GLACIAL REBOUND AND SEA-LEVEL CHANGE - AN EXAMPLE OF A RELATIONSHIP BETWEEN MANTLE AND SURFACE PROCESSES

The problem of glacial rebound provides an outstanding example of the relationship between surface and mantle processes on time scales of 10 (3) to 10(5) years. Changes in surface loading of ice and melt-water a ssociated with the growth and decay of the great ice sheets deform the surface of the planet and induces flow in the mantle. A measure of th e Earth's response to the changing surface loads and internal deformat ion is provided by observations of past sea levels relative to the pre sent level, and inversion of these observations provides constraints o n both the models of the rheological response of the Earth to loading and on models of the ice sheets. Constraints on ice sheet models inclu de the total volume of the grounded ice at the time of maximum glaciat ion, the global rates of melting of the ice sheets, the thickness of t he ice at maximum glaciation, the extent of ice cover over shallow sea s such as the North Sea and the Barents Sea, and the role of Antarctic a in the global ice balance. Constraints on mantle parameters include the effective lithospheric thickness and the effective viscosity of th e mantle. Some recent results for both sets of parameters are discusse d.