THE OHIO EQUIVALENTS. 351 



directly overlies the Trenton limestone. At Hamilton the same driller re- 

 ported the boundary at forty feet, and the black shale was here reduced to 

 thirty-seven feet, according to his record. From these and similar facts it 

 appears that the Utica shale is much reduced and altered as it approaches 

 the Ohio valley, and is finally lost by the overlap of the Hudson River shale 

 in this portion of the state and to the southward. 



A comparison of the fauna as obtained at Lorraine with that of the Cin- 

 cinnati section shows nearly all of the Lorraine species at Cincinnati; also, 

 that they have relatively the same range in the section. This comparison 

 has been made in a tentative way, but so far as it has gone it shows a sur- 

 prising equality in range of species in the two sections. Comparing the 

 section at Lorraine, as I have already stated, the fauna of the passage-beds 

 from the Utica shale zone is almost identical with that of the zone discovered 

 near Albany, which, from the general character of the strata in the valley of 

 the Hudson, I presume to be at about the same stratigraphic horizon in the 

 section. 



Value of the Term. 



The use of the name Hudson River group has been attended with more 

 or less uncertainty ever since it was promulgated by the geologists of the 

 New York Survey. Of the board composing that .Survey, Dr. Mather, Mr. 

 Vanuxem, and Professor Hall favored the use of the terra, while Dr. Emmons 

 used Lorraine and Mr. Conrad, Salmon river, for the same series of rocks- 

 This uncertainty was further increased in 1862 by the statement of I'm lessor 

 Hall that the term Hudson River group could not be extended to include 

 the rocks of central and western New York and the Ohio valley between the 

 Trenton limestone and the Upper Silurian rocks. Under the influence of 

 Professor Hall's withdrawal of the term, Messrs. Meek and Worthen pro- 

 posed, in 1865, the use of the name Cincinnati, saying: 



"As it is now acknowledged that the rocks along the Hudson river valley, to which 

 the name ' Hudson River group' has been applied, belong, as long maintained by Prof. 

 Emmons, to a different horizon from the so-called Hudson River recks of western 

 New York and the states further westward, it seems to be an awkward misnomer to 

 continue to apply the name 'Hudson River group ' to these western deposits. In Bub- 

 divisions, it is true, have received various lithological names, such as Utica Slate, 

 Frankfort Slate, Lorraine Shale, etc.; but as each of these names w i 11 probably be 

 always directly associated in the minds of geologists with the particular subdivision 

 to which it was originally applied, while neither of them is applicable to the lithe- 

 logical characters of the whole series, we cannot, without creating confusion, bo ex- 

 tend its signification."* 



The term Cincinnati group was adopted by the geologic surveys of Illi- 



* Proc. Acad. Nat. Sci. Phil., vol. 17, 1866, p. I 

 XLVI— Bull. Geol. Soc. Am., Vol. l, 188». 



