National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science El Malpais National Monument Geologic Resources Inventory Report Natural Resource Report NPS/NRSS/GRD/NRR—2012/578 ON THE COVER The 3,900-year-old McCartys flow is juxtaposed against the 160-million-year-old Zuni Sandstone, which is capped by 100-million-year-old Dakota Sandstone at the Sandstone Bluffs Overlook. The bluffs consist of gently dipping sandstone that crops out along the eastern flank of the Cebollita Mesa on the eastern margin of El Malpais National Monument. Photograph by Katie KellerLynn (Colorado State University). THIS PAGE The McCartys flow is the youngest lava flow in New Mexico and still exhibits a glassy rind in many locations. Photograph by Katie KellerLynn (Colorado State University). El Malpais National Monument Geologic Resources Inventory Report Natural Resource Report NPS/NRSS/GRD/NRR—2012/578 National Park Service Geologic Resources Division PO Box 25287 Denver, CO 80225 September 2012 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 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/). Please cite this publication as: KellerLynn, K. 2012. El Malpais National Monument: geologic resources inventory report. Natural Resource Report NPS/NRSS/GRD/NRR—2012/578. National Park Service, Fort Collins, Colorado. NPS 103/117008, September 2012 ii NPS Geologic Resources Division Contents List of Figures ................................................................................................................ iv List of Tables ................................................................................................................. iv Executive Summary ....................................................................................................... v Acknowledgements ..................................................................................................... vii Credits ....................................................................................................................................................................... vii Introduction ................................................................................................................... 1 Geologic Resources Inventory Program ......................................................................................................................... 1 Regional Geologic Setting ............................................................................................................................................ 1 Geologic Issues .............................................................................................................. 9 Cave Management ...................................................................................................................................................... 9 Mass Wasting ............................................................................................................................................................ 11 Erosion ...................................................................................................................................................................... 12 Flooding .................................................................................................................................................................... 14 Disturbed Lands ......................................................................................................................................................... 14 Recent and Potential Volcanism ................................................................................................................................. 16 Seismic Activity .......................................................................................................................................................... 17 Geochronology, Future Research, and Interpretation .................................................................................................. 17 Geologic Features and Processes ................................................................................ 19 Volcanic Features and Processes ................................................................................................................................. 19 Vents ......................................................................................................................................................................... 20 Lava Flows ................................................................................................................................................................. 22 Lava Tubes ................................................................................................................................................................. 26 Ice Caves ................................................................................................................................................................... 29 Eolian Features and Processes .................................................................................................................................... 30 Biologic and Geologic Connections ............................................................................................................................ 30 Paleontological Resources .......................................................................................................................................... 32 Sandstone Features .................................................................................................................................................... 34 Geologic History .......................................................................................................... 37 Precambrian Crystalline Rocks .................................................................................................................................... 37 Sedimentary Rocks ..................................................................................................................................................... 37 Volcanic Rocks ........................................................................................................................................................... 41 Unconsolidated Deposits ............................................................................................................................................ 42 Geologic Map Data ...................................................................................................... 43 Geologic Maps .......................................................................................................................................................... 43 Source Maps .............................................................................................................................................................. 43 Geologic GIS Data ..................................................................................................................................................... 43 Geologic Map Overview Graphic ................................................................................................................................ 44 Map Unit Properties Table .......................................................................................................................................... 44 Use Constraints .......................................................................................................................................................... 44 Glossary ........................................................................................................................ 45 Literature Cited