. 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. resembles BearButte, ma^ be sul»rdinate to a large subterranean mass of whichmerely the crest is revealed at Citadel Rock. Crow Peak is the highest point in the northern Hills Ijing so nearto the Red Valley. Its proximity to the plains gives to its reliefexcessive prominence. SecMi from the east (PI. XXIX) the conspicu-ous elements of its prolilc are a sharp conical southern peak of por-phyry and a steep monoclinal scarp of limestone re
. 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. resembles BearButte, ma^ be sul»rdinate to a large subterranean mass of whichmerely the crest is revealed at Citadel Rock. Crow Peak is the highest point in the northern Hills Ijing so nearto the Red Valley. Its proximity to the plains gives to its reliefexcessive prominence. SecMi from the east (PI. XXIX) the conspicu-ous elements of its prolilc are a sharp conical southern peak of por-phyry and a steep monoclinal scarp of limestone resting against it onthe north side. Thrust up through the limestone where the sedimentshad long, gentle dip slopes northward, the igneous core is completely. Fig. !)3.—South .slopi-of Crow Peak, showing change of dip. revetted with rounded imbricating monoclinal ridges of Silurian andCarboniferous limestone dipping steeply away on all sides (Pis. XIXand XLI). Wherever the contact was examined closel}^ Cambrianbeds were found, and on the north side peripheral sills in Cambrianoccupy the hollows in the ])end, as figured in the original (Henr} jMoun-tains) laccoliths. Dips taken while ascending a gulch on the northside of the mountain varied from horizontal one-half mile north of themountain to 27°, 40^, 65°, and 89° in Minnelusa, gray limestone, andCambrian beds. A tunnel at the head of the gulch, cut horizontall}^ for110 feet southwest into the mountain, passes through 105 feet of por-phyry and penetrates for 5 feet at the end a bed of quartzitic sandstonedipping 12°, N. 20° W. The contact of the porphyry with this sand-stone is ragged and trends NNW. The sandstone shows Oholus andevidently represents the lowest of the Cambrian beds.
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Keywords: ., bookauthorunitedst, bookcentury1900, bookdecade1900, bookyear1901
