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The Leadville North 7.5' quadrangle lies at the northern end of the Upper Arkansas Valley, where the Continental Divide at Tennessee Pass creates a low drainage divide between the Colorado and Arkansas River watersheds. In the eastern half of the quadrangle, the Paleozoic sedimentary section dips generally 20–30 degrees east. At Tennessee Pass and Missouri Hill, the core of the Sawatch anticlinorium is mapped as displaying a tight hanging-wall syncline and foot-wall anticline within the basement-cored structure. High-angle, west-dipping, Neogene normal faults cut the eastern margin of the broad, Sawatch anticlinorium. Minor displacements along high-angle, east- and west-dipping Laramide reverse faults occurred in...
Tags: 10Be, 26Al, Belden Formation, Buckeye Peak, Bull Lake glaciation, Camp Hale, All tags...
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The Homestake Reservoir 7.5' quadrangle lies at the northwestern end of the Upper Arkansas Valley, and headwaters of the Arkansas River, and the Roaring Fork, Fryingpan, and Eagle Rivers of the Colorado River system. The quadrangle lies within tectonic provinces of the 1.4 Ga Picuris Orogeny, the late Paleozoic Ancestral Rockies, Late Cretaceous-Paleocene Laramide orogeny, Oligocene to Miocene, and Pliocene?, volcanism, and Miocene to the present Rio Grande rift extensional tectonics. In the eastern half of the quadrangle, high-angle, east-dipping, Neogene normal faults displace Proterozoic rocks, and locally Mio-Pliocene? volcanic rocks. Many quartz veins and hydrothermally altered zones are exposed along the eastern...
Categories: Data; Types: Downloadable, GeoTIFF, Map Service, Raster; Tags: 10Be, 26Al, 10th Mountain Division Hut, Bald Eagle Mountain, Bear Lake, Brady Lake, All tags...
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New 1:24,000-scale geologic mapping in the Colorado National Monument Quadrangle and adjacent areas, in support of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of and data for the stratigraphy, structure, geologic hazards in the area from the Colorado River in Grand Valley onto the Uncompahgre Plateau. The plateau drops abruptly along northwest-trending structures toward the northeast 800 m to the Redlands area and the Colorado River in Grand Valley.In addition to common alluvial and colluvial deposits, surficial deposits include Holocene and late Pleistocene charcoal-bearing valley-fill deposits, late to middle Pleistocene river-gravel terrace deposits,...
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Numerous 40Ar/39Ar experiments on sanidine and biotite from 22 ash beds and 3 volcaniclastic sand beds from the Greater Green River, Piceance Creek, and Uinta Basins of Wyoming, Colorado, and Utah constrain ~8 m.y. of the Eocene Epoch. Multiple analyses were conducted per sample using laser fusion and incremental heating techniques to differentiate inheritance, 40Ar loss, and 39Ar recoil. When considered in conjunction with existing radioisotopic ages and lithostratigraphy, biostratigraphy, and magnetostratigraphy, these new age determinations facilitate temporal correlation of linked Eocene lake basins in the Laramide Rocky Mountain region at a significantly increased level of precision. To compare our results...
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The Ennis 1:100,000 quadrangle lies within both the Laramide (LateCretaceous to early Tertiary) foreland province of southwesternMontana and the northeastern margin of the middle to late TertiaryBasin and Range province.The oldest rocks in the quadrangle are Archean high-grade gneiss, andgranitic to ultramafic intrusive rocks that are as old as about 3.0Ga. The gneiss includes a supracrustal assemblage of quartz-feldspargneiss, amphibolite, quartzite, and biotite schist and gneiss. Thebasement rocks are overlain by a platform sequence of sedimentaryrocks as old as Cambrian Flathead Quartzite and as young as UpperCretaceous Livingston Group sandstones, shales, and volcanic rocks.The Archean crystalline rocks crop...


    map background search result map search result map Synoptic reconstruction of a major ancient lake system: Eocene Green River Formation, western United States Geologic map of the Ennis 30' X 60' quadrangle, Madison andGallatin Counties, Montana, and Park County, Wyoming Geologic Map of Colorado National Monument and Adjacent Areas, Mesa County, Colorado Data release for Geologic Map of the Leadville North 7.5' quadrangle, Eagle and Lake Counties, Colorado Data release for Geologic Map of the Homestake Reservoir 7.5' quadrangle, Lake, Pitkin, and Eagle Counties, Colorado Data release for Geologic Map of the Leadville North 7.5' quadrangle, Eagle and Lake Counties, Colorado Data release for Geologic Map of the Homestake Reservoir 7.5' quadrangle, Lake, Pitkin, and Eagle Counties, Colorado Geologic Map of Colorado National Monument and Adjacent Areas, Mesa County, Colorado Geologic map of the Ennis 30' X 60' quadrangle, Madison andGallatin Counties, Montana, and Park County, Wyoming Synoptic reconstruction of a major ancient lake system: Eocene Green River Formation, western United States