302 ' REVIEWS 
The Copper Deposits of the Robinson Mining District, Nevada. By 
ANDREW C. Lawson. (University of California Publications, 
Bulletin of the Department of Geology, Vol. IV, No. 14 [May, 
1906] pp. 287-357.) 
Many thousands of feet of Cambrian to Carboniferous rocks are exposed 
in this region. They lie in open folds, and in them are igneous intrusions 
of post-Carboniferous, probably mid-mesozoic age, and also later intrusions, 
probably Tertiary. These latest intrusions are of a light-colored, acid, 
porphyritic rock, and the ore bodies occur usually in them. The ore is 
low grade, but extensive. 
The earlier intrusives are of especial interest in that, while they are post- 
Carboniferous, the author considers them of the same age as numerous 
other similar batholiths of the Basin Ranges usually considered archean. 
E. W. S$. 
Water Powers of Northern Wisconsin. By LEONARD S. SMITH. 
(Water Supply and Irrigation Paper No. 114, U. S. Geological 
Survey, 1906.) Pp. 145; 5 plates, 5 figures. 
Water power is an especially important subject in Wisconsin, because 
that state is so distant from coal-supply. Mr. Smith points out that the 
available unused water power is considerable, and makes estimates as to 
its exact amount. The physical geography and drainage are discussed. A 
wide highland, 1,000-2,000 feet above the sea, crosses the northern part 
of the state, from which the drainage goes out in all directions. 
E. W. 98. 
