Plate 22, map of Rico Mountains. "dikes of Calico Peak porphyry." [Text heading is "porphyry of Calico Peak and vicinity."] Age is Tertiary.
Source: US geologic names lexicon (USGS Bull. 896, p. 318).
[Credits Whitman Cross, A.C. Spencer, and F.L. Ransome.] "Dikes of Calico Peak porphyry" occur on north slope and elsewhere in vicinity of Calico Peak [about 4 miles northwest of Rico] and in a sheetlike body in Dakota sandstone at head of Priest Gulch. Is a monzonite porphyry characterized by large orthoclase crystals. "Calico Peak porphyry alunitized" (a porphyry changed by solfataric action into a mass consisting chiefly of alunite) forms cone of Calico Peak. Age is Tertiary.
Source: US geologic names lexicon (USGS Bull. 896, p. 318).
[Calico Peak porphyry adopted by the USGS.]
Source: US geologic names lexicon (USGS Bull. 896, p. 318).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
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