56 THE JOURNAL OF GEOLOGY. 



which accompanies Lyman's protest, I am at present of opinion 

 that the needs of geologists are better served by Newark than by 

 New Red, Jurassic, Jurassico-Triassic, or Rhsetic. 



It may be assumed that there is no difference of opinion as 

 to the propriety of giving local geographic names to the minor 

 stratigraphic units. Such is the modern practice of most geo- 

 logical surveys, and it has the sanction of the International Con- 

 gress of Geologists. Lyman, too, in the paper cited, introduces 

 Pottstown shales, Lansdale shales, Norristown shales, Perkasie 

 shales and Gwynedd shales as the names of newly recognized 

 formations in eastern Pennsylvania and the contiguous parts of 

 New Jersey, deriving the distinctive word in each case from the 

 local geography. The stratigraphic units thus distinguished are 

 all parts of the larger unit to which Redfield applied the local 

 geographic name "Newark." 



But Lyman protests against the use of the local name for the 

 larger unit. It is not entirely clear to me whether he holds that 

 the larger unit should have no name, or that it should not have a 

 local name, or only that it should not receive the particular local 

 name ; and I therefore find it easier to state the basis of my own 

 opinion than to discuss his view. 



I. In my opinion the larger tinit should have a7i mdividtial 

 name. — In the nomenclature of stratigraphy, as in language gen- 

 erally, it is advantageous to avoid paraphrases by giving a short 

 name to every concept which needs frequently to be expressed. 

 That for which Redfield proposed the name " Newark group "^ is 

 a stratigraphic integer, so definitely limited in nature that its 

 individuality has been recognized in the literature of a half cen- 

 tury. In the paper just referred to it is distinctly recognized by 

 Lyman, who calls it in one place " the older Mesozoic rocks of 

 New Jersey," and elsewhere " the older Mesozoic," " the so-called 

 New Red," "the New Red beds," "the New Red." Each of 

 these terms is used as a name rather than as a description ; even 

 the long phrase " the older Mesozoic rocks of New Jersey " is 

 not a definition, for it is made to cover rocks, for example, the 



'Am. Jour. Sci., 2nfl sen, Vol. 22, 1856, p. 357. 



