National Park Service U.S. Department of the Interior Natural Resource Program Center Fredericksburg and Spotsylvania County Battlefields Memorial National Military Park Geologic Resources Inventory Report Natural Resource Report NPS/NRPC/GRD/NRR—2010/229 THIS PAGE: Stone wall along the modern day loca- tion of the Sunken Road, one of the bloodiest sites during the Civil War. Of the 12,600 Federal soldiers killed, wounded, or missing during the Battle of Fredericksburg, almost two-thirds fell in front of the stone wall. ON THE COVER: Cannons at Fairview, an important loca- tion during the Battle of Chancellorsville, May 2-3 1863. National Park Service photographs Courtesy Gregg Kneipp (Fredericksburg and Spotsylvania County Memorial Bat- tlefields National Military Park) Fredericksburg and Spotsylvania County Battlefields Memorial National Military Park Geologic Resources Inventory Report Natural Resource Report NPS/NRPC/GRD/NRR—2010/229 Geologic Resources Division Natural Resource Program Center P.O. Box 25287 Denver, Colorado 80225 August 2010 U.S. Department of the Interior National Park Service Natural Resource Program Center Ft. Collins, 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. 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NPS 326/105337, August 2010 ii NPS Geologic Resources Division Contents List of Figures ................................................................................................................ iv Executive Summary ....................................................................................................... v Acknowledgements and Credits .................................................................................. vi Introduction ................................................................................................................... 1 Purpose of the Geologic Resources Inventory ............................................................................................................... 1 History of Fredericksburg and Spotsylvania County Battlefields Memorial National Military Park..................................... 1 Geologic Setting .......................................................................................................................................................... 1 Geologic Issues .............................................................................................................. 7 Introduction ................................................................................................................................................................. 7 Abandoned Mineral Lands ........................................................................................................................................... 7 Channel Morphology ................................................................................................................................................... 8 Siting of Future Facilities .............................................................................................................................................. 8 Hydrogeology .............................................................................................................................................................. 8 Slope Processes and Erosion ......................................................................................................................................... 9 Urban Encroachment ................................................................................................................................................... 9 Surface Water and Sediment Loading ......................................................................................................................... 10 Connections between Geology and the Civil War History ............................................................................................ 10 Potential Fossil Resources ........................................................................................................................................... 11 Geologic Features and Processes ................................................................................ 15 Geology and History Connections ............................................................................................................................... 15 Mineral Resources ...................................................................................................................................................... 15 Faults and Folds ......................................................................................................................................................... 16 Map Unit Properties .................................................................................................... 19 Fredericksburg and Spotsylvania County Battlefields Memorial National Military Park Map Units.................................. 19 Geologic History .......................................................................................................... 29 Precambrian (prior to 542 million years ago) ............................................................................................................... 29 Paleozoic Era (542 to 251 million years ago) ............................................................................................................... 29 Mesozoic Era (251 to 65.5 million years ago) .............................................................................................................. 30 Cenozoic Era (the past 65.5 million years) ................................................................................................................... 31 Glossary ........................................................................................................................ 37 Literature Cited ............................................................................................................ 41 Additional References ................................................................................................. 43 Appendix A: Overview of Digital Geologic Data ....................................................... 45 Appendix B: Scoping Meeting Participants ................................................................ 47 Attachment: Geologic Resources Inventory Products CD FRSP Geologic Resources Inventory Report iii List of Figures Figure 1. Map of Fredericksburg and Spotsylvania County Memorial Battlefields National Military Park ............................. 3 Figure 2. Physiographic map of Virginia ........................................................................................................................... 4 Figure 3. Geologic map of the Piedmont and Blue Ridge in central Virginia ...................................................................... 5 Figure 4. Union army pontoon bridges across the Rappahannock River ........................................................................... 11 Figure 5. Confederate earthworks along visitor trail at the Chancellorsville unit .............................................................. 12 Figure 6. Terraces and River ........................................................................................................................................... 12 Figure 7. Urban development ........................................................................................................................................ 13 Figure 8. Battle Topography ..........................................................................................................................................