of transition beds at the bottom of the Ponent and 

 at the top of the Vergent, do not affect in the least the broad fact that 

 Ponent is "Catskill" and Vergent is "Chemung." No palsontological 

 discoveries can ever alter these established relationships. 



The discovery of Catskill fish-forms down in the Chemung has no more 

 bearing on the name "Catskill" than it has on the name Ponent; for 

 "Catskill" and Ponent are merely synon\'ms for the 3000' -j- of red and 

 gray sanc's and shales of the Catskill-Pocono-Alleghany mountain range 

 which present a continuous outcrop from the Hudson to the Potomac. 



The discovery of Catskill fish-forms down in the Chemung merely adds 

 one more item of evidence to the now almost accepted conviction that the 

 task of devising geological names of the first and second order cannot 

 safely be enti'usted to palaeontologists, but that they must limit their 

 function as namers of strata to names of the third and fourth order, as the 

 geologists of the continent of Europe have been content to do for some 

 years back, designating the groups of beds in a subdivision of a forma- 

 tion by some characteristic fossil form ; as, for instance : — Trias ; 1. 

 Gr^s bigarre ; 1. b. Gresa Woltzia. The fact is becoming patent to all eyes, 

 that the occurrence of special fossil forms in a rock is no evidence of the 

 exact age of that rock until after its exact age has been settled topographi- 

 cally or structurally. 



If then the new fish-form be a Catskill fish found in Chemung rocks, 

 it will not make the upper part of the Chemung, Catskill. It merely 

 happens that a Chemung fish is also a Catskill fish. And so of any other 

 fossil form discovered under similar circumstances. 



Mr. Lesley added that the discovery of the Kingsmill White Sandstone 

 fossils by Prof Claypole is important for the future settlement of the 

 question : What becomes of the Catskill formation going west into Western 

 New York, Ohio and Michigan ? If we could trust the evidence of fossil 

 forms for establishing a lithological horizon — if we were sure that there 

 were an immovable horizon extending more than 500 miles (S. E. and N. 

 W.) characterized by Hall's Eaompludus depressus, and Cypricnrdin con- 

 tractu, Winchell's Edmondia (Bquimarginalis, and Shumard's AUorisma 

 Hannibalensis — and if this horizon be seen at Marshall in Michigan just 

 under the Goal measures, at Panama in Western Ncav York considerably 

 below the Venango Oil measures, and in Perrj^ County, Middle Penns}*!- 

 vania, just below the bottom of the great Catskill formation — everybody 

 who believes in this kind of evidence must accept tlie conclusion that 

 there is a time gap in the Michigan and Northern Oliio section to be 

 measured by many thousand feet of Pennsylvania strata, the majority of 

 which are Catskill ; and that this gap happens between the "Marshall 

 grit" of Michigan and the next overlying strata. 



