Bedrock Adjustment

As we have seen in the previous chapters an ice sheet can easily become a few kilometers thick. For example, the ice thickness on Antarctica reaches values of more than 4500 m with a mean value of about 2000 m. So a considerable pressure is exerted on the underlying bedrock, which will deflect to restore the equilibrium of forces. In some ice—sheet models the effect of ice thickness on bedrock topography is incorporated by assuming local,isostatic adjustment (with a time lag of 4000 years, say).However, the rigidity of the lithosphere gives rise to deviations from isostatic equilibrium, especially near the edges of the sheet.