Filters: Tags: Sawatch Range (X)
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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...
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,
This release presents the GIS data (in GDB, shapefile, and e00 [coverage] formats) and metadata for a 1:24,000-scale geologic map of the Poncha Pass area in central Colorado. A cartographic version of the geologic map, including map unit descriptions, interpretative text, and accessory figures and tables, is being separately published as a U.S. Geological Survey Scientific Investigations Map (SIM). The map area is irregular in shape, covering all of one 7.5' quadrangle (Poncha Pass) and parts of five others (Mount Ouray, Maysville, Salida West, Salida East, and Wellsville). The map boundaries were drawn to cover all of the "Poncha mountain block", coincident with the approximately 15-kilometer-long northwestern...
This report summarizes the geochronologic results from boulders deposited on glacial moraines in the southern Sawatch and Sangre de Cristo Mountains of south-central Colorado. Within this report are detailed the methodology used to collect samples of whole rock, determine the concentrations of cosmogenic beryllium 10 in purified quartz isolated from those samples, and use those nuclide concentrations to calculate surface exposure ages. This report should be used as supplementary material for any publication(s) that uses the nuclide concentrations and/or ages reported herein. This version supersedes all previous age estimates and reports.
This 1:50,000-scale geologic map represents a compilation of the most recent geologic studies of the upper Arkansas River valley, between Leadville and Salida, Colorado. The valley is structurally controlled by an extensional fault system that forms part of the prominent northern Rio Grande rift, an intra-continental region of crustal extension. This work also incorporates new detailed geologic mapping of poorly understood areas within the map area and reinterprets previously studied areas, aided by lidar data that covers 59 percent of the map area. The mapped region extends into the Proterozoic metamorphic and intrusive rocks in the Sawatch Range west of the valley and the Mosquito Range to the east. Paleozoic...
Categories: Data;
Tags: 207Pb/206Pb zircon age,
40Ar/39Ar age,
Arkansas River,
Balltown,
Balltown placer gold mining areas,
Ice surface topography of a late Pleistocene glacier complex, herein named the Taylor River Glacier Complex (TRGC), was reconstructed on the basis of detailed mapping of glacial landforms combined with analyses of aerial photos and topographic maps. During the last glacial maximum (LGM), the TRGC covered an area of 215 km2 and consisted of five valley or outlet glaciers that were nourished by accumulation in cirques basins and/or upland ice fields. Equilibrium-line altitudes (ELAs) for the glaciers of the TRGC were estimated using the accumulation-area ratio method, assuming that ratio to be 0.65���0.05. ELAs thus derived ranged from about 3275 to 3400 m, with a mean of 3340���60 m. A degree-day model (DDM) was...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Geomorphology,
colorado,
equilibrium-line altitudes,
glaciation,
pleistocene climate,
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