122 The American Geologist. February, 1904. 
physicists and astronomers. The vigor and perspicacity with 
which it is presented by its author render its acceptance more 
easy and probable. It is at least destined to take rank among 
the leading hypotheses of the cause of the ice age, and it must 
be reckoned with by all who attempt the solution of that stand- 
ing geological problem. ' x. h. w. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
The Geology of Worcester, Massaclnisctts. By Joseph H. Perry and 
B. K. Emerson. Published by the Worcester Natural History So- 
ciety. Worcester, 1903. 2 maps. 40 plates. 166 pages. 
■'This book has not been written for geologists. It has been written 
for the people of Worcester; for those who have no technical knowl- 
edge of the subject of geology, and in such a style, we hope, that, taken 
in hand, it will serve as a guide over the fields and through the streets 
in the study of the rocks of Worcester and of their relations to one 
another. But while the book is written, for the amateur in nature study, 
rather than for the professional geologist, we have not tried to slide 
over, or omit the problems here presented, but to solve them in untech- 
nical language. To the people of Worcester, then, we dedicate this 
book, hoping that it may b a source of pleasure and profit in their walks 
about the city." 
The foregoing, from the author's preface, is too modest. The book 
is worthy of being read by any geologist. Worcester presents a great 
variety of geological structure and of geological and mineralogical 
problems. The simple manner of treatment does not detract from 
the completeness of the geological descriptions : and the excellent plates 
add very greatly to the vividness of the story. The region is Carbon- 
iferous, pierced by granite and other intrusives. producing a variety 
of schists and gneisses. n. h. w. 
Descriptive geology of N'evada soitfli of the fortieth parallel and adjacent 
portions of California.. By Josi.\h Edw.\rd Spurr. U. S. Geol. 
Survey, Bull. 208, 222 pp., 8 pis.. 1903. 
In 1899 Mr. Spurr visited Nevada and crossed the state several 
times from east to west, the primary object of the work being to obtain 
data for a general geologic map of the region. His routes were planned 
to cover as far as possible territory not yet crossed by lines of geolog- 
ical reconnaissance, so that the information obtained could be added 
to that already at hand. The result is a general geologic map, which ac- 
companies this report, of Nevada south of the fortieth parallel and of 
a considerable portion of adjacent parts of California. In addition to 
