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A physiographically prominent, approximately 40 square km plateau lies roughly 20 km east of Mount Spurr volcano, northwestern Cook Inlet region, Alaska, and comprises the preserved remnant of a volcaniclastic succession, designated in this study as map unit Qvc. Although this readily mappable package of volcaniclastic rocks has been recognized in numerous studies during the past five decades, uncertainties regarding its age and origin have persisted. We describe the general characteristics of the volcaniclastic plateau, provide new age constraints for deposits, present lithofacies descriptions and interpretations of the volcaniclastic strata, and synthesize our observations and lithofacies analysis to propose an...
Valley-fill alluvium deposited from ca. A.D. 1400 to 1880 is widespread in tributaries of the Paria River and is largely coincident with the Little Ice Age epoch of global climate variability. Previous work showed that alluvium of this age is a mappable stratigraphic unit in many of the larger alluvial valleys of the southern Colorado Plateau. The alluvium is bounded by two disconformities resulting from prehistoric and historic arroyo cutting at ca. A.D. 1200–1400 and 1860–1910, respectively. The fill forms a terrace in the axial valleys of major through-flowing streams. This terrace and underlying deposits are continuous and interfinger with sediment in numerous small tributary valleys that head at the base of...
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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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The engineering-geologic map is derived electronically, using Geographic Information System (GIS) software, from the surficial-geologic map of the second segment of the proposed natural gas pipeline corridor through the upper Tanana valley, a 12-mi-wide (19.3-km-wide) area that straddles the Alaska Highway through the upper Tanana River valley from the Robertson River eastward to near Tetlin Junction in the Tanacross Quadrangle (Reger and Hubbard, PIR 2009-6A). Surficial-geologic units were initially identified by interpretation of false-color ~1:65,000-scale infrared aerial photographs taken in July 1978, August 1980, and August 1981 and locally verified by field checking in 2007 and 2008. The map shows the distribution...
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Kasatochi is a small, isolated island volcano in the center of the Aleutian Island chain. It consists of a roughly circular cone approximately 3 km in diameter with a lake-filled central crater that is 1.2 km in diameter and extends from the highest point on the island to sea level. The oldest unit recognized is a thick series of mid-Pleistocene glaciovolcanic deposits consisting of autobrecciated lava, lahars, and volumetrically minor lava masses that we believe to have been emplaced underneath a regional ice cap. This unit is unconformably overlain by several massive Holocene lavas, above which lies a thick sequence of latest-Holocene pyroclastic deposits likely deposited during the crater-forming eruption. The...
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This surficial-geologic map shows the distribution of unconsolidated deposits and undifferentiated bedrock in the Faith Creek area in the Circle A-4, A-5, B-4, and B-5 quadrangles. This map was prepared principally by the interpretation of 1:63,360-scale, false-color, infrared aerial photographs taken in 1979 and 1981 and is locally verified by ground observations during field work in 2007.
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We assessed a construction site in the northern Las Vegas Valley that was initially reported as an "ice age" deposit. Alluvial deposits exposed at the site were inset into the Las Vegas Formation and contained semi-articulated Equus remains. Calibrated radiocarbon dates on two different materials associated with the remains centered on 1957, thus rendering the horse bones as modern.
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The Alaska Division of Geological & Geophysical Surveys (DGGS) has conducted 1:63,360-scale geologic mapping of the Eagle A-1 Quadrangle.The area is part of the 100-year old Fortymile mining district and is located in eastern Alaska near the Alaska-Yukon border. This map illustrates the distribution of a variety of unconsolidated deposits and undifferentiated bedrock in the Eagle A-1 Quadrangle, Fortymile mining district. It was prepared by the interpretation of 1:63,360-scale, false-color, infrared aerial photographs taken from July 1978 through August 1981 and is locally verified by ground observations during field visits.The results should be considered reconnaissance in nature. The dominant unconsolidated deposit...
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During the 2006 field season, the Alaska Division of Geological & Geophysical Surveys conducted remote mapping as part of the Kavik River STATEMAP project.This surficial-geologic mapping was conducted to provide additional detail to the STATEMAP comprehensive geologic mapping as well as to serve as a stand-alone map publication.
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This map illustrates potential near-surface sources of geologic materials that may be useful for construction and other purposes. Field observations indicate that each geologic unit (for example, flood-plain alluvium) has a definite composition or range of composition. Therefore, the presence of material type is interpreted from the distribution of geologic units (Newberry and others, 1996 - PDF96-16). Assignment of Unified Soil Classes (Wagner, 1957) is based on visual observation and interpretation of the likely distribution of the materials; no grain-size analyses were performed. Descriptions of unconsolidated deposits are modified from Pewe and Bel (1975a-d) and Pewe and Bell (1976). This map is generalized...
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This map is a compilation of previously unpublished and published data, as well as from updated field mapping. This publication offers a 1:125,000-scale map sheet accompanied by a booklet containing a summary of the geology, a colored terrane map, map unit descriptions, a summary table listing selected mineral deposits and energy resources, references, and a correlation of map units. The text (in the report) describes the geology and resource potential of a highly mineralized region centered in the Farewell silver-lead-zinc district southeast of McGrath. Potentially important coal resources flanking the Alaska Range are also described in the map area.
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This report provides detailed (1:63,360-scale) mapping of portions of U.S. Geological Survey Circle B-2 (1955), B-3 (1955), B-4 (1952), C-2 (1955), C-3 (1955), and C-4 (1952) quadrangles. The area is part of the Circle mining district and adjacent to the Fairbanks mining district. This report includes detailed geologic, structural, stratigraphic, and geochronologic data. Based on the resulting geologic maps, field investigations, and laboratory materials analyses, the project has also generated derivative maps of geologic construction materials and geologic hazards.
Tags: Aereal, Aerial Photography, Aeromagnetic Survey, Age Dates, Alaska, State of, All tags...
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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...
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This preliminary geologic map of the Fairbanks mining district was mapped at 1:63,360 scale. The report describes the geologic setting, structural geology, earthquake potential, economic geology and the description of bedrock units.
Closure of Glen Canyon Dam in 1963 transformed the Colorado River by reducing the magnitude and duration of spring floods, increasing the magnitude of base flows, and trapping fine sediment delivered from the upper watershed. These changes caused the channel downstream in Glen Canyon to incise, armor, and narrow. This study synthesizes over 45 yr of channel-change measurements and demonstrates that the rate and style of channel adjustment are directly related to both natural processes associated with sediment deficit and human decisions about dam operations. Although bed lowering in lower Glen Canyon began when the first cofferdam was installed in 1959, most incision occurred in 1965 in conjunction with 14 pulsed...
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This bedrock geologic map was produced by using airborne magnetic and electromagnetic surveys, data and notes from several months of fieldwork, geochemical data, and laboratory investigations. These maps are the result of new field investigations in the Eagle A-1 Quadrangle by DGGS in 1999, 2000, and 2001. Field investigations are part of a three-year mapping program to provide geologic ground truth for airborne geophysical surveys flown by DGGS in the Fortymile mining district during 1998.
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This geologic map was produced by merging a bedrock geologic map and a surficial geologic map of the Eagle A-1 Quadrangle. Surficial geologic units were determined by a combination of air photo interpretation and site-specific field investigations. Bedrock geologic units were determined by using a combination of airborne magnetic and electromagnetic surveys, several months of fieldwork, geochemical data, and laboratory investigations. These maps are the result of new field investigations by DGGS in 1999 and 2001.
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This dataset represents a digitized version of the Rawlinson 1993 surficial geologic map of the Flaxman Island and Beechy Point quadrangles, and portions of the Mount Michelson and Harrison Bay quadrangles at 1:63,360 scale. In this newly digitized version of the map, the original maps were scanned, georeferenced, and projected into GIS. Approximately 100-200 typographic and labelling errors from the paper version were corrected with inputs from the original author (corrections completed in 2024). However, this digitized product still adheres to the 1993 interpretation of the surficial geology. Original descriptions of the map units can be found with the 1993 publication (https://doi.org/10.14509/2484). The original...
Valley-fill alluvium deposited from ca. A.D. 1400 to 1880 is widespread in tributaries of the Paria River and is largely coincident with the Little Ice Age epoch of global climate variability. Previous work showed that alluvium of this age is a mappable stratigraphic unit in many of the larger alluvial valleys of the southern Colorado Plateau. The alluvium is bounded by two disconformities resulting from prehistoric and historic arroyo cutting at ca. A.D. 1200?1400 and 1860?1910, respectively. The fill forms a terrace in the axial valleys of major through-flowing streams. This terrace and underlying deposits are continuous and interfinger with sediment in numerous small tributary valleys that head at the base of...


map background search result map search result map A Guide to the Late Quaternary History of Northern and Western Kenai Peninsula, Alaska Preliminary Geologic Map of the Fairbanks Mining District, Alaska Preliminary Derivative Geologic Materials Map of the Fairbanks Mining District, Alaska Geologic map of the Eagle A-1 Quadrangle, Fortymile mining district Bedrock geologic map of the Eagle A-1 Quadrangle, Fortymile mining district, Alaska Surficial-geologic map of the Eagle A-1 Quadrangle, Fortymile mining district Engineering-geologic map of the Alaska Highway Corridor, Robertson River to Tetlin Junction, Alaska Geologic map of the Talkeetna Mountains C-4 Quadrangle and adjoining areas, central Alaska Geology of Kasatochi volcano, Aleutian Islands, Alaska Geologic map of the Circle mining district, Alaska Geologic Map of the Eastern Half of the McGrath Quadrangle, Alaska Surficial-geologic map of the Kavik River area, west-central Mount Michelson Quadrangle, northeastern Brooks Range, Alaska Surficial-geologic map of the northern Fairbanks mining district, Circle Quadrangle, Alaska Surficial-geologic map of the Livengood area, central Alaska Geologic context, age constraints, and sedimentology of a Pleistocene volcaniclastic succession near Mount Spurr volcano, south-central Alaska Radiocarbon dating of an alluvial deposit with associated faunal remains Digitized Legacy Maps of Surficial Geology and Morphology of the Central Arctic Coastal Plain, Alaska Radiocarbon dating of an alluvial deposit with associated faunal remains Geology of Kasatochi volcano, Aleutian Islands, Alaska Geologic context, age constraints, and sedimentology of a Pleistocene volcaniclastic succession near Mount Spurr volcano, south-central Alaska Surficial-geologic map of the Livengood area, central Alaska Surficial-geologic map of the northern Fairbanks mining district, Circle Quadrangle, Alaska Geologic map of the Eagle A-1 Quadrangle, Fortymile mining district Bedrock geologic map of the Eagle A-1 Quadrangle, Fortymile mining district, Alaska Surficial-geologic map of the Eagle A-1 Quadrangle, Fortymile mining district Geologic map of the Talkeetna Mountains C-4 Quadrangle and adjoining areas, central Alaska Geologic map of the Circle mining district, Alaska Surficial-geologic map of the Kavik River area, west-central Mount Michelson Quadrangle, northeastern Brooks Range, Alaska Preliminary Geologic Map of the Fairbanks Mining District, Alaska Preliminary Derivative Geologic Materials Map of the Fairbanks Mining District, Alaska Engineering-geologic map of the Alaska Highway Corridor, Robertson River to Tetlin Junction, Alaska Geologic Map of the Eastern Half of the McGrath Quadrangle, Alaska A Guide to the Late Quaternary History of Northern and Western Kenai Peninsula, Alaska Digitized Legacy Maps of Surficial Geology and Morphology of the Central Arctic Coastal Plain, Alaska