Walser, S.L.Gillis, R.J.Bernt, J.D.Salisbury, J.B.Diaz, A.V.Hubbard, T.D.2026geodatabasePreliminary Interpretive ReportPIR 2026-1Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys10 p., 2 sheets, scale 1:63,360https://doi.org/10.14509/32075Geologic 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, presents 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.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.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/10.14509/3058420052025ground conditionCompleteNone planned-157.494883-157.33894660.96737860.902996ISO 19115 Topic CategorygeoscientificInformationAlaska Division of Geological & Geophysical SurveysAlluvialAlluviumBedrockBedrock Geologic MapBedrock GeologyChertClayClaystoneCoalColluviumConglomerateCorrelationDGGSDikeDriftElevationEngineeringEngineering GeologyErosionFanFaultingFeldsparFloodFloodplainFluvialFlyschGabbroGeologicGeologic HazardsGeologic MapGeologic MaterialsGeological ProcessGeologyGeomorphologyGlacialGlaciationGravelHazardsHornblendeIgneousIntrusiveLandslideMeltwaterMetamorphicMetapeliteMorainesMudstoneNonmarineOutcropOutwashPaludalPeatPebblePlagioclaseQuartzResourcesRocksSandSandstoneSedimentSedimentarySiltSiltstoneSubbituminousSubsidenceSurfaceSurficialSurficial DepositsSurficial Geologic MapSurficial GeologyTalusTephraTerraceTillTuffVolcanicVolcaniclasticsAlaska Division of Geological & Geophysical SurveysAlexander CreekAlexander LakeBates CreekBear CreekBeluga MountainCanyon CreekCanyon LakeClear CreekContact CreekDeep CreekDog LakeHayes RiverHiline LakeJean LakeOnestone LakeQuartz CreekRabbit LakeRedoubt Mining DistrictSevenmile LakeShell CreekSkwentna RiverSnag CreekSucker LakeTalachulitna RiverTeepee LakeTexas CreekThursday CreekTop LakeTrail CreekTrail LakeWolf LakesWolverine CreekYentna Mining DistrictAlaska Division of Geological & Geophysical SurveysElmendorf StadeKahiltna TerraneKilley StadeMoosehorn StadeNaptowne GlaciationSkilak StadeWalker, J.D., Geissman, J.W., Bowring, S.A, and Babcock, L.E., comp., 2012, Geologic Time Scale v. 4.0: Geological Society of AmericaCretaceousEarly EoceneEarly MioceneEoceneHoloceneJurassicLate MioceneLate PaleoceneMiddle MioceneMiocenePaleocenePleistocenePlioceneThis 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).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.Alaska Division of Geological & Geophysical SurveysGIS Managermailing and physical

3354 College Rd

FairbanksAK99709-3707USA907-451-5020dggsgis@alaska.gov8 am to 4:30 pm, Monday through Friday, except State holidaysThis 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.Gillis, R.J.Walser, S.L.Bernt, J.D.O'Sullivan, P.B.2026Raw Data FileRDF 2026-8Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys9 phttps://doi.org/10.14509/31972Walser, S.L.Gillis, R.J.Bernt, J.D.Montayne, Simone2025Raw Data FileRDF 2025-21Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys2 phttps://doi.org/10.14509/31725Zechmann, J.M.Salisbury, J.B.2025Raw Data FileRDF 2025-12Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys10 phttps://doi.org/10.14509/31536Zippi, P.A.Walser, S.L.Gillis, R.J.Montayne, Simone2025Raw Data FileRDF 2025-27Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys3 phttps://doi.org/10.14509/31734Attribute 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.All polygon features were topologically validated according to the AK GeMS geologic mapping schema specifications.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.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.Ekberg, P.G.Hendricks, M.D.Athey, J.E.2021Miscellaneous PublicationMP 169Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys7 phttps://doi.org/10.14509/30584paper2021publication dateEkberg, P.G. and others, 2021GIS analysis and digital cartographyHendricks, M.D.Ekberg, P.G.Athey, J.E.Wyatt, W.C.Willingham, A.L.Naibert, T.J.2021Miscellaneous PublicationMP 170Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys10 phttps://doi.org/10.14509/30669paper2021publication dateHendricks, M.D. and others, 2021GIS analysis and digital cartographyU.S. Geological Survey National Cooperative Geologic Mapping Program2020Techniques and MethodsTM 11-B10United StatesU.S. Geological Survey1 phttps://dggs.alaska.gov/pubs/id/30585paper2020publication dateU.S. Geological Survey National Cooperative Geologic Mapping Program, 2020GIS analysis and digital cartographyGeologic 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.2023Data 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.2026vectorNAD83GRS 806378137298.257222101west_susitna_ak_gems_dbGeodatabase, layer files, style files, and fontsDGGSwest_susitna_ak_gems_dbwest_susitna_gems_dbGeodatabase, layer files, style files, and fontsDGGSwest_susitna_gems_dbwest_susitna_gems_geopackageSQLite Database fileDGGSwest_susitna_gems_geopackagewest_susitna_gems_shapefileShapefiles and open data filesDGGSwest_susitna_gems_shapefileState of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveysmailing and physical

3354 College Road

FairbanksAK99709-3707USA907-451-5020907-451-5050dggspubs@alaska.gov8 am to 4:30 pm, Monday through Friday, except State holidaysPlease 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.PIR 2026-1The 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.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.see http://dx.doi.org/10.14509/32075geodatabasegeologic maphttp://dx.doi.org/10.14509/32075Free download20260310Simone Montaynemailing and physical

3354 College Road

FairbanksAK99709-3707USA907-451-5020FGDC Content Standard for Digital Geospatial MetadataFGDC-STD-001-1998If 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.http://www.dggs.alaska.gov/metadata/dggs.extdggs metadata extensions