National Park Service US Department of the Interior Natural Resource Stewardship and Science Lassen Volcanic National Park Geologic Resources Inventory Report Natural Resource Report NPS/NRSS/GRD/NRR—2014/755 ON THE COVER Bumpass Hell. Bumpass Hell is one of the primary hydrothermal areas within Lassen Volcanic National Park. At sunset (shown on cover) it appears golden, while during the day, the pools look aqua blue (fig. 15). National Park Service photograph, available at http://flic.kr/p/cePV8N (accessed 12 November 2013). THIS PAGE Lassen Peak. Lassen Peak is the southernmost active volcano in the Cascade Range. Before the 1980 eruption of Mount St. Helens in Washington, Lassen Peak was the most recent volcanic outburst in the contiguous 48 states. A series of eruptions occurred between 1914 and 1917, with the most powerful on 22 May 1915. Photography by Benjamin Franklin Loomis, available at http://www.flickr.com/photos/lassennps/8435233161/ (accessed 5 November 2013). Lassen Volcanic National Park Geologic Resources Inventory Report Natural Resource Report NPS/NRSS/GRD/NRR—2014/755 National Park Service Geologic Resources Division PO Box 25287 Denver, CO 80225 January 2014 US 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 high-priority, current natural resource management information with managerial application. The series targets a general, diverse audience, and may contain NPS policy considerations or address sensitive issues of management applicability. 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. Printed copies of this report are produced in a limited quantity and they are only available as long as the supply lasts. This report is available from the Geologic Resources Inventory website (http://www.nature.nps.gov/geology/inventory/ gre_publications.cfm) and the Natural Resource Publications Management website (http://www.nature.nps.gov/publications/nrpm/). To receive this report in a format optimized for screen readers, please email [email protected]. Please cite this publication as: KellerLynn, K. 2014. Lassen Volcanic National Park: geologic resources inventory report. Natural resource report NPS/NRSS/GRD/NRR—2014/755. National Park Service, Fort Collins, Colorado. NPS 111/123450, January 2014 ii NPS Geologic Resources Division Contents List of Figures and Tables ............................................................................................. iv Executive Summary ....................................................................................................... v Acknowledgements and Credits ................................................................................. vii Introduction ................................................................................................................... 1 Geologic Features and Processes .................................................................................. 5 Volcanic Features ......................................................................................................................................................... 5 Geothermal and Hydrothermal Systems...................................................................................................................... 11 Hydrothermal Features ............................................................................................................................................... 13 Glacial Features ......................................................................................................................................................... 16 Lakes ......................................................................................................................................................................... 19 Meadows .................................................................................................................................................................. 20 Streams and Waterfalls .............................................................................................................................................. 21 Geologic Issues ............................................................................................................ 23 Hydrothermal Hazards ............................................................................................................................................... 23 Volcano Hazards ........................................................................................................................................................ 25 Seismic Activity .......................................................................................................................................................... 27 Slope Movements ...................................................................................................................................................... 28 Geothermal Development .......................................................................................................................................... 29 Abandoned Mineral Lands ......................................................................................................................................... 30 Disturbed Lands Restoration ....................................................................................................................................... 30 Manzanita Lake Dam ................................................................................................................................................. 33 Geologic History .......................................................................................................... 35 Regional Volcanism .................................................................................................................................................... 35 Volcanic Centers ........................................................................................................................................................ 35 Glaciations ................................................................................................................................................................. 38 Recent Volcanic Activity ............................................................................................................................................. 39 Present-Day (Non-Volcanic) Geologic Activity ............................................................................................................. 42 Geologic Map Data ...................................................................................................... 43 Geologic Maps .......................................................................................................................................................... 43 Source Maps .............................................................................................................................................................. 43 Geologic GIS Data ..................................................................................................................................................... 43 Map Unit Properties Table .......................................................................................................................................... 44 Geologic Map Graphic ............................................................................................................................................... 44 Use Constraints .......................................................................................................................................................... 44 Glossary ........................................................................................................................ 47 Literature Cited ............................................................................................................ 51 Additional References ................................................................................................. 57 Appendix A: GRI Participants ...................................................................................... 59 Appendix B: Geologic Resource Laws, Regulations, and Policies ............................. 61 Map 1: Simplified Geologic Map...................................................................... in