SUGGESTIONS CONCERNING NOMENCLATURE 391 



much good was accomplished in the way of coordinating the different 

 grades of units and in bringing the standard into harmony with the 

 progress of knowledge not only in New York but also to some extent 

 with stratigraphic facts acquired elsewhere in America. In viewing the 

 result it is to be noted that some of the old terms (Mohawk, Oswego, 

 and Niagara) have been raised to the rank of series, and one (Oriskany) 

 to that of a group. In two cases, however (Helderberg and Erie) — in 

 both for valid reasons — the original meaning is greatly restricted. It is 

 not my present purpose to discuss the merits of this revised classification, 

 except to say that enough has been learned in the past ten years, particu- 

 larly concerning the pre-Devonian part of the scale, to make another 

 revision highly desirable. New terms of all ranks must be intercalated, 

 and those in the "age or stage" column require discrimination by pro- 

 motion of some of the terms to the group column. 



Reverting to the perpetuation of old New York terms in some reason- 

 able approximation to the wide sense in which they were employed by 

 former generations of geologists, I shall briefly refer to those in which 

 my personal interests are chiefly concerned. Beginning below and going 

 up in the section, the first is the Chazy. This term was applied by 

 Emmons to a series of limestones in the Champlain Valley that we now 

 know to be not only much thicker than Emmons thought but it is also 

 divisible into three formations. Moreover, on comparison with middle 

 and southern Appalachian sections, it is found that in the Champlain 

 Valley the boundary between the middle and upper formations repre- 

 sents an important hiatus and that the interval between the top of the 

 upper and the base of the lower formation attains aggregates in historical 

 and time values entitling it to the rank of a series or epoch. It is with 

 this significance and in the form of Chazyan that I propose henceforth 

 to use this name. 



The second of these terms is the Black Eiver. As originally defined this 

 term included all the beds in the Black River Valley between the base of 

 the Lowville ("Birdseye") and the base of the Trenton. Later Hall con- 

 fined it to the "7-foot tier" at Watertown, New York, but in general 

 practice he and most other geologists applied the term to all beds between 

 the Lowville and the Trenton. Recently it was decided in conference 

 with the geologists of the New York Survey that inasmuch as a group 

 term is desirable the least confusion would be occasioned by revival of 

 the term in its original significance. In this sense, then, it is proposed 

 to extend the application of the name Black River from New York west- 

 wardly to the Mississippi Valley and southwardly to exposures of similar 

 rocks in the Appalachian Valley. 



