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Susquehanna River Basin Erosion Rates Derived from 10 Be in Stream Sediment

Susquehanna River Basin Erosion Rates Derived from 10 Be in Stream Sediment. Joanna M. Reuter Paul R. Bierman, Jennifer Larsen University of Vermont Milan J. Pavich, Allen C. Gellis USGS Robert C. Finkel Lawrence Livermore National Laboratory. Erosion rates on a millennial time scale?

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Susquehanna River Basin Erosion Rates Derived from 10 Be in Stream Sediment

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  1. Susquehanna River Basin Erosion Rates Derived from 10Be in Stream Sediment Joanna M. Reuter Paul R. Bierman, Jennifer Larsen University of Vermont Milan J. Pavich, Allen C. Gellis USGS Robert C. Finkel Lawrence Livermore National Laboratory

  2. Erosion rates on a millennial time scale? • Relationships with: • physiographic province? • slope? • lithology? • Comparison with other erosion rate estimates • 1

  3. Production of 10Be from cosmic ray bombardment of quartz Cosmic Rays O 10Be Quartz

  4. Quartz Depth (meters) Si 26Al O 10Be Production Rate 10Be is a proxy for erosion rate

  5. EXPLANATION USGS gage basins Small basins

  6. EXPLANATION USGS gage basins Small basins

  7. EXPLANATION USGS gage basins Small basins

  8. Sampling Strategy

  9. Appalachian Plateaus

  10. Appalachian Plateaus n = 22 Basin average erosion rate (meters/ million years) n = 2 n = 1 10Be Small basins sandstone 10Be USGS basins Suspended sediment yield USGS basins

  11. Valley & Ridge

  12. Valley & Ridge Basin average erosion rate (meters/ million years) n = 7 n = 17 n = 9 n = 7 10Be Small basins sandstone 10Be Small basins shale 10Be USGS basins Suspended sediment yield USGS basins

  13. Piedmont

  14. Piedmont 320 m/my Basin average erosion rate (meters/ million years) n = 7 n = 12 n = 6 10Be Small basins schist 10Be USGS basins Suspended sediment yield USGS basins

  15. 30 Mean slope of basin (degrees) 20 10 0 Physiographic province summary: small basins Basin average erosion rate (meters/ million years) 10Be Appalachian Plateaus sandstone 10Be Valley & Ridge sandstone 10Be Valley & Ridge shale 10Be Piedmont schist

  16. Does slope matter? Erosion rate (meters/ million years) R2 = 0.72 R2 = 0.51 R2 = 0.37 no correlation

  17. 10Be Erosion of the Appalachians 60 50 Erosion rate (meters/ million years) R2 = 0.54 40 30 20 10 0 Smokies data from Matmon et al., 2003

  18. Conclusions • Erosion rate of unglaciated part of Susquehanna River basin: • 16 m/my, with a range from 4 to 54 m/my • Physiographic province matters. • Slope matters. • Lithology shows no clear relation to erosion rates. • Sediment yields are broadly consistent with 10Be erosion rates, except for some Piedmont basins. • A relationship exists between slope and erosion rate across different regions of the Appalachians.

  19. Acknowledgments • Funding: • USGS • NSF • Sample collection & processing: • Eric Butler • Megan McGee • Luke Reusser

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