Navajo National Monument Geologic Resource Evaluation Report
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National Park Service U.S. Department of the Interior Natural Resource Program Center Navajo National Monument Geologic Resource Evaluation Report Natural Resource Report NPS/NRPC/GRD/NRR—2007/005 THIS PAGE: The Navajo Sandstone forms steep cliffs above its contact with the Kayenta Formation in Long Canyon and throughout Navajo NM, AZ. ON THE COVER: Photo of the Betatakin Ruins in Navajo NM, AZ . USGS Photos Navajo National Monument Geologic Resource Evaluation Report Natural Resource Report NPS/NRPC/GRD/NRR—2007/005 Geologic Resources Division Natural Resource Program Center P.O. Box 25287 Denver, Colorado 80225 June 2007 U.S. Department of the Interior Washington, D.C. The Natural Resource Publication series addresses natural resource topics that are of interest and applicability to a broad readership in the National Park Service and to others in the management of natural resources, including the scientific community, the public, and the NPS conservation and environmental constituencies. Manuscripts are peer- reviewed to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and is designed and published in a professional manner. Natural Resource Reports are the designated medium for disseminating 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. Examples of the diverse array of reports published in this series include vital signs monitoring plans; "how to" resource management papers; proceedings of resource management workshops or conferences; annual reports of resource programs or divisions of the Natural Resource Program Center; resource action plans; fact sheets; and regularly- published newsletters. Views and conclusions in this report are those of the authors and do not necessarily reflect policies of the National Park Service. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the National Park Service. Printed copies of reports in these series may be produced in a limited quantity and they are only available as long as the supply lasts. This report is also available from the Geologic Resource Evaluation Program website (http://www2.nature.nps.gov/geology/inventory/ gre_publications) on the internet, or by sending a request to the address on the back cover. Please cite this publication as: Graham, J. 2007. Navajo National Monument Geologic Resource Evaluation Report. Natural Resource Report NPS/NRPC/GRD/NRR—2007/005. National Park Service, Denver, Colorado. NPS D- 53, June 2007 Table of Contents List of Figures .............................................................................................................. iv Executive Summary ...................................................................................................... 1 Introduction ................................................................................................................... 2 Purpose of the Geologic Resource Evaluation Program ............................................................................................2 Regional Location and Geology..................................................................................................................................2 Park History................................................................................................................................................................3 Geologic Issues............................................................................................................. 9 Rockfall Hazards ........................................................................................................................................................9 Flash Flooding, Floodplain Degradation, and Erosion................................................................................................9 Hydrogeology ...........................................................................................................................................................10 Regolith ....................................................................................................................................................................10 Geologic Features and Processes............................................................................. 13 Alcoves.....................................................................................................................................................................13 Navajo Sandstone ....................................................................................................................................................13 Betatakin Unit and Visitor Center..............................................................................................................................13 Keet Seel Unit...........................................................................................................................................................14 Inscription House Unit ..............................................................................................................................................14 Map Unit Properties .................................................................................................... 18 Map Unit Properties Table........................................................................................................................................19 Geologic History.......................................................................................................... 21 Triassic Period..........................................................................................................................................................21 Jurassic Period.........................................................................................................................................................22 Cretaceous Period....................................................................................................................................................23 Late Cretaceous-Early Tertiary.................................................................................................................................24 Tertiary Period..........................................................................................................................................................24 Quaternary Period ....................................................................................................................................................24 Glossary....................................................................................................................... 28 References................................................................................................................... 30 Appendix A: Geologic Map Graphic .......................................................................... 33 Appendix B: Scoping Summary................................................................................. 35 Attachment 1: Geologic Resource Evaluation Products CD NAVA Geologic Resource Evaluation Report iii List of Figures Figure 1a: Location map of Navajo National Monument. ...............................................................................................4 Figure 1b: Detailed location map of Navajo National Monument....................................................................................5 Figure 2. Regional physiographic features associated with Navajo National Monument. ..............................................6 Figure 3: Geologic time scale.........................................................................................................................................7 Figure 4. Keet Seel ruins................................................................................................................................................8 Figure 5. Joints along the Aspen Forest Trail...............................................................................................................11 Figure 6. Erosion in front of Keet Seel .........................................................................................................................12 Figure 7. Betatakin ruins in an alcove formed in the Navajo Sandstone ......................................................................15 Figure 8. Keet Seel ruins..............................................................................................................................................16 Figure 9. Inscription House. .........................................................................................................................................17 Figure 10. Late Triassic paleogeography .....................................................................................................................25 Figure 11. Early Jurassic paleogeography ...................................................................................................................26 Figure 12. Cretaceous paleogeographic map ..............................................................................................................27 iv NPS Geologic Resources Division Executive Summary This report has been developed to accompany the digital geologic map produced by Geologic Resource