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This map illustrates extents and types of unconsolidated deposits and bedrock in the Big Delta A-4 Quadrangle, Alaska. This map is based on field observations begun by P�w� in 1949 and by Reger in 1976. Unit characteristics and extents were determined during field visits and by interpreting 1:40,000-scale black-and-white aerial photographs taken in August 1949 and 1:63,360-scale, false-color infrared aerial photographs taken in July 1978, August 1980, and August 1981.
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The data release consists of a single NetCDF file with results from a suite of ice sheet model simulations. We ran with Community Ice Sheet Model (CISM2) with input from models used in the Palaeoclimate Modelling Intercomparison 3 (PMIP3). The NetCDF file contains output from model year 50,000 for a limited number of variables to keep the file size reasonably small. This subset of variables are the ones we focus our analysis and paper on.
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Between 27 and 11 kyr ago, during the last major (Naptowne) glaciation, the northwestern and western Kenai Peninsula and the Cook Inlet trough were covered by ice except for local nunataks and small refugia, like the Caribou Hills. Landforms related to four glacial stades are recognized and paleogeographic maps document ice limits, drainage systems, glacial-impounded lakes, and glaciomarine terraces. Numerous multidisciplinary studies of glacial, vegetation, and insect histories document Holocene climatic changes.
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Alaska Division of Geological & Geophysical Surveys (DGGS) has conducted 1:63,360-scale geologic mapping of the Sagavanirktok B-1 Quadrangle (640 square km�equivalent to four 7.5 minute quadrangles). This mapping project reinterprets micropaleontologic correlations for 17 Sagavanirktok Quadrangle wells, and reprocesses data from the one publicly-available seismic line. Surface geologic mapping, subsurface-to-surface stratigraphic age control, and seismic framework are required to reliably decipher the complex geology of this key area of the Brooks Range. Outcrops within the Sagavanirktok B-1 Quadrangle are the closest surface expressions of Prudhoe Bay source and reservoir rocks. This study yields critical petroleum-related...
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The Alaska Division of Geological & Geophysical Surveys (DGGS), in partnership with the U.S. National Cooperative Geologic Mapping Program, mapped approximately 450 mi2 of the Talkeetna Mountains region of central Alaska at 1:50,000 scale over the course of six weeks in 2014. This area contains significant exposures of Late Triassic mafic volcanics and gabbro sills that have been the focus of region-wide exploration for the Strategic and Critical platinum-group elements (PGEs). The area also exposes numerous inactive and possibly active faults which project through the area of proposed hydropower development. The resulting geologic map offers an improved understanding of the geology, structural history, and mineral...
Tags: 40Ar/39Ar, Aerial Geology, Aerial Photography, Alluvial, Alluvial Deposits, All tags...
Regional-scale groundwater flow modeling of the Fennoscandian shield suggests that groundwater flow can be strongly affected by future climate change and glaciation. We considered variable-density groundwater flow in a 1500-km-long and approximately 10-km-deep cross-section through southern Sweden. Groundwater flow and shield brine transport in the cross-sectional model were analyzed under projected surface conditions for the next 140 ka. Simulations suggest that blockage of recharge and discharge by low-permeability permafrost or cold-based ice causes sinking of brine and consequent freshening of near-surface water in areas of natural discharge. Although recharge of basal meltwater is limited by the requirement...
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At times during the past two million years, glaciers formed in the mountainous part of the Platte River drainage basin. These glaceriers were predominantly valley glaciers, also commonly referred to a s mountain or alpine glaciers. by definition, valley glaciers flow through pre-existing valleys and are bounded by exposed bedrock. the deep valleys and canyons of the map area already existed at the beginning of the Ice Age as a result of regional uplift and subsequent erosion that occured from late Oligocene through Pliocene time. the largest valley glacier in the map area was 45 km long and as much as 600 m thick. During times when Pleistocene glaciers reached their maximum extent, about 10 percent of the mountainous...
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Since the late 1950s, the USGS has maintained a long-term glacier mass-balance program at three North American glaciers. Measurements began on South Cascade Glacier, WA in 1958, expanding to Gulkana and Wolverine glaciers, AK in 1966, and later Sperry Glacier, MT in 2005. The Juneau Icefield Research Program has measured surface mass balance on Lemon Creek and Taku Glacier since the mid-1940s, with USGS providing complimentary seasonal measurements of Lemon Creek beginning in 2014 (JIRP; Pelto and others, 2013). Direct field measurements of point glaciological data are combined with weather and geodetic data to estimate the seasonal and annual mass balance at each glacier in both a conventional and reference surface...
The Pagosa Springs geologic map is of the 7.5-minute quadrangle of the same name. It is located in southwestern Colorado, USA and shows the town of Pagosa Springs. The mapped area is southwest of the San Juan volcanic mountains (Oligocene) and north of the San Juan Basin. All bedrock units exposed in the map area are Upper Cretaceous in age except a minor canyon outcrop of Upper Jurassic rock. Pre-Holocene Quaternary age deposits are mainly alluvial gravels and outwash on terraces. Structure is simple: shale and sandstone beds dip at low angles east to northeast as a broad limb of the north-northwest striking Archuleta Anticline. Three geologic cross sections controlled by drill holes are included and depict Mesozoic...
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Major ecosystems have been mapped and described for the State of Alaska and nearby areas. Ecoregion units are based on newly available datasets and field experience of ecologists, biologists, geologists and regional experts. Recently derived datasets for Alaska included climate parameters, vegetation, surficial geology and topography. Additional datasets incorporated in the mapping process were lithology, soils, permafrost, hydrography, fire regime and glaciation. Thirty two units are mapped using a combination of the approaches of Bailey (hierarchial), and Omernick (integrated). The ecoregions are grouped into two higher levels using a tri-archy-based on climate parameters, vegetation response and disturbance processes....
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Alaska Division of Geological & Geophysical Surveys (DGGS) has conducted 1:63,360-scale geologic mapping of the Sagavanirktok B-1 Quadrangle (640 square km�equivalent to four 7.5 minute quadrangles). This geologic map was produced by merging a bedrock geologic map and a surficial geologic map of the Eagle A-2 Quadrangle. This mapping project reinterprets micropaleontologic correlations for 17 Sagavanirktok Quadrangle wells, and reprocesses data from the one publicly-available seismic line. Surface geologic mapping, subsurface-to-surface stratigraphic age control, and seismic framework are required to reliably decipher the complex geology of this key area of the Brooks Range. Outcrops within the Sagavanirktok B-1...
Regional-scale groundwater flow modeling of the Fennoscandian shield suggests that groundwater flow can be strongly affected by future climate change and glaciation. We considered variable-density groundwater flow in a 1500-km-long and approximately 10-km-deep cross-section through southern Sweden. Groundwater flow and shield brine transport in the cross-sectional model were analyzed under projected surface conditions for the next 140 ka. Simulations suggest that blockage of recharge and discharge by low-permeability permafrost or cold-based ice causes sinking of brine and consequent freshening of near-surface water in areas of natural discharge. Although recharge of basal meltwater is limited by the requirement...
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In cooperation with the Federal Emergency Management Agency, the Pennsylvania Department of Transportation, the Pennsylvania Department of Environmental Protection, and the Susquehanna River Basin Commission, the U.S. Geological Survey (USGS) calculated over 20 different basin characteristics as part of preparing the Pennsylvania StreamStats 2020 application. These datasets are raster representations of various environmental, geological, and land use attributes within the Pennsylvania StreamStats 2020 study area, and will be served in the Pennsylvania StreamStats 2020 application to describe delineated watersheds. The StreamStats application provides access to spatial analytical tools that are useful for water-resources...
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...


    map background search result map search result map Ecoregions of Alaska and Neighboring Territory A Guide to the Late Quaternary History of Northern and Western Kenai Peninsula, Alaska Geologic map of the Dalton Highway (Atigun Gorge to Slope Mountain) area, southern Arctic Foothills, Alaska Geologic map of the Talkeetna Mountains C-4 Quadrangle and adjoining areas, central Alaska Surficial geology of the Dalton Highway (Itkillik-Sagavanirktok rivers) area, southern Arctic foothills, Alaska Geological map of the Sagavanirktok B-1 Quadrangle, eastern North Slope, Alaska Reconnaissance surficial-geologic map of the Sagavanirktok B-1 Quadrangle, eastern North Slope, Alaska Geologic map of the Big Delta A-4 Quadrangle, Alaska Data Release for the Geologic Map of the Pagosa Springs 7.5' Quadrangle, Archuleta County, Colorado Basin Characteristics Rasters for Pennsylvania StreamStats 2020 Data Release - Pleistocene Glaciation in the Upper Platte River Drainage Basin, Colorado Glacier-Wide Mass Balance and Compiled Data Inputs Data Release for the Geologic Map of the Pagosa Springs 7.5' Quadrangle, Archuleta County, Colorado Geologic map of the Big Delta A-4 Quadrangle, Alaska Geologic map of the Dalton Highway (Atigun Gorge to Slope Mountain) area, southern Arctic Foothills, Alaska Surficial geology of the Dalton Highway (Itkillik-Sagavanirktok rivers) area, southern Arctic foothills, Alaska A Guide to the Late Quaternary History of Northern and Western Kenai Peninsula, Alaska Basin Characteristics Rasters for Pennsylvania StreamStats 2020 Glacier-Wide Mass Balance and Compiled Data Inputs Ecoregions of Alaska and Neighboring Territory