REVIEWS 855 
is an interesting discussion on the concentration of dyscrasite and 
antimonial silver chloride where the lode is cut by cross veins or 
“indicators.” The author finds it necessary to invoke the aid of the 
electro-magnetic currents of the earth’s crust acting along the cross 
veins to account for this particular form of deposition. 
Copper Ores in the Permian of Texas. By E. J. SCHMITZ, JR., pp. 
97-108 (discussion p. 1051). The copper ores of the Texas Permian 
occur as pseudomorphs of wood or as nodules or copper-bearing shale, 
slate or clay, and was deposited under much the same conditions as the 
“« Hupperschiefer” in the German Permian, the chief difference being 
that the American ore is in the main a carbonate or silicate, while the 
German is a sulphide. 
Vein Walls. By T. A. RICKARD, pp. 193-241 (discussion p. 
1153). A valuable dissertation upon the relation of ore deposition 
to the composition and structure of the inclosing strata. 
Sketch of a Portion of the Gunnison Gold Belt, Including the Vulcan 
and Mammoth Chimney Mines. By ARTHUR LAKES, pp 440-448. 
Gold in Granite and Plutonic Rocks. By Wi LLiAM P. BLAKE, pp. 
290-298. A summary of a number instances of the occurrence of 
gold as a primary constituent of granite and plutonic rocks. 
Faulting and Accompanying Features Observed in Glacial Gravel and 
Sand in Southern Michigan. By Cart HENRICH, pp. 460-464 (discus- 
sion p. 1102). The faulting occurs in stratified gravel. The fault planes 
are from seven to twelve feet apart, and none have a throw of less than 
seven inches. Along these fault planes nodules have been formed 
by ascending currents of water. The explanation offered is that lateral 
pressure was caused by two glaciers converging along Silver Creek and 
Goose Greek valleys. 
Further Notes on the Alabama and Georgia Gold-Fields. By 
WILLIAM H. BREWER, pp. 464-472. 
The Ore-Shoots of Cripple Creek, Colorado. By EDWARD SKEWES, 
pp. 553-579. A detailed description of the ore-shoots of a portion of the 
Cripple Creek district, and their relations to the vein fissures. 
Traces of Organic Remains from the Hurontan (2) Sertes at the Tron 
Mountain, Michigan, etc. By W. S. GREESLEY, pp. 527-534. An 
account of the author’s discovery of certain markings on the iron ore 
