June 19, 1914] 



SCIENCE 



915 



SPECIAL ABTICLES 



WHAT DOES THE MEDINA SANDSTONE OF THE 

 NIAGARA SECTION INCLUDE ? ^ 



Most geologists will agree, if stated as an 

 abstract proposition, that a primary essential 

 of any system of formational nomenclature 

 is stability. In concrete examples, however, 

 geologists display a marvelous facility in for- 

 getting the importance of such stability or in 

 ignoring any rules which might bring it about. 

 This is well illustrated by the present status 

 of the term Medina sandstone. In papers 

 which have been read before the Geological 

 Society of America during the last two years 

 not less than three distinct meanings have 

 been given to this term. The inconvenience 

 of using any unit of measure which fluctuates 

 in length from year to year would be no 

 greater than that of using formation names 

 for the geologic scale, which may differ by 

 hundreds of feet in the thickness of beds in- 

 cluded, according to the date or the individual 

 author concerned. One can, of course, and in 

 the present chaotic state of geological nomen- 

 clature generally does, in using a formation 

 name, indicate whether he accepts Wm. Jones's 

 or John Brown's definition of the formation. 

 He may too have recourse to the booklets of 

 formation names issued at intervals by some 

 surveys, and ascertain what is the most fash- 

 ionable length during the year in which he is 

 writing for the formation in question. While 

 these are possible and at present apparently 

 necessary methods of indicating what one 

 means when using a formation name, surely 

 it would be better to adhere to a standard 

 definition as we do for such terms of measure 

 as foot and meter. Such a standard definition 

 of a formation, of course, in no way precludes 

 its subdivision as the progress of knowledge 

 concerning it may dictate, accompanied by 

 new names for the new sub-units. In the 

 case of names which seldom reappear in 

 the literature the inconvenience of changing 

 meaning is comparatively small, but fluctua- 

 tion in the meaning of such a term as Medina 



1 Published with the permission of the Director 

 of the Geological Survey of Canada. 



sandstone which occurs in most text-books on 

 geology and in innumerable geological papers 

 must lead to endless confusion. During the 

 last decade a number of papers, perhaps the 

 majority of those dealing with the Silurian of 

 western New York, have made the term 

 Medina include only the 100 feet of bed3 

 which are chiefly sandstones immediately pre- 

 ceding the Clinton; the others have included 

 these and 1,100 feet of red shales below them 

 as well in this formation.^ Some inquiry into 

 the reason for this wide diversity of usage 

 and suggestions regarding the limitation of 

 this term which the rules of nomenclature 

 seem to indicate appear to be in order.^ 



These rather surprising fluctuations in the 

 thickness of the Medina sandstone in the same 

 section began with Grabau's* and Chadwick's^ 

 proposals to restrict the name to the upper 

 100 feet of Hall's Medina sandstone, the lower 

 1,100 feet being named the Queenston shale 

 by Grabau. In raising the question whether 

 there were good grounds for restricting the 

 term to the upper beds to which the sandstone 

 is almost wholly confined, and giving to the 

 lower shaly portion a new name, we are con- 

 fronted by two subsidiary questions. (1) Is it 

 ever permissible or desirable to restrict or 

 redefine the name of a formation? (2) Was 

 the Jas. Hall usage of Medina sandstone which 

 Grabau's proposal supplanted identical with 

 the application given the name by Vanuxem, 

 who first used it? Examples both of contrac- 

 tion and expansion of the original meaning of 

 formation names might be cited from the 

 papers of various geologists. Whether the 

 practise is approved or censured, there is abun- 

 dant precedent for emendation of the original 

 meaning of geologic names. 



Before considering some of the conditions 

 under which in the writer's judgment emenda- 



2 Bull. N. y. State Mus., No. 114, p. 10. 



3 The writer wishes to acltnowledge the privilege 

 of examining before preparing this paper a manu- 

 script by Dr. E. O. Urieh which treats, among 

 others, the question here discussed. 



4 Science, Vol. 27, April 17, 1908, p. 622. 



5 Science, Vol. 28, September 11, 1908, pp. 346- 

 348. 



