54 Cincinnati Society of Natural History. 
the Ohio River, as probably the equivalent of the Trenton. 
This early correct determination seems to have been lost 
sight of or disbelieved. A year later Prof. Hall* referred the 
main mass of strata occurring at Cincinnati to the Hudson 
River group. Some years later, 1862, Prof. Hall,t influenced 
by the studies of Sir William Logan, of the Canadian Geo- 
logical survey, concluded that the strata in the valley of the 
Hudson referred to the Hudson River group were older 
geologically than those referred to the same group farther 
west in New York and in the Mississippi valley and proposed 
to drop the term. But in 1877{ he concluded that he had 
been in error in dropping the term. 
In 1865 Meek and Worthen,§ then at work upon the 
geology of. Illinois, influenced by Hall’s discarding the term 
Hudson River group and the uncertainty prevailing as to 
just what this term stood for, proposed the term ‘‘Cincinnati 
group” for the blue limestone strata of Cincinnati and 
vicinity and their equivalents elsewhere. 
The second geological survey of Ohio began in 1869 a 
thorough examination of the geological structure of the State. 
The term “Cincinnati group” was adopted for the “Blue 
Limestone series” of the first survey. Partly for the reasons 
given by Meek and Worthen, but more especially because he 
considered that the blue limestone formed a homogeneous 
and indivisible whole in which there was a hopeless and 
inextricable confusion of Hudson and Trenton species, Dr. 
-J. S. Newberry,|| the chief of the survey, felt constrained to 
adopt their name. But as to this intermingling of Hudson 
and Trenton fossils, Dr. Newberry was mistaken; this sup- 
posed intermingling is due to the faulty identification of fos- 
sils incident to a time when paleontological science had not 
reached its present refinement and exactness. 
This conclusion of the geological survey seems not to have 
been acceptable in all quarters. While Mr. S. A. Miller at 
* Trans. Amer. Assoc. Geol. and Nat., 1843, pp. 267-293. 
+ Rep. Geol. Surv. Wisconsin, I, 1862, p. 47 (foot note) and p. 443. 
t Note upon the history and value of the term Hudson River group in American 
geological nomenclature. Proc. Amer. Assoc. Adv. Sci., XXVI, 1877, pp. 259-265. 
Zz Proc. Acad. Nat. Sci., Philadelphia, 1865, p. 155, and Geol. Illinois, I, 1866, p. 136. 
| Geol. Surv. Ohio, I, 1873, p. 117. 
6 
