National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science Bering Land Bridge National Preserve Geologic Resources Inventory Report Natural Resource Report NPS/NRSS/GRD/NRR—2019/2024 ON THE COVER Photograph of a volcanic feature, “tumulus,” that formed in the Lost Jim lava flow (map unit Qlj). This flow is composed of pahoehoe lava, a type of lava characterized by smooth, ropy surfaces. Tumuli are common pahoehoe feature and form by injection of lava beneath an overlying solidified crust, creating a domed structure. The Lost Jim lava flow erupted about 1,605 years ago, making it the youngest of five distinct volcanic formations that together form a plateau around Imuruk Lake. NPS photograph courtesy of David Swanson (NPS Arctic Inventory and Monitoring Network). THIS PAGE Photograph of the granite tors near Serpentine Hot Springs. Tors are exposed mases of rock (usually jointed granite) that rise abruptly from the surrounding landscape. The tors near Serpentine Hot Springs are composed of rock belonging to the Oonatut Granite Complex (map unit Ktg), one of the tin-bearing granitic intrusions that formed on the Seward Peninsula between 80 million and 70 million years ago. National Park service photograph courtesy of Bering Land Bridge National Preserve. Bering Land Bridge National Preserve Geologic Resources Inventory Report Natural Resource Report NPS/NRSS/GRD/NRR—2019/2024 Amanda Lanik Geologist National Park Service Geologic Resources Inventory Alaska Regional Office 240 W. 5th Ave. Anchorage, AK 99501 David K. Swanson Ecologist National Park Service Arctic Inventory and Monitoring Network 4175 Geist Rd Fairbanks, AK 99709 Ronald D. Karpilo Jr. Research Associate National Park Service Geologic Resources Inventory Colorado State University PO Box 25287 Denver, CO 80225 October 2019 U.S. Department of the Interior National Park Service Natural Resource Stewardship and Science Fort Collins, Colorado The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, Colorado, publishes a range of reports that address natural resource topics. These reports are of interest and applicability to a broad audience in the National Park Service and others in natural resource management, including scientists, conservation and environmental constituencies, and the public. The Natural Resource Report Series is used to disseminate comprehensive information and analysis about natural resources and related topics concerning lands managed by the National Park Service. The series supports the advancement of science, informed decision-making, and the achievement of the National Park Service mission. The series also provides a forum for presenting more lengthy results that may not be accepted by publications with page limitations. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. This report received informal peer review by subject-matter experts who were not directly involved in the collection, analysis, or reporting of the data. Views, statements, findings, conclusions, recommendations, and data in this report do not necessarily reflect views and policies of the National Park Service, U.S. Department of the Interior. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the U.S. Government. This report is available from the http://go.nps.gov/gripubs, and the https://www.nps.gov/im/publication-series. htm. If you have difficulty accessing information in this publication, particularly if using assistive technology, please email [email protected] Please cite this publication as: Lanik, A., D. K. Swanson, R.D. Karpilo Jr. 2019. Bering Land Bridge National Preserve: Geologic resources inventory report. Natural Resource Report NPS/NRSS/GRD/NRR—2019/2024. National Park Service, Fort Collins, Colorado. NPS 182/165283, October 2019 ii Contents Executive Summary ................................................................................................................................................ix Products and Acknowledgments ..........................................................................................................................xv GRI Products .................................................................................................................................................................................................xv Acknowledgments .......................................................................................................................................................................................xv Geologic Setting and Significance ..........................................................................................................................1 Park Establishment and History ................................................................................................................................................................... 1 Geologic Setting ............................................................................................................................................................................................ 2 Geologic Significance and Connections ....................................................................................................................................................... 4 Geologic Features and Processes ............................................................................................................................9 Bedrock .......................................................................................................................................................................................................... 9 Volcanism ..................................................................................................................................................................................................... 16 Cave Resources ............................................................................................................................................................................................ 27 Serpentine Hot Springs ............................................................................................................................................................................... 30 Quaternary Surficial Deposits ..................................................................................................................................................................... 32 Permafrost and Thermokarst ..................................................................................................................................................................... 34 Coastal Features .......................................................................................................................................................................................... 36 Paleontological Resources .......................................................................................................................................................................... 40 Geologic History .....................................................................................................................................................43 Terrane Translation and Accretion ............................................................................................................................................................. 43 Late Proterozoic Eon to Devonian Period ................................................................................................................................................. 43 Late Jurassic to Earliest Cretaceous Periods .............................................................................................................................................. 44 Cretaceous Period ....................................................................................................................................................................................... 45 Eocene to Early Oligocene Epochs ............................................................................................................................................................. 46 Late Oligocene to Holocene Epochs .......................................................................................................................................................... 46 Geologic Resource Management Issues ...............................................................................................................47 Geologic Resource Management ............................................................................................................................................................... 47 Geohazards .................................................................................................................................................................................................. 47 Abandoned Mineral Lands Mitigation ...................................................................................................................................................... 52 Oil and Gas Development Potential .........................................................................................................................................................