Joseph LeConte—Genesis of Metalliferous Veins. 5 
Such, we believe, is an outline of a true theory of the genesis 
of metalliferous veins, a theory apparently confirmed by the 
study of causes now in operation at Sulphur Bank and Steam- 
boat Springs, and probably many other places in California and 
Nevada.* e are now prepared to still further confirm the 
theory by applying it to the explanation of all the phenomena 
of veins. But before doing so it is necessary that some grave 
objections recently raised should be removed. 
Recently 
phur Bank. According to him, moving water will not deposit, 
for in order that deposit should take place the water must be 
Process still going on, or investigate directly the causes still in 
Operation. In brief his view seems to be, that the closed cavi- 
ties of great fissures, like the closed fossil-cavities of stratified 
rocks and the closed vapor-cavities of eruptives are filled by 
leachings from the immediate bounding wall-rocks of the fis- 
Sures. The process is a sort of aggregation of soluble matters 
* Feeble solfataric action is still going on and probably still depositing metallic 
Sulphides in Comstock Lode. (Becke cy = : 
Untersuchungen iiber Erzginge.” FF. Sandberger, Wiesbaden, 1882. I 
ve hot seen the full work, but only a thorough resumé of the part on genesis of 
veins by G. Maillard in the Archives des Sciences for Dec., 1882, vol. viii, p. 320. 
