1. Geophysical Discussion of the Royal Astronomical Society, February 28, 1959, Geophys. J. (in the press). See also Nature, 183, 1575 (1959).
2. Lister, H. (private communication).
3. Bourgoin, J. P., Annales de Géophys., 12, 75 (1956).
4. Nye, J. F., J. Glaciol., 3 (Oct.) (1959).
5. Weertman, J., J. Glaciol., 3, 33 (1957).