EDITORIAL WORK OK GEOLOGIC MAPS. 99 
science of geology to that time. The method of publishing the Geo- 
logic Atlas of the United States was thoroughly revised. The engrav- 
ing division of the Survey having been established, it was possible, 
with the aid of the chief of that division, to prepare color patterns 
and tints, and the geologists in charge were enabled to exercise closer 
supervision of the engraving and printing of geologic maps. Thus 
greater accuracy of engraving and better register of the intricate 
colors were obtained. It was not until 1892, however, that any of the 
final maps of the atlas could be issued. 
To supervise the editing of this material and to devise and apply 
rules and regulations, a geologist was selected to act as editor of geo- 
logic maps, and from this beginning the section of geologic map 
editing has developed. 
These rules and plan of publication remained in force until December, 
1903, when the growth of the science demanded further changes, and 
new rules were formulated and put into effect in January, 1901. As 
the number and intricacy of the folios increased, the work of the sec- 
tion also increased and the force was enlarged. At present it consists 
of a geologist acting as editor, assisted by three draftsmen. 
The section of geologic maps has charge of the publication of the 
geologic folios. Its duties are to examine geologic maps and other 
illustrations to see that they are adequate for publication, and, if not, 
to properly prepare them; to read the proofs and compare them with 
the manuscripts; and to select the colors and patterns chosen for the 
representation of geologic formations. Errors and inaccuracies occur- 
ring in the manuscript or on the proof sheets are eliminated, and by 
careful study and selection the most effective and pleasing results of 
colors and patterns are obtained. The folios, which are portions of a 
great geologic atlas, are thus made uniform in style and form, whereas 
they would otherwise vary as widely as the temperaments of the 
various authors. 
A standard geologic folio comprises a descriptive text, in which the 
geography, topography, and geology of the area are described; a 
topographic map; a geologic map, printed in colors, showing the areal 
distribution of the geologic formations; a geologic map showing the 
deposits of economic value in stronger or more brilliant colors; a geo- 
logic map on which the underground structure of the rocks is exhibited 
by vertical sections representing what would be seen in deep trenches 
across the area; and a columnar section, in which the rocks are repre- 
sented in a vertical column in their normal relation one to another, 
accompanied by a condensed description of their composition, thick- 
ness, and relations. 
For special areas other maps or illustrations are included. Often 
it is desirable to present with the description a page of illustrations 
reproduced from photographs or sketches. For artesian- water areas 
