916 



SCIENCE 



[N. S. Vol. XXXIX. No. 1015 



tion. is desirable we may revert to the second 

 question. Vanuxem" introduced the name 

 Medina sandstone into the literature in 1840, 

 applying it to beds " called in former reports 

 the red sandstone of Oswego." A much fuller 

 description of the Medina sandstone was given 

 by Vanuxem in 1842. ^ The formation is 

 fully described in this report from exposures 

 occurring in the Third District of New York 

 to which Vanuxem's work was officially con- 

 fined at that time. The name Medina which 

 was given to it was taken, curiously enough, 

 from a town, about 100 miles west of the 

 western limit of Vanuxem's field of work. 

 Whether we consider the type section to be at 

 Medina or in the third district where the par- 

 ticular section and exposures of the forma- 

 tion described are located, we must go to the 

 latter region to discover just what is included 

 in the term Medina sandstone. It is stated 

 by Vanuxem to include sandstones lying be- 

 tween the Clinton above and the Oswego sand- 

 stone below. It is noteworthy that Vanuxem's 

 definition of Medina contains no reference to 

 shale. All of the occurrences of the Medina 

 sandstone which he described in the third 

 district are described as sandstone. The 

 Medina as later defined by Jas. Hall' in 

 western New York is mainly a shale forma- 

 tion comprising the 100 feet of sandstone just 

 below the Clinton together with several hun- 

 dred feet of red shale lying between this sand- 

 stone and the Oswego sandstone. The ex- 

 planation of this apparent discrepancy between 

 the two definitions appears to lie in the fact^ 

 that the upper or sandstone part of Hall's 

 Medina extends considerably further to the 

 east than the lower or shaly part. If Hall's 

 lower Medina (Queenston of Grabau) does 

 not extend a,s far east as the section described 

 by Vanuxem then the original definition of 

 Medina includes only the upper part of the 



6 Geol. Rept. New York, 4th Ann. Rept. of the 

 Geol. Surv. of the Sd Dist., 1840, p. 374. 



7 Geol. of N. T., Pt. III., 3d Dist., 1842, pp. 

 71-74. 



8 Geol. of New York, Pt. IV., 1843, pp. 34-57. 



9 Handbook New York State Mus., No. 19, Table 

 2, 1912. 



beds ascribed to it by Hall, or that part to 

 which this name is restricted by Grabau. 

 Should this inference prove to be true, then 

 Grabau's usage of Medina is really a return 

 to the original meaning, and not a restriction 

 of it. In this case then it will be in order to 

 consider whether any good reason can be 

 offered for following the usage of Jas. Hall 

 which makes the term include some hundreds 

 of feet of beds which Vanuxem's definition 

 excluded. 



It is proposed here, however, to consider the 

 question on the assumption that the applica- 

 tion of the name Queenston to the shaly, and 

 Medina to the sandy part of Hall's Medina 

 was an emendation of the original usage. We 

 may first consider in doing this some of the 

 circumstances which may justify or necessi- 

 tate emendation of formation names. Under 

 the rules of nomenclature formulated by the 

 United States Geological Survey for the 

 guidance of its members it is stated that 

 " each formation shall contain between its 

 upper and lower limits either rocks of uniform 

 character or rocks more or less uniformly 

 varied in character, as, for example, a rapid 

 alternation of shale and limestone."^" The 

 application of this rule to the sediments in- 

 cluded in Hall's Medina would not permit 

 the use of the name in a formational sense, 

 since the upper hundred feet and the beds 

 below are entirely diverse in character, the 

 latter being almost entirely a red shale, and 

 the former chiefly a sandstone terrane. This 

 lithologic difference between the upper and 

 lower terranes, however, would not necessarily 

 militate against the use of Medina in the 

 group sense. It is in this sense that the 

 name has been used lately by the N. Y. State 

 Geological Survey^^ and by the U. S. Geolog- 

 ical Survey.^- There is, however, another and 

 very serious objection to using the term in the 

 group sense. Until recent years the upper and 

 lower divisions of the Medina were supposed 

 to represent the basal part of the Silurian. No 



10 24th Ann. Eept. District U. S. G. S., p. 23, 

 1903. 



11 Handbook 19, 1912. 



12 Folio U. S. G. S., No. 190, 1913. 



