Identification_Information: Citation: Citation_Information: Originator: Walser, S.L. Originator: Gillis, R.J. Originator: Bernt, J.D. Originator: Salisbury, J.B. Originator: Diaz, A.V. Originator: Hubbard, T.D. Publication_Date: 2026 Title: Geologic map of the West Susitna area, parts of the Tyonek C-3, C-4, D-4, and D-5 quadrangles, Alaska Geospatial_Data_Presentation_Form: geodatabase Series_Information: Series_Name: Preliminary Interpretive Report Issue_Identification: PIR 2026-1 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 10 p., 2 sheets, scale 1:63,360 Online_Linkage: https://doi.org/10.14509/32075 Description: Abstract: 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 2026-1, prevents surficial and bedrock geology for approximately 500 mi2 of the Tyonek C-3, C-4, D-4, and D-5 quadrangles in western Cook Inlet. These products summarize findings of the West Susitna STATEMAP project, a 1:50,000-scale geologic mapping campaign across an area north of Cook Inlet that has attracted interest for resource development, alternative energy, and recreation. The map area includes approximately 50 miles of the West Susitna Access Corridor, which is proposed to connect Anchorage to the Happy River valley on the western margin of the Susitna Basin. Previous surficial and bedrock geologic mapping in the region has primarily been reconnaissance-level and limited to 1:250,000-scale detail. Field data were collected during a helicopter-supported program from July 16-28, 2024. Surficial geology, initially interpreted through a desktop study in ArcGIS, was verified in the field during the 2024 campaign. The desktop study incorporated new interpretations of remotely sensed imagery combined with previously published geologic mapping and relevant literature. Together, these datasets form the basis for updated geologic unit definitions, geomorphic interpretations, and structural observations presented in this map series. This mapping offers stakeholders information about geologic hazards, including those associated with seismic activity, near the proposed corridor alignment. The resulting surficial and bedrock framework further supports refined interpretations of Quaternary and bedrock geologic history in the western Susitna Basin region. The map is published on two sheets to accommodate its scale and geographic extent. 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 Alaska Division of Geological & Geophysical Surveys website: http://doi.org/10.14509/32075. Purpose: The purpose of this report is to provide new geologic mapping for the Tyonek quadrangles to inform resource planning, hazard assessment, and understanding of the western Susitna Basin, supporting responsible development and infrastructure decisions across Alaska. This updated framework offers statewide benefits by improving evaluations of natural resources, geologic hazards, and land-use opportunities in a region of growing economic interest. 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 Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 2005 Ending_Date: 2025 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -157.494883 East_Bounding_Coordinate: -157.338946 North_Bounding_Coordinate: 60.967378 South_Bounding_Coordinate: 60.902996 Keywords: Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation Theme: Theme_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Theme_Keyword: Alluvial Theme_Keyword: Alluvium Theme_Keyword: Bedrock Theme_Keyword: Bedrock Geologic Map Theme_Keyword: Bedrock Geology Theme_Keyword: Chert Theme_Keyword: Clay Theme_Keyword: Claystone Theme_Keyword: Coal Theme_Keyword: Colluvium Theme_Keyword: Conglomerate Theme_Keyword: Correlation Theme_Keyword: DGGS Theme_Keyword: Dike Theme_Keyword: Drift Theme_Keyword: Elevation Theme_Keyword: Engineering Theme_Keyword: Engineering Geology Theme_Keyword: Erosion Theme_Keyword: Fan Theme_Keyword: Faulting Theme_Keyword: Feldspar Theme_Keyword: Flood Theme_Keyword: Floodplain Theme_Keyword: Fluvial Theme_Keyword: Flysch Theme_Keyword: Gabbro Theme_Keyword: Geologic Theme_Keyword: Geologic Hazards Theme_Keyword: Geologic Map Theme_Keyword: Geologic Materials Theme_Keyword: Geological Process Theme_Keyword: Geology Theme_Keyword: Geomorphology Theme_Keyword: Glacial Theme_Keyword: Glaciation Theme_Keyword: Gravel Theme_Keyword: Hazards Theme_Keyword: Hornblende Theme_Keyword: Igneous Theme_Keyword: Intrusive Theme_Keyword: Landslide Theme_Keyword: Meltwater Theme_Keyword: Metamorphic Theme_Keyword: Metapelite Theme_Keyword: Moraines Theme_Keyword: Mudstone Theme_Keyword: Nonmarine Theme_Keyword: Outcrop Theme_Keyword: Outwash Theme_Keyword: Paludal Theme_Keyword: Peat Theme_Keyword: Pebble Theme_Keyword: Plagioclase Theme_Keyword: Quartz Theme_Keyword: Resources Theme_Keyword: Rocks Theme_Keyword: Sand Theme_Keyword: Sandstone Theme_Keyword: Sediment Theme_Keyword: Sedimentary Theme_Keyword: Silt Theme_Keyword: Siltstone Theme_Keyword: Subbituminous Theme_Keyword: Subsidence Theme_Keyword: Surface Theme_Keyword: Surficial Theme_Keyword: Surficial Deposits Theme_Keyword: Surficial Geologic Map Theme_Keyword: Surficial Geology Theme_Keyword: Talus Theme_Keyword: Tephra Theme_Keyword: Terrace Theme_Keyword: Till Theme_Keyword: Tuff Theme_Keyword: Volcanic Theme_Keyword: Volcaniclastics Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Alexander Creek Place_Keyword: Alexander Lake Place_Keyword: Bates Creek Place_Keyword: Bear Creek Place_Keyword: Beluga Mountain Place_Keyword: Canyon Creek Place_Keyword: Canyon Lake Place_Keyword: Clear Creek Place_Keyword: Contact Creek Place_Keyword: Deep Creek Place_Keyword: Dog Lake Place_Keyword: Hayes River Place_Keyword: Hiline Lake Place_Keyword: Jean Lake Place_Keyword: Onestone Lake Place_Keyword: Quartz Creek Place_Keyword: Rabbit Lake Place_Keyword: Redoubt Mining District Place_Keyword: Sevenmile Lake Place_Keyword: Shell Creek Place_Keyword: Skwentna River Place_Keyword: Snag Creek Place_Keyword: Sucker Lake Place_Keyword: Talachulitna River Place_Keyword: Teepee Lake Place_Keyword: Texas Creek Place_Keyword: Thursday Creek Place_Keyword: Top Lake Place_Keyword: Trail Creek Place_Keyword: Trail Lake Place_Keyword: Wolf Lakes Place_Keyword: Wolverine Creek Place_Keyword: Yentna Mining District Stratum: Stratum_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Stratum_Keyword: Elmendorf Stade Stratum_Keyword: Kahiltna Terrane Stratum_Keyword: Killey Stade Stratum_Keyword: Moosehorn Stade Stratum_Keyword: Naptowne Glaciation Stratum_Keyword: Skilak Stade Temporal: Temporal_Keyword_Thesaurus: Walker, J.D., Geissman, J.W., Bowring, S.A, and Babcock, L.E., comp., 2012, Geologic Time Scale v. 4.0: Geological Society of America Temporal_Keyword: Cretaceous Temporal_Keyword: Early Eocene Temporal_Keyword: Early Miocene Temporal_Keyword: Eocene Temporal_Keyword: Holocene Temporal_Keyword: Jurassic Temporal_Keyword: Late Miocene Temporal_Keyword: Late Paleocene Temporal_Keyword: Middle Miocene Temporal_Keyword: Miocene Temporal_Keyword: Paleocene Temporal_Keyword: Pleistocene Temporal_Keyword: Pliocene 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. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Position: GIS Manager Contact_Address: Address_Type: mailing and physical Address: 3354 College Rd City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: 907-451-5020 Contact_Electronic_Mail_Address: dggsgis@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Data_Set_Credit: This geologic map (or report or conversion or product, etc.) was funded by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G23AC00584, 2023, 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. Cross_Reference: Citation_Information: Originator: Gillis, R.J. Originator: Walser, S.L. Originator: Bernt, J.D. Originator: O'Sullivan, P.B. Publication_Date: 2026 Title: Zircon U-Pb geochronology for bedrock samples from the West Susitna STATEMAP project, southcentral, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2026-8 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 9 p Online_Linkage: https://doi.org/10.14509/31972 Cross_Reference: Citation_Information: Originator: Walser, S.L. Originator: Gillis, R.J. Originator: Bernt, J.D. Originator: Montayne, Simone Publication_Date: 2025 Title: Major-oxide and trace-element analyses of rock samples from the West Susitna area STATEMAP project, southcentral, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2025-21 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 2 p Online_Linkage: https://doi.org/10.14509/31725 Cross_Reference: Citation_Information: Originator: Zechmann, J.M. Originator: Salisbury, J.B. Publication_Date: 2025 Title: Lidar-derived surface elevation data for Dickason Highlands, southcentral Alaska, collected August 14, 2024 Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2025-12 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 10 p Online_Linkage: https://doi.org/10.14509/31536 Cross_Reference: Citation_Information: Originator: Zippi, P.A. Originator: Walser, S.L. Originator: Gillis, R.J. Originator: Montayne, Simone Publication_Date: 2025 Title: Palynological and thermal maturity analysis of outcrop samples from the West Susitna area STATEMAP project, southcentral, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2025-27 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 3 p Online_Linkage: https://doi.org/10.14509/31734 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: 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. Logical_Consistency_Report: All polygon features were topologically validated according to the AK GeMS geologic mapping schema specifications. Completeness_Report: This publication is a DGGS Preliminary Interpretive Report (PIR). A PIR provides timely release of maps and reports with a preliminary interpretation of geology or analytical data. Several scientists familiar with the geology of map area reviewed this product for general readability and logical consistency, but it has not undergone technical peer review. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: 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. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Ekberg, P.G. Originator: Hendricks, M.D. Originator: Athey, J.E. Publication_Date: 2021 Title: AK GeMS symbology: A description of the AK GeMS style file Series_Information: Series_Name: Miscellaneous Publication Issue_Identification: MP 169 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 7 p Online_Linkage: https://doi.org/10.14509/30584 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2021 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: Ekberg, P.G. and others, 2021 Source_Contribution: GIS analysis and digital cartography Source_Information: Source_Citation: Citation_Information: Originator: Hendricks, M.D. Originator: Ekberg, P.G. Originator: Athey, J.E. Originator: Wyatt, W.C. Originator: Willingham, A.L. Originator: Naibert, T.J. Publication_Date: 2021 Title: AK GeMS data dictionary: A description of the Alaska geologic mapping schema Series_Information: Series_Name: Miscellaneous Publication Issue_Identification: MP 170 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 10 p Online_Linkage: https://doi.org/10.14509/30669 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2021 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: Hendricks, M.D. and others, 2021 Source_Contribution: GIS analysis and digital cartography Source_Information: Source_Citation: Citation_Information: Originator: U.S. Geological Survey National Cooperative Geologic Mapping Program Publication_Date: 2020 Title: GeMS (Geologic Map Schema) - A standard format for the digital publication of geologic maps Series_Information: Series_Name: Techniques and Methods Issue_Identification: TM 11-B10 Publication_Information: Publication_Place: United States Publisher: U.S. Geological Survey Other_Citation_Details: 1 p Online_Linkage: https://dggs.alaska.gov/pubs/id/30585 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2020 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020 Source_Contribution: GIS analysis and digital cartography Process_Step: Process_Description: Geologic mapping - DGGS geologists mapped surficial and bedrock geology in the Tyonek C-3, C-4, D-4, and D-5 quadrangles using a combination of desktop analysis and field verification. They developed initial geologic interpretations in ArcGIS from remotely sensed imagery, previously published maps, and relevant literature. From July 16-28, 2024, DGGS geologists conducted helicopter-supported fieldwork to verify geologic units, geomorphic features, and structural observations. They integrated field observations with desktop interpretations to refine geologic unit definitions and produce the final geologic maps. Process_Date: 2023 Process_Step: Process_Description: 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. Process_Date: 2026 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: vector Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geodetic_Model: Horizontal_Datum_Name: NAD83 Ellipsoid_Name: GRS 80 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257222101 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: west_susitna_ak_gems_db Entity_Type_Definition: Geodatabase, layer files, style files, and fonts Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: west_susitna_ak_gems_db Detailed_Description: Entity_Type: Entity_Type_Label: west_susitna_gems_db Entity_Type_Definition: Geodatabase, layer files, style files, and fonts Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: west_susitna_gems_db Detailed_Description: Entity_Type: Entity_Type_Label: west_susitna_gems_geopackage Entity_Type_Definition: SQLite Database file Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: west_susitna_gems_geopackage Detailed_Description: Entity_Type: Entity_Type_Label: west_susitna_gems_shapefile Entity_Type_Definition: Shapefiles and open data files Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: west_susitna_gems_shapefile Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: 907-451-5020 Contact_Facsimile_Telephone: 907-451-5050 Contact_Electronic_Mail_Address: dggspubs@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Contact_Instructions: Please view our website (http://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible. Resource_Description: PIR 2026-1 Distribution_Liability: The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services 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, any failure thereof, or otherwise, and 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. Standard_Order_Process: Non-digital_Form: DGGS publications are available as free online downloads or you may purchase paper hard-copies or digital files on CD/DVD or other digital storage media by mail, phone, fax, or e-mail from the DGGS Fairbanks office. To purchase this or other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Turnaround time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for the exact shipping amount. Fees: see http://dx.doi.org/10.14509/32075 Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: geodatabase Format_Information_Content: geologic map Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://dx.doi.org/10.14509/32075 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20260310 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Simone Montayne Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: 907-451-5020 Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Use_Constraints: If the user has modified this metadata file in any way, the user is obligated to describe the types of modifications the user has made. User specifically agrees not to misrepresent this metadata file, 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. Metadata_Extensions: Online_Linkage: http://www.dggs.alaska.gov/metadata/dggs.ext Profile_Name: dggs metadata extensions