Related Formations, 



9 



Prof. Edward Orton on page 369 of the first volume of the 

 Geology of Ohio 1873, says : 



"It will, however, be shown to be probable that the lowermost 

 beds of Cincinnati are the proper equivalent of the Utica slate ; in 

 other words, that these shales and limestones were growing here, 

 while the black L tica shales were in progress of deposition in Eastern 

 Xew York." 



Also on page 398, in referring to the presence of Triarthrus JBecki, 

 he says : 



"Some interest is connected with the occurrence of this fossil here, 

 because it is counted quite a characteristic fossil of the Utica shale, 

 of Eastern Xew York. It belongs, however, in the Trenton of the 

 same region, so that no parallelism of formations is effected by this 

 trilobite, which other fossils are unable to establish. The most that 

 can be said in regard to it, is, that it suggests the low water beds of 

 Cincinnati as the equivalent of the Utica shale." 



The specimens of Triarthrus Becki found in the Trenton limestone 

 of Xew York occur in the upper portion of the formation in what may 



Ohio river, indicate the age of tbe Utica slate group of Xew York. A fauna is 

 represented in these rocks, that is not found above or below them. Within this 

 range, we find the Triarthrus Becki, Leperditia Byrnesi, Leptobolus lepis, Batho- 

 trephis ramulosa, and several species of graptolites, criuoids, brvozoans, and 

 brachiopods, that seem to be confined within its limits. Moreover, the brown 

 slates and greenish blue shales and concretionary nodules give a lithological 

 character to the strata, which distinguish them from the strata both above and 

 below. From the evidence thus furnished by the lithological character of the 

 strata, and the distinct character of the fossil remains, we refer all the strata 

 containing the Triarthrus Becki to the age of the Utica slate group of New York. 



" Above the range of the Triarthrus Becki, the fossils, as well as the position of 

 the rocks, indicate the age of the Hudson River group of Xew York, and we have 

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

 the reference. 



" The fossils from Paris, Lexington, the High Bridge over the Kentucky river, 

 and from other places in Kentucky, as well as the lithological character of the 

 strata, furnish abundant evidence of the existence of the Trenton group over an 

 extensive tract of country, in that state. In the state of Kentucky, we have the 

 Trenton, Utica slate and Hudson River groups well represented, and the rocks 

 have a northerly dip from Paris and Lexington, toward the Ohio river, * * * 

 The conclusion is, that all the Lower Silurian rocks, which we have under 

 consideration, are to be referred to the Trenton, Utica slate and Hudson River 

 groups, and that the name ' Cincinnati group ' should be dropped, not only be- 

 cause it is a synonym, but because its retention can subserve no useful purpose 

 in the science, and because it will, in the future, as in the past, lead to erroneous 

 views and fruitless discussion. And we would add that so far as any investiga- 

 tions of these rocks have been made, they have not led to any further or other 

 subdivisions than those which we have adopted, and which have been so thor- 

 oughly and firmly established by the geologists of the state of Xew York.^" 



1 Report of special meeting of the Cin. Soc. Nat. Histy., Jany. 23d, 1879. 



Tram. x. 2 



