264 The American Geologist. October, 1893 
feet thick which lies near Berkeley, Cal., and is of late Cretaceous or 
early Tertiary age. It presents three appearances which are described, 
the porphyritic, spherulitic and glassy facies. Analyses of all are given, 
which, though showing differences in composition, yet justify the single 
term applied to the whole intrusion. 
Geology of the Eureka District, Nevada, with an atlas. Arnold 
Hague. U. S. Geol. Sur. Moncgraph, xx, Washington, pp. 394, quarto; 
six petrographic plates. 
This is another of those standard publications which have rapidly 
brought the United States Geological Survey to the front amongst the 
geological organizations of the world. It is a work which has been 
prosecuted with that otium cum dignitate which should characterize 
an investigation which had to fear no cessation from lack of time or 
resources. Begun in the administration of Clarence King, in 1880, it 
has continued, with various interruptions, to the rendering of the re- 
port, June 20, 1891, covering a period of eleven years. Mr. Hague was 
assisted by Mr. C. D. Walcott and Mr. J. P. Iddings. The former re- 
ported the "Paleontology of the Eureka District,*' in 1884, and it was 
published as Monograph viii of the U. S. Geol. Survey. Mr. Iddings' 
report on the volcanic rocks of the district, though now nearly nine 
years old, is a thorough discussion of those petrographic structures and 
mineral characters which till then had been but little studied in Amer- 
ica. Mr. Hague's contribution, which constitutes the bulk of the text 
of the volume, is strictly a geological report, presenting in one sys- 
tematical review the results of the separate special researches, with 
the field observations, and deducing such general statements as the 
facts warrant. The atlas consists of thirteen sheets, the topographical 
portion of which was under the direction of Mr. F. A. Clark. The 
geological coloring and the structural sections are by the various field- 
observers. The atlas is dated 1883, but was not issued until final cor- 
rection and the completion of the text. Some of the summary results 
of this volume appeared in the "Third Report of the Director," in 1882, 
accompanied by a geological map similar to sheet iv of the atlas. 
A convenient "outline of this volume" prepared by the author pre- 
cedes the text, and from this the following summary is condensed: 
The area reported on is about 20 miles square, embracing mountains 
that reach the altitude of 9,000 to 10,500, presenting a rough aspect, 
and rising about 3,000 feet above the adjoining valleys. Paleozoic 
sedimentary rocks constitute the mountains and the valleys, the latter, 
however, being more or less covered with Quaternary detritus from 
the mountains. These indurated rocks embrace but one unconformity 
from base to summit, so far as recognized, and took their place as a 
part of a broad continental land mass after the deposition of the upper 
Coal Measures limestone. Their thickness is 30,000 feet, with Cam- 
brian, Silurian, Devonian and Carboniferous all represented by charac- 
teristic fauna 1 . Various folding and faulting have broken up these 
strata into great blocks, which constitute the principal mountains. 
