154 
STRATIGRAPHICAL GEOLOGY 
without providing any new or advantageous attributes. It soon 
developed that it was without delimitation one whet 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 inconsequential serial position, it was 
really neither. A time signification of periodic proportions was 
not possible because it would have to be applied in world-wide 
sense. For the present, at least, and perhaps for all time, the 
term cannot be expected to hold time evaluation. With a pro¬ 
vincial serial rank it leaves no room for real series, and there are 
many. An intermediary “group” is not only unnecessary, but bur¬ 
densome and serves no useful purpose. In our Continental In¬ 
terior for example, there are no less than five rock series which 
already well established must eventually be accepted as valid. 
All are to be resolved out of the Coal Measures, or so-called 
Pennsylvanian section. 
In the larger sense the time-value of the Pennsylvanian is much 
too long; in the lesser sense it is much too short. According to 
most approved canons of modern nomenclature the title seems to 
have no taxonomic claims. In view of all of these circumstances 
the old name still has useful mission; the later term none. It is 
today one of the chief drawbacks to taxonomic progress in this 
country, for the principle is far-reaching. Until the term is 
dropped from our system of nomenclature the diastrophic aspects 
of the Coal Measures stratigraphy are likely to be continually mis¬ 
interpreted, and true advancement made impossible. 
Superior Paleozoics of Rio Grande. Marine beds which make 
up the Carbonic sequence of southwestern United States consti¬ 
tute one of the great sections of the American continent. On the 
Rio Grande this succession of Carbonic rocks is the most com¬ 
plete known. A great thickness of strata, 4,000 feet or more, 
appears to be the youngest Paleozoics present in this country and 
perhaps in the world. 
In a recent review of the widely scattered and indifferent litera¬ 
ture on the ore deposits of New Mexico there are prefaced sketch¬ 
es of the geologic features of the region. The Carbonic succes¬ 
sion comes in for radical rearrangement, and proposals of new 
