Alaska Geologic Mapping Schema (AK GeMS) multi-map repository database

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Frequently anticipated questions:


What does this data set describe?

Title:
Alaska Geologic Mapping Schema (AK GeMS) multi-map repository database
Abstract:
Alaska Geologic Mapping Schema (AK GeMS) multi-map repository database, Digital Data Series 24, comprises several key components working together to ensure that the Alaska Division of Geological & Geophysical Surveys (DGGS) efficiently produces high-quality, standards-based geologic maps. A critical component of this system is our AK GeMS Multi-Map Repository Database, which combines the individual geologic map data into a single GIS-based enterprise geodatabase. This Digital Data Series (DDS) allows users to download file geodatabase date-stamped snapshots of our AK GeMS Multi-Map repository database. The complete report, geodatabase, and ESRI fonts and style files are available from the Alaska Division of Geological & Geophysical Surveys website: http://doi.org/10.14509/31706.
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?
    Hendricks, M.D., Rivera, P.G., Steinleitner, A.M., Macpherson, A.E., Montayne, Simone, and Wyatt, W.C., 2025, Alaska Geologic Mapping Schema (AK GeMS) multi-map repository database: Digital Data Series DDS 24, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 2 p.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -180.000000
    East_Bounding_Coordinate: 180.000000
    North_Bounding_Coordinate: 71.392029
    South_Bounding_Coordinate: 51.217293
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 2020
    Ending_Date: 2025
    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?
      The map projection used is Alaska Albers.
      Projection parameters:
      Standard_Parallel: 55.0
      Standard_Parallel: 65.0
      Longitude_of_Central_Meridian: -154.0
      Latitude_of_Projection_Origin: 50.0
      False_Easting: 0
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.0000000030536018158500163
      Ordinates (y-coordinates) are specified to the nearest 0.0000000030536018158500163
      Planar coordinates are specified in meters
      The horizontal datum used is NAD83.
      The ellipsoid used is GRS 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222101.
  7. How does the data set describe geographic features?
    ak_gems_mm_db_06_May_2025_ak_gems_db_pkg
    Geodatabase, layer files, style files, and fonts (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?
    DGGS greatly appreciates the many people who have helped us refine Alaska's extended database schemas through presentations and discussions. We also thank our funding sources for helping to make this work possible. This report was funded in part by the Environmental Protection Agency Exchange Network grant OS 836470-01, USGS National Geological Map Database Cooperative Agreement award number G19AC00411, USGS National Cooperative Geologic Mapping Program under StateMap award number G20AC00367, 2020, 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. Geologic map conversion to the GeMS standard was funded by the USGS National Cooperative Geologic Mapping Program under StateMap award number G20AC00367, 2020, 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?

To meet local geologic mapping requirements, the Alaska Division of Geological & Geophysical Surveys (DGGS) designed the Alaska Geologic Mapping Schema (AK GeMS), which is an extension to the Geologic Mapping Schema (GeMS) (U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020). To meet these design considerations, AK GeMS supports various geodatabase implementations as part of the overall Alaska DGGS Geologic Mapping System.

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: 2025 (process 1 of 2)
    Database development - DGGS staff developed the Alaska Geologic Mapping Schema (AK GeMS) as an extension of the national Geologic Mapping Schema (GeMS) published by the U.S. Geological Survey in 2020. They based the AK GeMS multi-map design on the earlier single-map version (Hendricks et al., 2024) and optimized it to manage large volumes of data and support multiple geologic map products. DGGS consolidated individual map data into an enterprise-level geodatabase and periodically exported date-stamped file geodatabase snapshots. They packaged these snapshots using their standardized GeMS data format to ensure consistency and usability. Hendricks and others. (2023) documented the database development process and outlined ongoing maintenance tasks to support long-term functionality.
    Date: 2025 (process 2 of 2)
    GIS analysis and digital cartography - This data distribution package's geologic and geographic features were organized and attributed according to the AK GeMS geologic mapping schema. The legacy data were programmatically transformed to provide download options in three formats: (1) an AK GeMS data package that includes the complete AK GeMS database and associated files, (2) a GeMS data package that is a conversion of the AK GeMS database into the base GeMS standard published by the USGS, and (3) a shapefile data package that includes two simple shapefile representations of the data. Data sources used in this process:
    • Ekberg, P.G. and others, 2021
    • Hendricks, M.D. and others, 2021
    • U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020
  3. What similar or related data should the user be aware of?
    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
    Hendricks, M.D., Athey, J.E., Montayne, Simone, Wyatt, W.C., Macpherson, A.E., and Buchanan, Wes, 2024, Alaska GeMS geologic mapping system status report: January 1, 2016-June 30, 2023: Miscellaneous Publication MP 175, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 33 p
    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
    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: Miscellaneous Publication MP 170 v. 2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 13 p
    Macpherson, A.E., Hendricks, M.D., and Athey, J.E., 2024, AK GeMS Symbology: A description of the AK GeMS Style File: Miscellaneous Publication MP 169 v. 2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 6 p

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 part of the DGGS Digital Data Series. Reports in this series present regularly updated compilations of analytical data, geologic map features, geologic information, photographs, geophysical survey areas, and more. The report and accompanying data have been reviewed by project staff for logical consistency; however, the features in the dataset are entirely derived from previously published works. Information presented in this release is subject to revision.
  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? DDS 24
  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: 08-Sep-2025
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 Mon Sep 08 18:54:29 2025