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Geologic Resources Inventory Report, Fort National Park Service U.S. Department of the Interior Natural Resource Program Center Fort Laramie National Historic Site Geologic Resources Inventory Report Natural Resource Report NPS/NRPC/GRD/NRR—2009/161 ON THE COVER: THIS PAGE: View of Fort Laramie National Historic Site, The Laramie River was a part of life at Fort Lara- looking north across the Laramie River from its mie. Here officers’ children ride along the river, confluence with Deer Creek. Note how the c.1888. View is to the north. fort is situated on a river terrace. NPS image, Louis Brechemin Collection. Courtesy NPS image courtesy Baird Todd (NPS FOLA). Baird Todd (NPS FOLA). Fort Laramie National Historic Site Geologic Resources Inventory Report Natural Resource Report NPS/NRPC/GRD/NRR—2009/161 Geologic Resources Division Natural Resource Program Center P.O. Box 25287 Denver, Colorado 80225 December 2009 U.S. Department of the Interior National Park Service Natural Resource Program Center Denver, Colorado The National Park Service, Natural Resource Program Center 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 are those of the author(s) and 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 National Park Service. 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: Graham, J. 2009. Fort Laramie National Historic Site Geologic Resources Inventory Report. Natural Resource Report NPS/NRPC/GRD/NRR—2009/161. National Park Service, Denver, Colorado. NPS 375/100621, December 2009 ii Contents Figures .......................................................................................................................... iv Tables ............................................................................................................................ iv Executive Summary ...................................................................................................... v Introduction ................................................................................................................... 1 Purpose of the Geologic Resources Inventory ........................................................................................................... 1 Regional Information .................................................................................................................................................. 1 Geologic Setting ......................................................................................................................................................... 1 Park History ................................................................................................................................................................ 2 Geologic Issues ............................................................................................................. 5 Erosion ....................................................................................................................................................................... 5 Surficial Geologic Maps .............................................................................................................................................. 5 Mining and Reclamation ............................................................................................................................................. 5 Seismic (Earthquake) Hazards ................................................................................................................................... 6 Potential External Issues ............................................................................................................................................ 6 Geologic Features and Processes ............................................................................. 14 Geomorphic Features ............................................................................................................................................... 14 Regional Stratigraphic Features ............................................................................................................................... 15 Fossils ...................................................................................................................................................................... 16 Structural Features ................................................................................................................................................... 16 Map Unit Properties .................................................................................................... 20 Geologic History.......................................................................................................... 23 Precambrian (4,600 to 542.0 million years ago) ....................................................................................................... 23 Paleozoic Era (542.0 to 251.1 million years ago) ..................................................................................................... 23 Mesozoic Era (251.0 to 65.5 million years ago) ........................................................................................................ 24 Cenozoic Era (65.5 million years ago to present) ..................................................................................................... 24 Glossary ....................................................................................................................... 34 References ................................................................................................................... 37 Appendix A: Geologic Map Graphic .......................................................................... 39 Appendix B: Scoping Summary ................................................................................. 41 Attachment 1: Geologic Resources Inventory Products CD FOLA Geologic Resources Inventory Report iii Figures Figure 1. Location of Fort Laramie National Historic Site, Wyoming ............................................................................. vi Figure 2. Northern segment of the High Plains surface .................................................................................................. 3 Figure 3. Regional stratigraphic column for the Fort Laramie National Historic Site ...................................................... 4 Figure 4. Fort Laramie, 1850 .......................................................................................................................................... 9 Figure 5. Past and present meandering pattern of the Laramie River at Fort Laramie National Historic Site ................ 9 Figure 6. Aerial image of the western portion of Fort Laramie National Historic Site ................................................... 10 Figure 7. Wyoming coal fields underlie approximately 54% of the state ...................................................................... 12 Figure 8. Sand and gravel (aggregate) deposits in Wyoming ...................................................................................... 12 Figure 9. The main shaft of the Sunrise Mine in 1907 .................................................................................................. 13 Figure 10. The Laramie River as seen from Fort Laramie National Historic Site.......................................................... 17 Figure 11. Relief map of southeastern Wyoming ......................................................................................................... 17 Figure 12. Pipy concretions in the Arikaree Formation ................................................................................................. 18 Figure 13. The corkscrew burrow, Daemonelix, at Agate Fossil Beds National Monument, Nebraska ........................ 18 Figure 14. Schematic illustrations of normal and reverse faulting ................................................................................ 19 Figure 15. Geologic timescale .....................................................................................................................................
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