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U.S. Geological Survey Central Publications Group

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New 1:24,000-scale geologic mapping along the Interstate-70urban corridor in western Colorado, in support of the State/USGS Cooperative Geologic Mapping Project, is contributing to amore complete understanding of the stratigraphy, structure,tectonic evolution, and hazard potential of this rapidlydeveloping region. The 1:24,000-scale Vail East quadranglestraddles the Gore fault system, the western structuralboundary of the Gore Range. The Gore fault system is acontractional structure that has been recurrently active sinceat least the early Paleozoic and marks the approximate easternboundary of the Central Colorado trough, a thick late Paleozoicdepocenter into which thousands of meters of clastic sedimentwere deposited...
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New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Frisco quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, K.S., 1999, Neogene basins of the northern Rio Grande rift�partitioning and asymmetry inherited from Laramide and older uplifts: Tectonophysics, v. 305, p. 141-152.), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene...
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The Sawmill Mountain quadrangle is located in the western Transverse Ranges of California, about 10 km west of Frazier Park. It includes Mt. Pinos, Mt. Abel (Cerro Noroeste), a part of the southern San Emigdio Mountains, and straddles an eleven-kilometer reach of the nearly east-west striking "Big Bend" section of the San Andreas Fault.South of the San Andreas Fault, the oldest rocks include undated amphibolite-grade biotite and hornblende-biotite gneiss that is probably early or middle Proterozoic in age. The older gneiss is intruded by strongly deformed and foliated biotite orthogneiss that has an age on biotite of 67.2+0.5 Ma (Late Cretaceous). Several other weakly foliated to massive Late Cretaceous granitic...
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Prime agricultural land along the Clear Creek floodplain, Colorado, attracted settlement in the 1850's but the demand for sand and gravel for 1900's construction initiated a sequence of events that exceeded previous interests and created the modified landscape and urban ecosystem that exists today. The Clear Creek valley corridor offers a landscape filled with a persistent visible and hidden reminder of it's past use.The map sheets illustrate the Clear Creek landscape as a series of compositions, both at the macro view (in the spatial context of urban structure and highways from aerial photographs) and micro view (from the civic scale where landscape features like trees, buildings, and sidewalks are included). The...
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The geology of the Salmon National Forest, Idaho, was compiled frompublished and unpublished sources and new field mapping by Evans, Lund,Tysdal, and Winkler between 1997 and 2001. The geology was compiledonto 1:100,000-scale topographic base maps for input into a geographicinformation system (GIS). The digital geologic map database can bequeried in many ways to produce a variety of geologic maps.
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