Review of Recent Geological Literature. 113 
Sorurna, Italy, Auvergne, France, and from New Zealand, 
These are lenticular generally, but some are much elongated. 
n. h. w. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
Twelfth Annual He/port of the United States Geological Survey to tJu Sec- 
retary of the Interim-, 1890-91. By J. W. Powell, Director. Pari I. 
Geology; pp. xiii 675, with 53 plates, and 81 figures in the text. Pari II. 
Irrigation; pp. xviii, 576, with plates 54-146, and figures 81-270 in the 
text. Washington, 1891. 
These valuable large volumes reportiug the progress of our national 
survey during'the fiscal year ending June 30, 1891, were distributed to 
colleges and universities, public libraries, and the working geologists of 
the country, nearly three years alter that date, although bearing the 
imprint of 1891. In the first volume the director's annual report and 
the administrative reports of the chiefs of divisions of the survey form 
'210 pages. These are accompanied by four geological papers, as re- 
viewed in the following- pages, forming the remainder of this volume. 
The second, devoted to the surveys and plans for the improvement of 
the arid lands of the western half of the United Stales by irrigation, 
contains three reports: first, upon the location and survev of reservoir 
sites, by A. H. Thompson, comprising 212 pages, with four plates and 
142 figures: second. Hydrography of the arid regions. In P. II. NEWELL, 
149 pages, with 4!) plates and seven figures: and third, Irrigation in 
India, by HERBERT M. Wilson. It)!) pages, with 40 plates and 41 figures. 
In topographic, geologic, paleontologic, chemical and physical work. 
compilation of statistics of mineral products, the departments of en- 
graving and printing, the library, and disbursements, thirty-two sum- 
mary reports of the progress of the survey are presented. 
Up to date of June 30, 1891, the number of topographic sheets of the 
United Slates atlas which had been engraved was 173, comprising about 
181,000 square miles. These sheets are on three different scales, accord- 
ing to i he character of the country, I he proportion of population, and 
the importance of geologic features to be noted. Thus. 177 sheets have i he 
scale of 1:62,500, or about one mile loan inch, usually with contour in- 
tervals of 20 feet, i hese being mosi Ij in t he New England and At lain ic 
stales south to the Potomac river; 237 sheets are on the scale of 1:125,- 
000, or about two miles to an inch, usually with Contours for each 50 or 
100 feet; and 59 sheets, mostly in the mountainous or deserl < lordilleran 
belt, are on the scale of 1:250,000, or about four miles to an inch, with 
contours for each 200 or 250 feet. The areas of the si is for i hese se> 
era! scales are bounded respectively hs arcs of J. \. and 1 degree in lati- 
tude and longil ude. 
