1. Fast-flow signatures on Kamb Ice Stream Howard Conway, Laurence Gray, Ed King, Felix Ng and Ben Smith Acknowledgements: - National Science Foundation and Raytheon Polar Services. - Maurice Conway, Tony Gades and Neal Lord for help in the field. - Charlies Bentley and Raymond for valuable discussions. Image: from Ian Joughin

2. Ridge AB Ridge BC Ice Stream A X Y X’ Y’ Z Z’ Old UPC Camp * 125m RADARSAT mosaic

3. X-X’ Y-Y’ Z-Z’ 2MHz ground-based radar profiles (Tony Gades and Howard Conway, 1998) - disturbed layer stratigraphy is inherited from upstream

4. Recognition of spatial pattern of wiggle patterns and “flow bands”, defined by troughs and crests of radar-detected layers (Felix )

5. Mass conservation requires: outflux (A z U z ) = influx (A x U x ) + net accumulation

6. overall area ratio of ~4 from X to Z implies ~3.5-fold increase in speed downstream (adjusted for deviation of profile-normals to past flow direction)

7. Results from 50MHz radar profiles (Ben Smith and Neal Lord) buried crevasses Radar-detected layer deposited ~1951 buried crevasses at X-line imply high strain rates in the past, and ice stream speeds > 100m/yr hence, speeds at Z-line > 350 m/yr when the ice stream was active (Ng and Conway, 2004)

8. Laurence: analysis of geometry of flow stripes visible in RADARSAT together with data from bedmap (Lythe + Vaughan) X’ Y’ Z’

10. X’ X Y’ Y 125m RADARSAT mosaic What is the origin of RADARSAT- detected flow stripes? likely connection with ice-flow dynamics but weak correlation with the deep-layer folding pattern What properties is RADARSAT detecting?

11. X’X Flow stripes are weakly correlated with deep internal stratigraphy … much better correlated with near-surface stratigraphy processed radiometry from 125m-RADARSAT mosaic (Laurence) near surface internal layer geometry from 50MHz radar – that shows accumulation variations (Ben) X’X

12. X processed radiometry near surface internal layer geometry (accumulation since 1951) surface slope smoothed surface topography from barometric pressure X’ X

13. Y’ Z’ Y-LINE processed radiometry near surface internal layer geometry (accumulation since 1951) Z-LINE processed radiometry near surface internal layer geometry Y Z

14. Synopsis 1.Analyses of deep-layer folds and flow stripe geometry provide estimates of past flow regimes 2.Still not clear what causes the RADARSAT-detected flow stripes - good correlation with near surface internal layers - not obvious how accumulation variations tie in with the formation of flow stripes X EK processed radiometry