STRATIGRAPHICAL GEOLOGY 
153 
tion of the Laramian problem in Colorado which for more than 
half a century so completely baffled all mining men and geologists. 
Laramian events are manifestly very much more important than 
has been commonly supposed. Keyes 
Pennsylvanian in Time Span. Notwithstanding the fact that in 
recent years the term Pennsylvanian, as a terranal title finds wide 
application, the question arises whether or not it has any intrinsic 
advantages over the older and more widely known term Coal 
Measures. There appear to be strong grounds for curtailed usage 
of the name, if not its complete abandonment in stratigraphy. 
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 
Measures by a specific geographic name, and of implying a time 
value to the succession represented. In an unreasonable prone¬ 
ness of that day amounting almost to mania, of multiplying geo¬ 
graphic 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 re¬ 
fined 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 sup¬ 
posed 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 re¬ 
ceived 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 
ponderous 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 car¬ 
ried with it all the objections possessed by the older designation 
