Iteoiew of Recent Geological Literature. 177 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
Geologic Atlas of the United States. By the U. S. Geological Survey: 
J. W. Powell, Director; Bailey Willis, Editor of geologic maps: S. 
J. Kubel, Chief engraver. (Washington, D. C, 1894 and 1895.) The 
first twenty parts, called folios, of the elaborate atlas which is designed 
to include maps and descriptions of our entire national domain, have 
been issued. In the "library edition" for general distribution and sale 
(at 25 cents each), the descriptive text of folio 1 is dated January, 1893, 
and its map sheets July. 1893, but the title page bears the date 1894. In 
folio 20 the dates are, for the text, April, 1895: and for the map sheets, 
July, 1895. 
Seventeen of these folios cover, for each, an area bounded by a half 
degree of latitude and longitude on each side, and are on the scale of 1: 
125,000, or slightly less than two miles to an inch, which is to be the 
scale for nearly all the atlas. The Livingston folio, in Montana, and 
the Lassen Peak folio, in California, are enclosed by sides measuring 
one degree, and are on the scale of 1:250,000: and the Anthracite-Crested 
Butte folio, in Colorado, comprises maps of two adjoining areas, each a 
quarter of a degree long and wide, on the scale of 1:62,500, or almost a 
mile to an inch. 
The Pike's Peak folio, between 38° 30' and 39° latitude, and between 
105° and 105° 30' longitude, has a length of 31.5 miles and a width of 27 
miles, approximately, thus including 931.5 square miles. As the entire 
area of the United States (without Alaska) is about 3,025,000 square 
miles, it would require 3,250 folios, if all were on this uniform scale, 
with no allowance for the fractional folios on the boundaries, by which 
the {lumber must be considerably increased. At an average rate of pub- 
lication of thirty-five folios yearly, therefore, the atlas will require a 
hundred years for its completion. The beginning of this vast work is 
most admirably performed. The practical usefulness of these maps and 
descriptions, and their great value in advancing science, will undoubt 
edly secure, as they certainly deserve, the continued and generous sup- 
port of Congress through the long time, whether fifty years or a century 
or more, which will be needed for thoroughly accurate and detailed to- 
pographic and geologic mapping of all the country. 
In size the folios measure about 18 by 22 inches, and the map sheets 
nearly 11 by 18 inches, outside of which, on the margins, are the titles, 
legend, scale, etc. On the inside pages of the stiff paper covers of each 
folio, Director Powell gives an excellent explanation of the contour lines 
and other topographic delineations, and of the principles of geology, so 
fully as to enable any intelligent person to study the maps and sections 
understanding^', and to learn from them the form and relative altitudes 
of the land surface and the areal and structural relations of the rock 
formations. 
Each folio has several pages of description, introduced by a general 
statement of the grand topographic and geologic features of the region 
