Reconnaissance engineering geology for the selection of highway route from Talkeetna to McGrath, Alaska

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Frequently anticipated questions:

What does this data set describe?

Title:
Reconnaissance engineering geology for the selection of highway route from Talkeetna to McGrath, Alaska
Abstract:
Reconnaissance engineering geology for the selection of highway route from Talkeetna to McGrath, Alaska, Open-File Report 61-169, evaluates a potential highway corridor between Talkeetna and McGrath to support planning for expansion of Alaska's highway system. Field checks were completed in 1959 and 1960, and aerial photographs were used to map bedrock and surficial deposits throughout the corridor. The study provides a general geologic basis for identifying possible road routes and focuses on conditions that may influence construction. The area includes parts of the lower Susitna River valley, a narrow band across the Alaska Range, and a broad region to the northwest. Two eastern access options were examined: a route west from Talkeetna along the Petersville Road toward Rainy Pass, and a route west from Flat Lake that parallels the historic Iditarod Trail along the Susitna, Yentna, and Skwentna Rivers. Bedrock interpretation draws on published geologic reports, and geologic information for the Farewell-McGrath area is based largely on the work of Arthur T. Fernald. Geologic units were delineated primarily from aerial photographs and transferred to topographic maps; boundaries are approximate. Surficial materials important for engineering evaluation include flood plain and terrace alluvium, alluvial fans and aprons, bog deposits, talus and localized mass-movement debris, active and inactive glacial outwash, outwash fans, alpine and end moraines, multiple varieties of ground moraine, silt and colluvium over bedrock, poorly and well consolidated sedimentary rocks, granitic intrusive rocks, and volcanic rocks. Glaciation strongly affected the Susitna drainage, where large glaciers once filled the valley and overtopped nearby hills and low mountains. Older drift is commonly mantled by windblown silt. In the Kuskokwim drainage, valley glaciers advanced roughly 20 miles from the mountain front, leaving arcuate end moraines and outwash fans. Eolian sand and silt are widespread north of the range. Permafrost is sporadic in the Susitna area but widespread on the Kuskokwim side, where it must be considered in road design. Seasonal frost action can be intense in poorly drained, fine-grained sediments throughout the corridor. The dataset provides geologic, structural, stratigraphic, and geochronologic information organized according to the GeMS and AK GeMS mapping schemas. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: https://dggs.alaska.gov/pubs/id/10671.
Supplemental_Information:
This geodatabase is organized according to the AK GeMS mapping schema Hendricks, M.D., Macpherson, A.E., Athey, J.E., Wyatt, W.C., Montayne, Simone, Buchanan, Wes, Rivera, P.G., and Steinleitner, A.M., 2024, AK GeMS data dictionary: A description of the Alaska geologic mapping schema: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 170 v. 2, 13 p. https://doi.org/10.14509/31172. The distribution package includes ESRI fonts and style files, along with usage instructions. Further documentation of the symbology is provided by Ekberg, P.G., Hendricks, M.D., and Athey, J.E., 2021, AK GeMS symbology: A description of the AK GeMS style file: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 169, 7 p. https://doi.org/10.14509/30584.
  1. How might this data set be cited?
    Weber, F.R., 1961, Reconnaissance engineering geology for the selection of highway route from Talkeetna to McGrath, Alaska: Open-File Report OF 61-169, U.S. Geological Survey, United States.

    Online Links:

    Other_Citation_Details: 2 sheets, scale 1:250,000
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -155.780385
    East_Bounding_Coordinate: -149.845804
    North_Bounding_Coordinate: 63.026715
    South_Bounding_Coordinate: 61.429066
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1960
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: geodatabase
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a vector data set.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 5
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -153
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000.000000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest .00000001
      Ordinates (y-coordinates) are specified to the nearest .00000001
      Planar coordinates are specified in Meters
      The horizontal datum used is NAD27.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.9786982.
  7. How does the data set describe geographic features?
    talkeetna_to_mcgrath_ak_gems_db
    Geodatabase, layer files, style files, and fonts (Source: DGGS and USGS)
    talkeetna_to_mcgrath_gems_db
    Geodatabase, layer files, style files, and fonts (Source: DGGS and USGS)
    talkeetna_to_mcgrath_gems_geopackage
    SQLite Database file (Source: DGGS and USGS)
    talkeetna_to_mcgrath_gems_shapefile
    Shapefiles and open data files (Source: DGGS and USGS)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
    This map was converted to GeMS or digitized into GeMS by Kinney Engineering, LCC., quality controlled, and then finalized by DGGS staff (Chris Wyatt). Ally M. Steinleitner implemented final database quality control and packaging. This geologic map (or report or conversion or product, etc.) was funded by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G24AC00521, 2024, and the State of Alaska General Fund. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.
  3. To whom should users address questions about the data?
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    dggspubs@alaska.gov
    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.

Why was the data set created?

The purpose of this study was to supply early geologic and engineering information needed to evaluate possible highway routes between Talkeetna and McGrath. The work used aerial photograph interpretation and field checks completed in 1959 and 1960 to identify terrain conditions that could have affected road construction. The results supported the State of Alaska by helping assess long-range transportation options across remote terrain, improving planning for future access to communities, resource areas, and regional corridors.

How was the data set created?

  1. From what previous works were the data drawn?
    Ekberg, P.G. and others, 2021 (source 1 of 3)
    Ekberg, P.G., Hendricks, M.D., and Athey, J.E., 2021, AK GeMS symbology: A description of the AK GeMS style file: Miscellaneous Publication MP 169, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 7 p
    Type_of_Source_Media: paper
    Source_Contribution: GIS analysis and digital cartography
    Hendricks, M.D. and others, 2021 (source 2 of 3)
    Hendricks, M.D., Ekberg, P.G., Athey, J.E., Wyatt, W.C., Willingham, A.L., and Naibert, T.J., 2021, AK GeMS data dictionary: A description of the Alaska geologic mapping schema: Miscellaneous Publication MP 170, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 10 p
    Type_of_Source_Media: paper
    Source_Contribution: GIS analysis and digital cartography
    U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020 (source 3 of 3)
    U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020, GeMS (Geologic Map Schema) - A standard format for the digital publication of geologic maps: Techniques and Methods TM 11-B10, U.S. Geological Survey, United States.

    Online Links:

    Other_Citation_Details: 1 p
    Type_of_Source_Media: paper
    Source_Contribution: GIS analysis and digital cartography
  2. How were the data generated, processed, and modified?
    Date: 1960 (process 1 of 2)
    Geologic mapping - Aerial photographs were examined to identify bedrock, surficial deposits, glacial features, and terrain conditions relevant to highway route evaluation. Photo interpretation was supported by field checks completed in 1959 and 1960. Geologic units were delineated on the photographs, transferred to topographic maps, and classified according to engineering significance. Surficial materials were grouped into alluvial, bog, colluvial, mass-movement, glacial, eolian, and bedrock units to support assessment of construction conditions. Boundaries were considered approximate due to the reconnaissance nature of the work.
    Date: 2026 (process 2 of 2)
    Data packaging - DGGS organized and attributed the geologic and geographic features according to the AK GeMS schema, then programmatically transformed the data into four distribution formats: (1) an AK GeMS data package containing the full database and supporting files, (2) a GeMS data package converted to the USGS base standard, (3) a SQLite database file, and (4) a simplified shapefile package with shapefile representations of the data.
  3. What similar or related data should the user be aware of?
    Bundtzen, T.K., and Laird, G.M., 1980, Preliminary geology of the McGrath - upper Innoko River area, western interior Alaska: Alaska Open-File Report AOF 134, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 39 p., 2 sheets
    Bundtzen, T.K., and Laird, G.M., 1983, Geologic map of the McGrath D-6 Quadrangle, Alaska: Professional Report PR 79, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic map of the eastern half of the McGrath Quadrangle, Alaska: Report of Investigation RI 97-14A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 34 p., 1 sheet, scale 1:125,000
    Kline, J.T., and Pinney, D.S., 1997, Derivative map of the geologic materials and hazards in the eastern half McGrath Quadrangle, Alaska: Report of Investigation RI 97-14B, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:125,000
    Walser, S.L., Gillis, R.J., Bernt, J.D., Salisbury, J.B., Diaz, A.V., and Hubbard, T.D., 2026, Geologic map of the West Susitna area, parts of the Tyonek C-3, C-4, D-4, and D-5 quadrangles, Alaska: Preliminary Interpretive Report PIR 2026-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 10 p., 2 sheets, scale 1:50,000

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Attribute fields within each feature class are populated using the map symbology and corresponding applicable values from the GeMS and AK GeMS specifications. When known, certainty in attribute interpretation is indicated in the relevant fields. Attribute accuracy varies throughout the map and is scale-dependent.
  2. How accurate are the geographic locations?
    Certainty in feature boundaries or location varies throughout the map. Data fields within each feature class and the accompanying orientation and location confidence lookup tables record the authors' degree of confidence in the location of applicable features.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This publication is a U.S. Geological Survey Open-File Report (OF), which provide rapid public release of scientific information. The series includes interpretive reports, maps, supporting data, preliminary findings, interim computer programs, user guides, and bibliographies.
  5. How consistent are the relationships among the observations, including topology?
    All polygon features were topologically validated according to the AK GeMS geologic mapping schema specifications.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints:
This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
  1. Who distributes the data set? (Distributor 1 of 1)
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    dggspubs@alaska.gov
    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set? OF 61-169
  3. What legal disclaimers am I supposed to read?
    The State of Alaska makes no expressed or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 01-Sep-2026
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Attn: Simone Montayne
Metadata Manager
3354 College Road
Fairbanks, AK
USA

(907)451-5020 (voice)
(907)451-5050 (FAX)
dggspubs@alaska.gov
Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:
Generated by mp version 2.9.50 on Tue Sep 01 17:48:30 2026