The deposits of the useful minerals & rocks; their origin, form, and content . 200 <*oo 600 eoo 1000 feet Cambrian Silur. Devon. Carbon. 111. Con- II. Con- 1 Con- White Grey Lower White Parting- Blue tact tact. tact Porphyry Porpdyry Quarzite Lime- Quarzite Leadville- stone Limestone Ore bodies Fig. 352.—Geological map of a portion of the Leadville district, .showing the the different formations and ore-bodies. Emmons and Irving, Washington, THE METASOMATIC LEAD-SILVER-ZINC DEPOSITS 763 is situated the eruptive rocks preponderate, and the contour of the districtis cond
The deposits of the useful minerals & rocks; their origin, form, and content . 200 <*oo 600 eoo 1000 feet Cambrian Silur. Devon. Carbon. 111. Con- II. Con- 1 Con- White Grey Lower White Parting- Blue tact tact. tact Porphyry Porpdyry Quarzite Lime- Quarzite Leadville- stone Limestone Ore bodies Fig. 352.—Geological map of a portion of the Leadville district, .showing the the different formations and ore-bodies. Emmons and Irving, Washington, THE METASOMATIC LEAD-SILVER-ZINC DEPOSITS 763 is situated the eruptive rocks preponderate, and the contour of the districtis conditioned rather by faulting than by folding, while the landscapepresents itself as an accidented rather than an undulating country. Thus,a number of steps bounded by faults are formed, the most prominent ofthese on the surface being known as Breece Hill, Iron Hill, Carbonate Hill,and Fryer Hill, respectively. Among the sediments participating in thisgeological complex the more important are, the Lower quartzite, which isprobably Cambrian ; the White limestone of the Silurian ; the Partingquartzite of the Devonian ; and the extremely important blue Leadvillelimestone, which is of Carboniferous age. Among the eruptive rocks, thoseknown locally as the Grey and White porphyries are the most grey variety is a monzonite- and quartz-monzonite porphyry, whilethe white is regarded as a rhyoUte-porphyry. From Fig. 352 it is seenthat the latter occupies la
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
