1. Sediments, Water, and Inland Ice Flow: A Geologic Control on Ice Stream Tributaries? Leo E. Peters Sridhar Anandakrishnan, Richard B. Alley, J. Paul Winberry, Donald E. Voigt, Andrew M. Smith, Donald D. Blankenship, David L. Morse WAIS Conference Friday, September 30, 2005

2. Outline  Importance of Subglacial Sediments  Previous Work along the Siple Coast Along the Ice Streams Along the Ice Streams Onset of Kamb and Bindschadler Onset of Kamb and Bindschadler  Seismic Reflection and Results  Interpretation/Conclusions

3. Subglacial Sediments and Streaming Ice Flow Sediments ? ? ? Paleoshoreline

4. Siple Coast “Ground-Truthing” Seismic Reflection/Refraction Seismic Reflection - Shown C1B DT/DL CT Bindschadler Kamb Whillans

5. C1B Bindschadler Kamb Whillans

6. Peters et al. (accepted by JGR-Solid Earth) Sediments Above and Below the Onset Direction of Ice Flow

7. The C1B Reflection Seismic Profile Direction of Ice Flow

8. The C1B Reflection Seismic Profile Direction of Ice Flow Base of Ice Sedimentary Structure Base of Sediments Basement

9. DT/DL Bindschadler Kamb Whillans

10. Peters et al. (accepted by JGR-Solid Earth) Sediments Above the Onset

11. The DL Reflection Seismic Profile Direction of Ice Flow Depth Below Surface (meters)

12. Reflectivity of the Bed

13. Direction of Ice Flow Depth Below Surface (meters) The DL Reflection Seismic Profile No Amplitude Phase Change = Till

14. Direction of Ice Flow Depth Below Surface (meters) The DL Reflection Seismic Profile Amplitude Phase Change = Dilatant Till

15. Blue = Dilatant Till Red = Till Direction of Ice Flow Depth Below Surface (meters) The DL Reflection Seismic Profile

16. CT Bindschadler Kamb Whillans

17. The CT Reflection Seismic Profile

19. Blue = Dilatant Till to Water Red = Till

20. The CT Reflection Seismic Profile Blue = Dilatant Till to Water Red = Till

21. Siple Coast Ice Dynamics ? ? ? ? Variability across the Siple Coast Pine Island Glacier: faster flow… Different geologic conditions???

22. The Take-Home Message: Ice streaming favors continuous sediment cover and subglacial water. Ice streaming favors continuous sediment cover and subglacial water. Subglacial Geology Matters in Ice Flow Sediment pockets and pooled water may allow for tributary flow. Sediment pockets and pooled water may allow for tributary flow. Possible further inland drainage of the WAIS??? Possible further inland drainage of the WAIS??? No continuity to produce and maintain streaming flow No continuity to produce and maintain streaming flow Subglacial Controls on Pine Island Glacier Ice Flow and Drainage???

23. A Special Thanks to the 2002 – 2003 OND Field Crew And…

24. The Take-Home Message: Ice streaming favors continuous sediment cover and subglacial water. Ice streaming favors continuous sediment cover and subglacial water. Subglacial Geology Matters in Ice Flow Sediment pockets and pooled water may allow for tributary flow. Sediment pockets and pooled water may allow for tributary flow. Possible further inland drainage of the WAIS??? Possible further inland drainage of the WAIS??? No continuity to produce and maintain streaming flow No continuity to produce and maintain streaming flow Subglacial Controls on Pine Island Glacier Ice Flow and Drainage???