to the Ohio Shale Problem. 179 



be cited as evidence tending to prove that the top of the Cha- 

 grin is in places at least not older, if indeed it is not slightly 

 younger, than the highest beds of the Chemung in Pennsyl- 

 vania and New York. 



Supposed Genesee fossils in the basal part of the Ohio shale. — 

 Fossils which have been compared or identified with species 

 found in the Genesee shale of New York have been frequently 

 listed and described as from the basal part of the Ohio and 

 New Albany shales. I do not wish to deny that fossils having 

 such affinities occur in these black shales. Indeed I have 

 often seen them there. But I do wish to recommend caution 

 in correlating all such occurrences as Genesee. The age 

 relations of black shale faunas generally are notoriously decep- 

 tive. If space were available I would cite several most 

 instructive examples. The precedent of these fully established 

 cases of persistence of black shale faunas — in two instances 

 proving a range from well down in one system to a position 

 well up in the next — would fully warrant throwing out as 

 inconclusive all the fossil evidence yet cited from the Chat- 

 tanoogan series as indicating the Genesee age of the beds from 

 which such fossils were procured. But I am not inclined to 

 do this at the present time. I am only recommending caution 

 and close inspection of not only the specimens but also of 

 every kind of evidence that may be used in stratigraphic 

 correlation before it is decided that any Linguloid or any 

 Leiorhynchus, JPrioniodus, or Sporangites is really the Gene- 

 see occurrence of the species to which they seem to belong 

 and not some later or earlier occurrence of the same. 



Is there any warrant for citing the " Huron" fauna and 

 flora as Devonian ? — I wish to ask, how came the Huron fos- 

 sils to be called Devonian ? The answer is obvious enough 

 when we consider that the beds containing them were, as I 

 believe, erroneously regarded as underlying the Chagrin with 

 its undeniably Devonian fauna. Under this probable miscon- 

 ception the Huron fishes in particular were, without evidence 

 of their own, simply referred to the Devonian column as soon 

 as each was discovered. I am aware, of course, that for more 

 than sixty years most geologists correlated the black shale of 

 Kentucky as Genesee or earlier ; but there were also others 

 who held a different view and made it younger. So after all 

 it was not until the Ohio geologists placed the Chagrin above 



presence of this— otherwheres in the Ohioan province, strictly Waverlyan — 

 genus in beds underlying the Cleveland shale, on a firmer basis than 

 heretofore. But it is to be understood that these Jefferson specimens have 

 nothing to do with those mentioned many years ago by Newberry as having 

 been found in a similar position at Bedford. All agree now that the latter 

 came out of some Bedford float which had gone down stream. 



