TAXONOMIC RANK OF PENNSYLVANIAN 
GROUPINGS 
CHARLES KEYES 
When the title Pennsylvanian was first proposed for the upper 
subdivision of the general Carbonic section of America it was with 
the express purpose of designating the widely known Coal Meas- 
ures by a specific geographic name, and of implying a time value 
to the succession represented. In an unreasonable proneness of 
that day amounting almost to mania, of multiplying geographic 
and geologic terms and of giving new geographic titles to old 
lithologic units future contingencies of geologic taxonomy were 
entirely lost sight of, and the possibilities of some more refined 
nomenclature at no distant date were not taken into account. 
As thus suggested Pennsylvanian was intended to be a time- 
term equivalent of a rock series and its use in this manner was 
supposed especially to emphasize the naturalness and the necessity 
of a dual nomenclature which its author had then recently also 
strongly advocated. But there proved to be no urgent demand for 
duplicate sets of names, particularly when on every hand it was 
clearly recognized that a single set sufficed. The idea was received 
coldly. What a provincial rock series really needed was special 
definition in which the time element should find no place. The 
Coal Measures were found to be a rock sequence much too pon- 
derous to be cramped into provincial bounds. 
So ill-fitting was the new geographic title, taxonomically, that 
instead of clearly delimiting a terranal succession for all time, and 
becoming a world-wide time unit its proposition and use served 
only to throw the classification of the Coal Measures into utmost 
confusion. Taxonomic clarity was impossible. Being merely a 
place-name affixed to an old and not less indefinite section it 
carried with it all the objections possessed by the older designation 
without providing any new or advantageous attributes. It soon 
developed that it was without delimitation one whit clearer than 
that held by the older name the place of which it was intended 
to take. 
Raised later by some writers to high dignity with Periodic rank, 
and by others reduced to inconsequental serial position, it was 
