REVIEWS QI 
sandstones and shales rich in alumina, which was probably in the form 
of bauxite. 
Methods of prospecting, mining, and milling are described in chapter 
xi. It is prefaced by a historical sketch of corundum in the East and an 
account of discoveries and mining in the United States and Canada. 
Chapter xii deals with the various other economic minerals of the 
peridotite belt—chromite, asbestos, genthite, serpentine, and limonite. 
Chromite in promising quantities has been found at a number of localities 
in North Carolina, particularly in Yancey and Jackson Counties. Asbestos 
(chrysotile) of good quality frequently occurs, but no mining has yet devel- 
oped in North Carolina. The well-known Canadian deposits, however, 
are in the northward extension of this belt. The nickel ores (genthite and 
related silicates) occur widely, and are unquestionably derived from the 
decomposing peridotites, in the joints of which they are found. Serpen- 
tine in large bodies is a direct alteration product of the peridotites in North 
Carolina, but its occurrence is extremely limited, as compared with the 
abundance of the latter. Residual limonite beds have sometimes been 
formed from decomposing peridotites, and these have been utilized as 
iron ores in some portions of the belt in New York and Pennsylvania. 
An appendix of twenty pages consists of a bibliography of American 
peridotites, corundum, and associated minerals. Copious references to both 
American and foreign literature are also given in footnotes throughout the 
report. 
J. VoLNEY LEWIS 
RUTGERS COLLEGE 
New Brunswick, N. J. 
Lower Paleozoic Formations in New Mexico. By C. H. GORDON 
and L. C. Graton. (American Journal of Science, Vol. XXI, 
PP- 390-95, 1906.) 
In Science for April 13, 1906, announcement was made of the discovery 
in Sierra and Grant counties, New Mexico, of formations belonging to 
the Cambrian, Ordovician, Silurian, and Devonian series. A more 
extended account of these formations by C. H. Gordon and L. C. Graton 
of the U. S. Geological Survey appeared in the American Journal oj 
Science for May, 1906. A full account of the investigations upon which 
these announcements are based will appear in a forthcoming report of 
the U. S. Geological Survey, on the mining districts of New Mexico. 
The Cambrian rocks consist of quartzites, sandstones, and shales, 
with occasional beds of limestone. They range in thickness from 50 
