66 EDITORIAL 



physiographic data, and to allow fossils to be used for discrimi- 

 nation as well as for correlation, will, it is believed, be generally 

 approved. To meet the practical difficulties of mapping, litho- 

 logic units smaller than formations may, when sufficiently 

 important, be separately mapped as members or lenses. An 

 effort is to be made to conform in the general plan of mapping 

 to the logical categories of {a) sedimentary, {h) igneous, {c) met- 

 amorphic rocks. Surficial rocks of all ages are treated as a 

 subclass of sedimentaries, but are to be distinguished by patterns 

 in mapping on a genetic basis. The stratified rocks of the 

 Archean and Quaternary are given distinctive colors. There 

 are many other changes apparent when the old and new rules 

 are compared. 



Rules of nomenclature will not, unfortunately, be consistently 

 applied if the interpretation be left entirely to each individual 

 worker. To meet the necessities of the present case a Committee 

 on Geologic Names has been constituted, to consider and decide 

 the various difficulties which will inevitably arise in the varied 

 work of the Geological Survey. This committee is charged with 

 the inspection of all papers written by any member of the Survey 

 corps, and as part of its work keeps a complete card catalogue 

 of all formation names proposed or used in writings relating to 

 American geology. 



The closer co-operation of the various individuals and organ- 

 izations concerned in the advancement of geologic science in 

 this country is surely desirable, and much misunderstanding 

 and unproductive effort can certainly be eliminated if common 

 usage of geologic formation names can be brought about. While 

 a committee from the Survey, representing as it does only a part, 

 even though the larger part, of American geologists, can in the 

 nature of the case, have no authority over the publications of 

 geologists not belonging to its own corps, yet it is hoped that 

 general appreciation among geologists of the advantages of so 

 doing will induce individual and independent workers to avail 

 themselves of its functions, and to conform, when possible, to 

 the usages of the large body of their geological colleagues gov- 

 erned by its decisions. H. F. B. 



