THE ROLE OF LATERAL DRAG IN THE DYNAMICS OF ICE-STREAM-B, ANTARCTICA

The Partitioning of resistive force between the bed and sides of Ice S tream B, Antarctica, is obtained for three large areas that have been measured using repeat aerial photogrammetry. Problems associated with data errors and local variations in ice strength and velocity are redu ced by considering the areally averaged budget of forces for each phot o block. Results indicate that the bed under Ice Stream B must be very weak and unable to provide much resistance. Mechanical control on thi s ice stream emanates almost entirely from the lateral margins.