. Bulletin of the Department of Geology. Geology. Vol. 4] Eeid.—The Comstock Lode. 185 secondary fissures at greater depths. The "west vein" and the "east vein" at the surface have been carefully described many times by previous observers,* and the fact that only the "east vein" carried values has caused much discussion. This "east vein" is merely the gash which reached the surface, thereby ap-. FiG. 2.—Ground plan of Comstock lode, showing disposition of faults. pearing as a vein occupying a fault plane and resultant fissure. These three gashes—the surf
. Bulletin of the Department of Geology. Geology. Vol. 4] Eeid.—The Comstock Lode. 185 secondary fissures at greater depths. The "west vein" and the "east vein" at the surface have been carefully described many times by previous observers,* and the fact that only the "east vein" carried values has caused much discussion. This "east vein" is merely the gash which reached the surface, thereby ap-. FiG. 2.—Ground plan of Comstock lode, showing disposition of faults. pearing as a vein occupying a fault plane and resultant fissure. These three gashes—the surface "east vein," the famous bo- nanza, and the "vein" now being worked, all have an identical origin. Their formation lies in the fact that the lower part of the hanging wall block has settled more than the upper, relative to the foot wall, and has been torn apart by the stresses developed. This form of ore deposit is rather new, and because of its evident importance deserves a distinctive recognition. The term "gash vein" is not suitable, obviously, and the name "rift vein" is sug- gested to cover the structure. Gold Hill.—The bonanzas of Gold Hill are found in the lode proper, near the east wall, and east of the low grade quartz. The * G. F. Becker, op. cit. Clarence King, '' Survey of Fortieth Parallel,'' Vol. III. John A. Church, "The Comstock Lode—Its Formation and History.''. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original University of California, Berkeley. Dept. of Geology. Berkeley : The University Press
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