212 The American Geologist. March, 1897 
Pages 543-570, with figures 70-100, by T. Nelson Dale, describe 
"Structural Details in the Green Mountain Region and in eastern New 
York.'" The author shows, by the excellent illustrations, how the indi- 
vidual ledges, and even hand specimens, in an area of mountain crump- 
ling often display results of folding, cleavage, and brecciation, which 
are traceable to the motions of the rock particles participating in the 
disturbances of the great mountain masses. 
In pages 571-874, with plates cvtii-cxvii and figures 101-1G9, a very 
thorough study is presented by Prof. Charles R. Van Hise, under the 
title, "Principles of North American Pre-Cambrian Geology," with an 
appendix, by Leandeb Miller Hoskins, on "Flow and Fracture of 
Rocks as related to Structure." Folds, cleavage and fissility, joints, 
faults, and the varied phases of metamorphism, are carefully and in- 
structively considered: after which the historical geology of the Ar- 
chean and Algonkian districts of the United States and Canada is re- 
viewed, attention being especially directed to illustrations of the princi- 
ples earlier stated. 
The concluding paper of volume I, by Henky Gannett, chief topog- 
rapher, gives a "Summary of the Primary Triangulation executed by 
the United States Geological Survey between the years 1882 and 1894." 
About a sixth part of our national domain, excluding Alaska, has been 
covered by this triangulation. 
Volume II. — The first paper of volume ii is by Whitman Cross and 
R. A. F. Penrose, Jr., on the "Geology and Mining Resources of the 
Cripple Creek District, Colorado," comprising pages 1-209, with 14 
plates and 37 figures. The gold production of this district during the 
first three years of its development, 1892 to 1894, is estimated as about 
$7,000,000; and the value of the ores shipped from the mines, contain- 
ing free gold and telluride of gold, varies from $20 to several thousand 
dollars per ton. The veins occur at fault planes of slight displacement 
in and near the area of eruptive rocks which overlie and partly surround 
a volcanic vent and which are themselves surrounded by granite. It is 
believed that the gold and associated vein minerals were derived by 
solution from the volcanic rocks, and, to a less extent, from the fidja- 
cent granite. 
Pages 211-276. with plates xv-xvii and figures 38-41, are entitled "A 
Geological Reconnaissance across Idaho," by George H. Elurebge. 
The belt examined extends from southwest to northeast by Boise and 
Salmon City. The rocks are referred to the Archean, Algonkian, and 
Paleozoic eras, with Tertiary sandstones and clays, abundant Quater- 
nary gravels, and eruptives which are regarded as possibly of all ages 
from Archean to Recent. 
Prof. N. S. Shaler, in pages 277-341, with plates xviii-xxiv, treats of 
"The Geology of the Road-building Stones of Massachusetts, with 
some Consideration of Similar Materials from other parts of the United 
States." Laboratory tests of road materials, which have been performed 
at Harvard University for the highway commission of Massachusetts, 
are described, with detailed statement of their results, and with notes 
