Surface-wave dispersion for the ice sheet of Marie Byrd Land, Antarctica, in which velocity and density increase continuously with depth and gradients near the surface are steep, has been computed by solving the equations of motion directly by finite differences. No simplifying assumptions or approximations about parameter variations with depth have been made. Computer results agree well with observed data without the introduction of any anisotropy, as was needed in a previous analysis (Acharya, 1972). Tests of the assumptions made in the previous analysis show that (a) the approximation Poisson's ratio = 14 introduces no significant error even though Poisson's ratio actually varies from 14 to 13 in the upper part of the ice sheet, and (b) the assumption of a constant density, required if one is to separate compressional and shear-wave displacement potentials, is unsatisfactory.

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