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Robert E. Powell

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The Valley Mountain 15’ quadrangle straddles the Pinto Mountain Fault, which bounds the eastern Transverse Ranges in the south against the Mojave Desert province in the north. The Pinto Mountains, part of the eastern Transverse Ranges in the south part of the quadrangle expose a series of Paleoproterozoic gneisses and granite and the Proterozoic quartzite of Pinto Mountain. Early Triassic quartz monzonite intruded the gneisses and was ductiley deformed prior to voluminous Jurassic intrusion of diorite, granodiorite, quartz monzonite, and granite plutons. The Jurassic rocks include part of the Bullion Mountains Intrusive Suite, which crops out prominently at Valley Mountain and in the Bullion Mountains, as well as...
Categories: Publication; Types: Citation; Tags: Geologic Quadrangle
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Geological, geochemical, and geophysical evidence, together with a 'review of historical mining and prospecting activities, suggests that most of the Whitewater Wilderness Study Area has low potential for all types of mineral and energy resources- including precious and base metals, building stone and aggregate, fossil fuels, radioactive-mineral resources, and geothermal resources. One small area in the southern part of the study area shows evidence of gold and silver mineralization, and this locality has a low to moderate potential for the discovery of low-grade gold and silver resources.
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This data set maps and describes the geology of the San Bernardino Wash 7.5 minutequadrangle, Riverside County, southern California. The quadrangle, situated inJoshua Tree National Park in the eastern Transverse Ranges physiographic andstructural province, encompasses parts of the northwestern Eagle Mountains,east-central Pinto Basin, and eastern Pinto Mountains.The quadrangle is underlain by a basement terrane comprising metamorphosedProterozoic strata, Mesozoic plutonic rocks, and Jurassic and Mesozoic and (or)Cenozoic hypabyssal dikes. The basement terrane is capped by a widespread Tertiaryerosion surface preserved in remnants in the Pinto and Eagle Mountains and buriedbeneath Cenozoic deposits in Pinto Basin....
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This data set maps and describes the geology of the Porcupine Wash 7.5 minute quadrangle, Riverside County, southern California. The quadrangle, situated in Joshua Tree National Park in the eastern Transverse Ranges physiographic and structural province, encompasses parts of the Hexie Mountains, Cottonwood Mountains, northern Eagle Mountains, and south flank of Pinto Basin. It is underlain by a basement terrane comprising Proterozoic metamorphic rocks, Mesozoic plutonic rocks, and Mesozoic and Mesozoic or Cenozoic hypabyssal dikes. The basement terrane is capped by a widespread Tertiary erosion surface preserved in remnants in the Eagle and Cottonwood Mountains and buried beneath Cenozoic deposits in Pinto Basin....
Categories: Publication; Types: Citation; Tags: Open-File Report
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Geological, geochemical, and geophysical evidence, together with a review of historical mining and prospecting activities, suggests that most of the Bighorn Mountains Wilderness Study Area has low potential for the discovery of all types of mineral and energy resources-including precious and base metals, building stone and aggregate, fossil fuels, radioactive-mineral resources, and geothermal resources. Low-grade mineralization has been documented in one small area near Rattlesnake Canyon, and this area has low to moderate potential for future small-scale exploration and development of precious and base metals. Thorium and uranium enrichment have been documented in two small areas in the eastern part of the wilderness...
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