1. 29 September 2009WAIS/Pack Forest Conference Center Variation in Subglacial Roughness in West Antarctica: How do we interpret causality in the context of sediments? Young, D. A., D.D. Blankenship, S.D. Kempf, J.B. DeSantos, M. Williams, and J. W. Holt

2. 29 September 2009WAIS/Pack Forest Conference Center AIry isostatic deglaciated coastline [Holt et al., 2006]

3. 29 September 2009WAIS/Pack Forest Conference Center 50x vertical Thwaites Glacier Grounding line MacAyeal Ice Stream (Ice Stream E) Grounding line

4. 29 September 2009WAIS/Pack Forest Conference Center Is it the smoothness (symptomatic of smaller scales) that allows rapid basal motion; or is it the rapid basal motion that has smoothed the topography?

5. 29 September 2009WAIS/Pack Forest Conference Center Basal shear stress inversion [Joughin et al., 2009; 2004]

6. 29 September 2009WAIS/Pack Forest Conference Center

7. 29 September 2009WAIS/Pack Forest Conference Center Density variations not due to topography or crustal thickness Lower values imply sediment Isostatic anomaly [Diehl et al., ISASE X 2007] Airborne gravity data

8. 29 September 2009WAIS/Pack Forest Conference Center Anomaly of residual intensity [Holt et al., ISASE X 2007] Lower values imply sediment cover (or sedimentary basement) Airborne magnetic data

9. 29 September 2009WAIS/Pack Forest Conference Center Estimating RMS slope: detrend

10. 29 September 2009WAIS/Pack Forest Conference Center Estimating RMS slope: calculate slope and bin

11. 29 September 2009WAIS/Pack Forest Conference Center

12. 29 September 2009WAIS/Pack Forest Conference Center Across trackAlong track (with focusing) Peters et al. 2007 IEEE 60 MHz beam pattern

13. 29 September 2009WAIS/Pack Forest Conference Center Second Across track Null

14. 29 September 2009WAIS/Pack Forest Conference Center King et al, 2009 result for Rutford

15. 29 September 2009WAIS/Pack Forest Conference Center Rignot et al, 2005

16. 29 September 2009WAIS/Pack Forest Conference Center Anisotropic observations - implies topographic features Rignot et al, 2005

17. 29 September 2009WAIS/Pack Forest Conference Center Basal shear stress Joughin et al, 2009

18. 29 September 2009WAIS/Pack Forest Conference Center 2000 meter deviation

19. 29 September 2009WAIS/Pack Forest Conference Center 40 meter deviation

20. 29 September 2009WAIS/Pack Forest Conference Center Conclusions Low driving stress regions of Thwaites Glacier, MacAyeal Ice Stream and Kamb Ice Stream are underlain by topographic lineations largely confined to the smooth material Low driving stress regions in the WAIS correlate with smooth (at 10’s-100‘s m) material This is consistent with a deforming reservoir of till; of which Thwaites Glacier is lacking. Thanks to G. Unger Vetlesen Foundation the University of Texas at Austin Jackson School of Geoscience, NASA, and the National Science Foundation (OPP projects 0230197, 9319379,0086316, 9911617, 9120464, 9319369)

21. ICECAP 29 September 2009WAIS/Pack Forest Conference Center Budd Basin WAIS/Pack Forest Conference Center

22. ICECAP 29 September 2009WAIS/Pack Forest Conference Center