first_imgOn RADARSAT imagery, the southern margin of the onset zone of Bindschadler Ice Stream,West Antarctica, manifests a multi-banded feature, with brightness varying across the bands andoscillating along each band. Ground-based radar profiles across the margin reveal folds in the firnstratigraphy associated with this pattern and provide evidence for correlation between the depth ofshallow isochrones and the RADARSAT backscatter intensity on each profile, allowing us to interpret thebanded feature for firn-layer geometry in three dimensions. We use a kinematic model of isochronedepth evolution to show how layer folding and the band expression may result from deformation andadvection in the near-surface flow field at ice-stream margins, even with steady flow. The model predictsthe formation of longitudinally patterned bands when the ice-stream acceleration fluctuates along flow.Concerted study of the planform and stratigraphy of other RADARSAT-detected features on the icesheets may help us understand their origin.last_img read more