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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...
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...
Aerial photographs of the coastline from Nome to Elim were collected on August 23, 2015. The photographs were processed using Structure-from-Motion (SfM) photogrammetric techniques. Global Positioning System (GPS) checkpoints were collected via a Global Navigation Satellite System (GNSS) survey conducted between August 15 and September 14, 2015. For the purposes of open access to elevation and orthoimagery datasets in coastal regions of Alaska, this collection is being released as a Raw Data File with an open end-user license. This file is a single-band, 32-bit float DSM (digital surface model) which represents surface elevations of buildings, vegetation, and uncovered ground surfaces in meters with 20 cm GSD. The...
In August 2013, a helicopter-based crew photographed approximately 52 miles (84 km) of shoreline near Port Heiden, Alaska, from 7 miles (11 km) northeast of Reindeer Creek, known locally as North Creek, to 10 miles (16 km) southwest of Strogonof Point. During this flight, 1,441 oblique aerial photographs were collected and were spatially referenced using a Garmin Dakota 20 handheld GPS. For a complete description of the image collection and file organization process please see the detailed metadata associated with this Raw Data File.
During 2009 the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted reconnaissance interpretive mapping of permafrost in Alaska Highway Corridor Segment 3, a 12-mi-wide (19.3-km-wide) corridor that straddles the Alaska Highway through the Northway-Tanacross Lowland and the southern Yukon-Tanana Upland from Tetlin Junction to the Canada border. This work was an extension of permafrost mapping done in Alaska Highway Corridor Segment 1 from Delta Junction to Dot Lake in the Big Delta and Mt. Hayes Quadrangles during 2006-2007 and Alaska Highway Corridor Segment 2 from the Robertson River to Tetlin Junction in the Tanacross Quadrangles during 2008. Primarily, we inferred the extent of permafrost and...
The State of Alaska Division of Geological & Geophysical Surveys (DGGS) produced a digital surface model (DSM) and an orthorectified aerial optical image mosaic (orthoimagery) of the Resurrection Bay watershed, surrounding the city of Seward in south-central Alaska. Aerial photographs and Global Navigation Satellite System (GNSS) data were collected on August 13, 2015, and were processed using Structure-from-Motion (SfM) photogrammetric techniques to create the DSM and orthoimagery. All data are projected in UTM Zone 6 North (meters) using the NAD83 (2011; EPSG 26906) horizontal datum and NAVD88 (Geoid12A; EPOCH 2010.00) vertical datum. The project was part of an ongoing investigation of the impact of flooding,...
During 2008-2010, the Alaska Division of Geological & Geophysical Surveys continued a program, begun in 2006, of reconnaissance mapping of surficial geology in the proposed natural-gas pipeline corridor through the upper Tanana River valley, a 12-mi-wide (19.3-km-wide) area that straddles the Alaska Highway through the upper Tanana River valley from the western boundaries of the Tanacross B-6 and C-6 Quadrangles near the mouth of the Robertson River eastward to the eastern boundaries of the Tanacross A-4 and B-4 Quadrangles near Tetlin Junction. Mapping during 2008-2010 in the Tanacross Quadrangle linked with mapping of surficial geology completed in the Big Delta and Mt. Hayes quadrangles in 2006-2007. Surficial...
Aerial photographs of the coastline from Wales to Teller were collected on August 27, 2015 - August 28, 2015. The photographs were processed using Structure-from-Motion (SfM) photogrammetric techniques. Global Positioning System (GPS) checkpoints were collected via a Global Navigation Satellite System (GNSS) survey conducted between August 15 and September 14, 2015. For the purposes of open access to elevation and orthoimagery datasets in coastal regions of Alaska, this collection is being released as a Raw Data File with an open end-user license. Orthoimages contain 4-band, 8-bit, unsigned raster data (red/green/blue/no data; file format-GeoTIFF; source-Fairbanks Fodar) with 20 cm GSD. No-data values are found...
The State of Alaska Division of Geological & Geophysical Surveys (DGGS) produced a digital surface model (DSM) and an orthorectified aerial optical image mosaic (orthoimagery) of the Resurrection Bay watershed, surrounding the city of Seward in south-central Alaska. Aerial photographs and Global Navigation Satellite System (GNSS) data were collected on August 13, 2015, and were processed using Structure-from-Motion (SfM) photogrammetric techniques to create the DSM and orthoimagery. All data are projected in UTM Zone 6 North (meters) using the NAD83 (2011; EPSG 26906) horizontal datum and NAVD88 (Geoid12A; EPOCH 2010.00) vertical datum. The project was part of an ongoing investigation of the impact of flooding,...
This report presents the findings of a geologic and geotechnical evaluation of a landslide at the Yukon River bridge (the E.L. Patton Bridge). The Yukon River bridge landslide occurred in fall 2012 between approximately 375 and 575 feet west of the bridge. Although there was no damage to the bridge foundation, the landslide's close proximity to the bridge and concerns over additional failures prompted multiple evaluations, including landslide documentation, drainage assessments, and geotechnical studies. This report was prepared to convey the general characteristics of the rock mass, characteristics of rock discontinuities, and the geomorphic expression of the 2012 landslide in the vicinity of the bridge. We determined...
Aerial photographs of the coastline from Wales to Teller were collected on August 27, 2015 - August 28, 2015. The photographs were processed using Structure-from-Motion (SfM) photogrammetric techniques. Global Positioning System (GPS) checkpoints were collected via a Global Navigation Satellite System (GNSS) survey conducted between August 15 and September 14, 2015. For the purposes of open access to elevation and orthoimagery datasets in coastal regions of Alaska, this collection is being released as a Raw Data File with an open end-user license. This file is a single-band, 32-bit float DSM (digital surface model) which represents surface elevations of buildings, vegetation, and uncovered ground surfaces in meters...
Aerial photographs of the coastline from Nome to Elim were collected on August 23, 2015. The photographs were processed using Structure-from-Motion (SfM) photogrammetric techniques. Global Positioning System (GPS) checkpoints were collected via a Global Navigation Satellite System (GNSS) survey conducted between August 15 and September 14, 2015. For the purposes of open access to elevation and orthoimagery datasets in coastal regions of Alaska, this collection is being released as a Raw Data File with an open end-user license. Orthoimages contain 4-band, 8-bit, unsigned raster data (red/green/blue/no data; file format-GeoTIFF; source-Fairbanks Fodar) with 20 cm GSD. No-data values are found in band 4 or shown as...
This report provides detailed (1:63,360-scale) mapping of the Tanana A-1 and A-2 quadrangles (500 square miles; equivalent to eight 7.5-minute quadrangles). The area is part of the Manley Hot Springs-Tofty mining districts and adjacent to the Rampart mining district to the south of the Tanana B-1 Quadrangle. This report includes detailed bedrock, structural, and stratigraphic data. The Tanana A-1 and A-2 Quadrangles and surrounding area comprise several isolated mountainous ridges in the western Yukon-Tanana Upland of interior Alaska.
The Geologic Photos of Alaska database and online application contains photographs taken during and in support of Alaska Division of Geological & Geophysical Surveys (DGGS) projects. These photographs primarily document field sites and geomorphology statewide, usually in remote locations that are often impossible or prohibitively expensive to revisit. The database (http://maps.dggs.alaska.gov/photodb/) includes a variety of images such as field photos, photos of samples, and photomicrographs (photograph of a microscopic object) taken with the aid of a microscope.
During 2008 the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted reconnaissance interpretive mapping of permafrost in Alaska Highway Corridor Segment 2, a 12-mi-wide (19.3-km-wide) corridor that straddles the Alaska Highway through the upper Tanana River valley from the eastern boundary of the Mt. Hayes Quadrangle to the eastern edge of the Tanacross Quadrangle. This work was an extension of permafrost mapping done in Alaska Highway Corridor Segment 1 from Delta Junction to Dot Lake in the Big Delta and Mt. Hayes Quadrangles during 2006-2007. Primarily, we inferred the extent of permafrost and ice content by interpreting ~1:65,000-scale, false-color infrared aerial photographs taken in July 1978,...
During 2009, the Alaska Division of Geological & Geophysical Surveys continued a program, begun in 2006, of reconnaissance mapping of surficial geology in the proposed natural-gas pipeline corridor through the upper Tanana River valley. The study area is a 12-mi-wide (19.3-km-wide) area that straddles the Alaska Highway from the western boundaries of the Tanacross B-3 and A-3 quadrangles near Tetlin Junction eastward to the eastern boundaries of the Nabesna D-1 and C-1 quadrangles along the Canada border. Mapping during 2008-2009 in the Tanacross and Nabesna quadrangles linked with the mapping completed in the Tanacross, Big Delta and Mt. Hayes quadrangles in 2006-2008. Surficial geology was initially mapped in...
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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