Preliminary geologic map of the Eagle B-1 and C-1 quadrangles, Alaska

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Frequently anticipated questions:


What does this data set describe?

Title:
Preliminary geologic map of the Eagle B-1 and C-1 quadrangles, Alaska
Abstract:
Preliminary geologic map of the Eagle B-1 and C-1 quadrangles, Alaska, Open-File Report 68-103, presents a preliminary geologic map compilation of the Eagle B-1 and C-1 quadrangles in east-central Alaska, showing unconsolidated deposits, sedimentary and igneous units, and a broad suite of metamorphic rocks. Alluvial deposits include floodplain and low-terrace gravel, sand, and silt, and high stream-terrace gravel and sand that are well rounded, well sorted, and locally mantled by windblown silt. Detrital sedimentary rocks consist of non-marine conglomerate, sandstone, and shale containing rounded ultramafic and chert clasts and minor plant fragments. Igneous units include fine-grained basalt dikes with columnar jointing; coarse- to fine-grained granitic rocks dominated by feldspar and quartz; serpentinized ultramafic rocks; and massive quartz-feldspar rock locally associated with muscovite schist. Slightly metamorphosed sedimentary rocks include argillite, phyllite, porous limestone, and minor greenstone. Metamorphic units range from massive to foliated greenstone derived from mafic volcanic rocks to quartz-chlorite-epidote and quartz-mica schists, calcareous schist, quartzite, and marble. Additional units include quartz-graphite schist with interlayered quartzite and mica schist, and amphibolite- to greenschist-facies gneiss and schist containing abundant hornblende and garnet. The map documents lithologic diversity, metamorphic grade, and structural complexity across the quadrangles and provides a geologic framework for regional mapping and resource evaluation. 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/10771.
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?
    Foster, H.L., and Keith, T.C., 1968, Preliminary geologic map of the Eagle B-1 and C-1 quadrangles, Alaska: Open-File Report OF 68-103, U.S. Geological Survey, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -141.509552
    East_Bounding_Coordinate: -140.999789
    North_Bounding_Coordinate: 64.750613
    South_Bounding_Coordinate: 64.249234
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1968
    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: 7
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -141
      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?
    eagle_b1_c1_quad_ak_gems_db
    Geodatabase, layer files, style files, and fonts (Source: DGGS and USGS)
    eagle_b1_c1_quad_gems_db
    Geodatabase, layer files, style files, and fonts (Source: DGGS and USGS)
    eagle_b1_c1_quad_gems_geopackage
    SQLite Database file (Source: DGGS and USGS)
    eagle_b1_c1_quad_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?

This mapping improves Alaska's understanding of bedrock and surficial geology in the Eagle B-1 and C-1 quadrangles by outlining major lithologic units and metamorphic assemblages. It identifies key alluvial deposits, detrital sedimentary rocks, intrusive igneous units, slightly metamorphosed sedimentary rocks, and greenschist- to amphibolite-facies schist and gneiss. The resulting geologic framework supports mineral resource evaluation, land-management planning, and future geologic work across Alaska.

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: 1968 (process 1 of 2)
    Geologic mapping - Geologic mapping was completed by field examination of bedrock and surficial deposits in the Eagle B-1 and C-1 quadrangles. Geologists recorded lithologic characteristics, stratigraphic relations, structural features, and metamorphic textures directly from outcrops. Field observations were combined with reconnaissance mapping from earlier work to refine unit boundaries and update lithologic descriptions. Map units were delineated based on dominant rock type, degree of metamorphism, and sedimentary or igneous features observed in the field. These observations were compiled into a preliminary geologic map showing the distribution of unconsolidated deposits, sedimentary rocks, igneous units, and metamorphic assemblages across the quadrangles.
    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?
    Pinney, D.S., 2001, Engineering - geologic map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2001-3D, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Pinney, D.S., 2001, Surficial-geologic map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2001-3C, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Reger, R.D., Stevens, D.S.P., and Smith, R.L., 2003, Survey of geology, geologic materials, and geologic hazards in proposed access corridors in the Eagle Quadrangle, Alaska: Miscellaneous Publication MP 68, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 5 sheets, scale 1:250,000
    Stevens, D.S.P., 2012, Engineering-geologic map of the Eagle A-1 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2002-1D, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Stevens, D.S.P., and Burns, P.A.C., 2010, Surficial-geologic map of the Eagle A-1 Quadrangle, Fortymile mining district: Preliminary Interpretive Report PIR 2002-1C, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Szumigala, D.J., Newberry, R.J., Werdon, M.B., Athey, J.E., Flynn, R.L., and Clautice, K.H., 2002, Bedrock geologic map of the Eagle A-1 Quadrangle, Fortymile mining district: Preliminary Interpretive Report PIR 2002-1B, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Szumigala, D.J., Newberry, R.J., Werdon, M.B., Athey, J.E., Stevens, D.S.P., Flynn, R.L., Clautice, K.H., and Craw, P.A., 2002, Geologic map of the Eagle A-1 Quadrangle, Fortymile mining district: Preliminary Interpretive Report PIR 2002-1A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Werdon, M.B., Newberry, R.J., and Szumigala, D.J., 2001, Bedrock geologic map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2001-3B, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Werdon, M.B., Newberry, R.J., Szumigala, D.J., and Pinney, D.S., 2001, Geologic map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2001-3A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:63,360

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 68-103
  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 17:24:26 2026