. Annual Reports of the Department of the Interior for the Fiscal Year Ended June 30, 1900--Twenty-First Annual Report of the United States Geological Society. tion of La Plata Mountains (Flolraes). ottered an easier passage for spreading horizontally than was possil)leby continuing upward. Upward movement, or doming, eventually. ling of Two Bit sills, a. Southeast sido of Twest sidp of Two Bit Canyon. took place, when with continued inflow the mass and viscosity of the por-phyry, us the result of lateral spread and cooling, were sufficient to flex TWO BIT REOION. 207 the thick limestones. In
. Annual Reports of the Department of the Interior for the Fiscal Year Ended June 30, 1900--Twenty-First Annual Report of the United States Geological Society. tion of La Plata Mountains (Flolraes). ottered an easier passage for spreading horizontally than was possil)leby continuing upward. Upward movement, or doming, eventually. ling of Two Bit sills, a. Southeast sido of Twest sidp of Two Bit Canyon. took place, when with continued inflow the mass and viscosity of the por-phyry, us the result of lateral spread and cooling, were sufficient to flex TWO BIT REOION. 207 the thick limestones. In the tigure the diorite-porphyi}- at the rightis probably made up of a number of sills, though porphyrytalus covers the whole hill slope, and if Cambrian beds occur U] there they are completely masked by the slide rock. Inthe uppermost bed, r/, theie are at least 250 feet of diorite-porphyry exposed, and apparently this mass lifted the sye-nite-porphyry above. That the upper laccolith ends ratherabruptly to the northwest (PI. XX) is proved by the factthat the walls of Two Bit Canyon opposite to the slopefigured in the section (fig. 74) show none of the upper por-phyry, and only one diorite-porphyry bench conforming tothe bench in the figure. At the contact 7j the Silurian lime-stone is highly mineralized and silicified. At
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