In organizing the general geologic work, it became necessary, first, to
consider what had already been done in various portions of the United
States; and for this purpose the compilation of a general geologic map of
the United States was begun, together with a Thesaurus of American
formations. In addition to this the bibliographic work previously
described was initiated, so that the literature relating to American
geology should be readily accessible to the workers in the Survey. At this
point it became necessary to consider the best methods of apportioning the
work; that is, the best methods of dividing the geologic work into parts
to be assigned to the different corps of observers. A strictly geographic
apportionment was not deemed wise, from the fact that an unscientific
division of labor would result, and the same classes of problems would to
a large extent be relegated to the several corps operating in field and in
the laboratory. It was thought best to divide the work, as far as
possible, by subject-matter rather than by territorial areas; yet to some
extent the two methods of division will coincide. There are in the Survey
at present:
First, a division of glacial geology, and Prof. T.C. Chamberlin, formerly
State Geologist of Wisconsin is at its head, with a strong corps of
assistants. There is an important field for which definite provision has
not yet been made, namely, the study of the loess that constitutes the
bluff formations of the Mississippi River and its tributaries. But as this
loess proves to be intimately associated with the glacial formations of
the same region, it is probable that it will eventually be relegated to
the glacial division. Perhaps the division may eventually grow to such an
extent that its field of operations will include the whole Quaternary
geology.
Second, a division of volcanic geology is organized, and Capt. Clarence E.
Dutton, of the Ordnance Corps of the Army, is placed in charge, also with
a strong corps of assistants.
Third and fourth, two divisions have been organized to prosecute work on
the archæan rocks, embracing within their field not only all rocks of
archæan age, but all metamorphic crystalline schists, of whatever age they
may be found. The first division has for its chief Prof. Raphael Pumpelly,
assisted by a corps of geologists, and the field of his work is the
crystalline schists of the Appalachian region, or eastern portion of the
United States, extending from northern New England to Georgia. He will
also include in his studies certain paleozoic formations which are
immediately connected with the crystalline schists and involved in their
orographic structure.
The second division for the study of this class of rocks is in charge of
Prof. Roland D. Irving, with a corps of geologists, and his field of
operation is in the Lake Superior region. It is not proposed at present to
undertake the study of the crystalline schists of the Rocky Mountain
region.
Fifth, another division has been organized for the study of the areal,
structural, and historical geology of the Appalachian region, extending
from the Atlantic, westward, to the zone which separates the mountain
region from the great valley of the Mississippi. Mr. G.K. Gilbert has
charge of this work, and has a large corps of assistants.
Sixth, it seemed desirable, partly for scientific reasons and partly for
administrative reasons, that a thorough topographic and geologic survey
should be made of the Yellowstone Park, and Mr. Arnold Hague is in charge
of the work, with a corps of assistants. When it is completed, his field
will be expanded so as to include a large part of the Rocky Mountain
region, but the extent of the field is not yet determined.
It will thus be seen that the general geologic work relating to those
areas where the terranes are composed of fossiliferous formations is very
imperfectly and incompletely organized. The reason for this is twofold:
First, the work cannot be performed very successfully until the maps are
made; second, the Geological Survey is necessarily diverting much of its
force to the construction of maps, and cannot with present appropriations
expand the geologic corps so as to extend systematic work in the field
over the entire country.