1 879-] The Paleontologist. 27 



GEOLOGICAL NOMENCLATURE. 



{TIic Cincinnati Group — The "Hudson River Group.") 



At a special (called) meeting of the Cincinnati Society of Natural History 

 January 23, 1879, a committee was appointed to report on the above subject; 

 and at the same meeting the committee made a report, stating : 



"That the fossils found in the strata, for twenty feet or more above low water 

 mark of the Ohio River, in the First Ward of the City of Cincinnati, and on 

 Crawfish Creek, in the eastern part of the city, and in Taylor's Creek, east of 

 Newport, Ky., at an elevation of more than fifty feet above low water mark in 

 the Ohio River, indicate the age of the Utica Slate Group of New York."-'- 



The only evidence here produced to prove such "indication'' is the occur- 

 rence of a single identified species, {Triartlirus becki,) and that is found in all 

 three of the New York groups — the Trenton, Uti:a Slate and Hudson River — 

 the other species mentioned as in the specified limits are unknown in the New 

 York groups. 



The Report further says : 



" Above the range of the Triartlirus becki, the fossils, as well as the position of 

 the rocks, indicate the age of the Hudson River Group of New York, and we have 

 no hesitation in so referring them, and entertain no doubt of the correctness 

 of the reference." 



No evidence whatever is here offered in support of the "reference" of the 

 rocks in question to the Hudson River Group of New York. And the com- 

 mittee come to 



"The conclusion, * -•" that all the Lower Silurian Rocks, which we have 

 had under consideration, are to be referred to the Trenton, Utica Slate and 

 Hudson River Groups, and that the name 'Cincinnati Group' should be dropped. " 



This is, certainly, a summary way of setting aside the name for an important 

 series of rocks — a name now generally accepted and adopted, and published in 

 many Test Books and Reports of Geological Surveys, and known over the world. 



Prof. James Hall says: (Pal. N. Y. Vol. i) in reference to this matter: 



"At the west, particularly in Ohio and Indiana, the augmentation of calca- 

 reous matter has made it impossible to draw any line of demarkation which shall 

 correspond with the three divisions so obviously marked by the lithological char- 

 acters in New York." 



Every collector in the Cincinnati Ciroup knows that particular species of fos- 

 sils are confined to well defined horizons, and not found above nor below, which 

 would require the making of a number of groups of the Cincinnati Strata, 

 should the rule proposed by the committee for establishing the name, Utica 

 Slate Group, be adopted. 



If anything is shown in favor of dropping the name, " Cincinnati Group.'' and 

 adopting the New York nomenclature, it would seem more appropriate to take 

 the Trenton (iroup, not Utica Slate, nor Hudson River; the proportion of Tren- 

 ton fossils in the Cincinnati being more than as two to one of the Utica Slate or 

 Hudson River. But the Report .says, correctly : 



"The Trenton Grou|) is not ex])Osed at Cincinnati, nor at any point in Ohio 

 west of the city." 



*It is difficult to make out from this how much space is intended to be included in 

 the proposed division. 



