This 1:50,000 scale geologic map describes the distribution of unconsolidated deposits, identifies local geologic hazards, and provides information about the depositional environment and basic engineering properties of common surficial-geologic materials in and around Shaktoolik, Alaska. Map units are the result of combined field observations and aerial imagery interpretation. A suite of local ground observations were collected over a two-week period in July 2011 by a helicopter-supported team of DGGS geologists and collaborators. Field investigations included soil test pits, sample collection, soil and rock description, oblique aerial photography, and documentation of landscape morphology.

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 of surficial-geologic and bedrock units grouped genetically with common properties that are typically significant for engineering applications.

The engineering-geologic map, on two sheets, is derived electronically from the surficial-geologic map of the initial segment of the proposed natural gas pipeline corridor through the upper Tanana valley (Reger and others, PIR 2008-3a) using Geographic Information System (GIS) software. Surficial-geologic units were initially identified by interpretation of false-color ~1:63,000-scale infrared aerial photographs taken in July 1978, August 1980, and August 1981 and locally verified by field checking in 2006 and 2007. The map shows the distribution of surficial-geologic and bedrock units grouped genetically with common properties that are typically significant for engineering applications.

Landslide hazard susceptibility mapping in Haines, Alaska, Report of Investigation 2024-8, provides a map and database of historical and prehistoric slope failures, maps of shallow and deep-seated landslide susceptibility, and a map of simulated debris flow runouts for the city and borough of Haines, Alaska. This work was prompted by the deadly Beach Road landslide that occurred on December 2, 2020, in Haines, Alaska, which highlights the significant safety and financial risks posed by slope failures to people and infrastructure. To better inform the Haines Borough of their potential landslide hazards and increase the city's hazard resiliency, the Alaska Division of Geological & Geophysical Surveys (DGGS) developed maps of historical and prehistorical slope failures, shallow landslide susceptibility, and modeled debris flow runouts. DGGS staff created a shallow landslide susceptibility map following protocols like those developed by the Oregon Department of Geology and Mineral Industries, which includes incorporating landslide inventory data, geotechnical soil properties, and lidar-derived topographic slope to calculate the Factor of Safety (FOS), which serves as a proxy for landslide susceptibility. Debris flow runout extents were generated using the model Laharz, which simulates runout extents based on catchment-specific physical parameters (e.g., hypothetical sediment volumes). Data from these analyses are collectively intended to depict locations where landslides are relatively more likely to occur or are relatively more likely to travel. The results provide important hazard information that can help guide planning and future risk investigations. The maps are not intended to predict slope failures and are site-specific; detailed investigations should be conducted before development in vulnerable areas. Results are for informational purposes and are not intended for legal, engineering, or surveying uses. These data and the interpretive maps and report are available from the DGGS website: http://doi.org/10.14509/31309.

During 2006 and 2007 the Alaska Division of Geological & Geophysical Surveys conducted reconnaissance surficial-geologic mapping in segment 1 of the Alaska Highway corridor, which straddles the Alaska Highway through the Tanana River valley from Delta Junction to the eastern boundary of the Mt. Hayes Quadrangle. Surficial-geologic deposits were initially mapped by interpreting ~1:63,360-scale, false-color infrared aerial photographs taken in August 1980 and field verified in 2006-2007.

Report of Investigation 2018-6, Geologic map of the Umiat-Gubik area, central North Slope, Alaska, provides a 1:63,360-scale geologic map of the hydrocarbon-bearing Umiat-Gubik area of the central North Slope, Alaska, spans approximately 2,100 km2 at the northern extent of the Brooks Range foothills fold-and-thrust belt in the Colville foreland basin. This geologic map was prepared through assimilation of field observations, aerial and satellite imagery, seismic-reflection data, and well logs. Near-surface formation picks were available or derived for most of the area's 24 exploration wells, and two cross-sections were constructed along lines of section that are constrained at depth by our interpretations of publicly available two-dimensional seismic data. The mapped area hosts exposures of Upper Cretaceous strata in the Nanushuk, Seabee, Tuluvak, Schrader Bluff, and Prince Creek Formations, constituting an approximately 2-km-thick succession that crops out discontinuously in the low-relief, tundra-mantled region. This part of the siliciclastic Brookian megasequence stratigraphy comprises principally shallow-marine deposits. Our work benefits from and reflects recent sequence-stratigraphic advances that better constrain how this part of the Colville basin continued to fill by a northeastward prograding clastic wedge during Late Cretaceous time, with the exposed stratigraphy recognized as basin-scale topset units. A series of east- to east-southeast-trending, km-scale wavelength, gentle folds are mapped in the area. Anticlines are locally breached by thrusts and interpreted to be folded above faulted and penetratively deformed mid-Cretaceous Torok Formation. Undeveloped, sub-commercial (as of this writing) petroleum accumulations occur along doubly plunging anticlinal traps at three long-recognized fields in the map area: Umiat (mostly oil), Gubik (gas), and East Umiat (gas). The Umiat oil field structural culmination is modified by thrust faults that breach the surface, and the East Umiat gas field is associated with a north-dipping back-thrust that is evident in seismic data and cuts across the Upper Cretaceous stratigraphy; thrust faults near the Gubik gas field lie within and below the Torok Formation. Various interpretations have previously been published for some of the area's structures, with important implications for petroleum trap geometries in the gas-prone foothills region. We present new data and interpretations that support the inference of a principal, south-dipping thrust fault that breaches the north limb of Umiat anticline near Umiat. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: http://doi.org/10.14509/30099.

Surficial-geologic map of the Salcha River-Pogo area, Big Delta Quadrangle, Alaska, Report of Investigation 2004-1C, illustrates the distribution of unconsolidated deposits and undifferentiated bedrcok units in the Salcha River-Pogo area. It was prepared by interpretation of 1:63,360-scale false-color infrared aerial photographs taken July 1978, July 1979, and August 1981, and is locally verified by ground observations during field visits. Based on the generally subdued nature of glacial deposits in the field area, we speculate that undifferentiated glacial deposits mapped are composed of material deposited by the Charley River (early? Pleistocene), Mt. Harper (middle? Pleistocene), and Eagle (early? Wisconsin) glaciations (Weber, 1986). It is highly unlikely that the area was glaciated during Salcha (late Wisconsin) or Ramshorn (Holocene) glaciations. The northeast-southwest-trending Shaw Creek fault crosses the study area. Although the fault was observed on 1:63,360-scale, false-color, infrared aerial photographs, we were unable to document offset on surficial geologic units. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: http://doi.org/10.14509/18001.

Geologic Investigations Series Map 2788, Geologic map of the Big Delta B-2 Quadrangle, east-central Alaska, provides detailed (1:63,360-scale) geologic mapping of the U.S. Geological Survey (USGS) Big Delta B-2 quadrangle. This data release is a conversion of the originating geospatial data published by the USGS and may include minor modifications necessary for schema compliance. The dataset contains geologic, structural, stratigraphic, and geochronologic data organized according to the GeMS and AK GeMS mapping schemas. The geodatabase and ESRI fonts and style files are available from the DGGS website: https://dggs.alaska.gov/pubs/id/13143.