Glacial isostatic adjustment

Glacial isostatic adjustment is the broader solid-Earth and sea-level response to growth and retreat of ice sheets.

Infer mantle relaxation from dated relative sea levels and shorelines, geodetic displacements, gravity changes and a reconstructed ice/water load history. The inferred viscosity trades off with ice history, lithospheric thickness, radial structure and transient rheology, so independent constraints and uncertainty propagation are essential.

Flexural isostasy models the lithosphere as an elastic plate that bends over a buoyant substrate. For a sinusoidal deflection of wavenumber $k$, bending contributes a restoring stress proportional to $B{k}^4$, where $B$ is the plate's bending stiffness.

The Laurentide Ice Sheet covered much of northern North America during the last glacial period and left a major postglacial-rebound signal after retreat.

The Fennoscandian Ice Sheet covered northern Europe during the last glacial period and produced ongoing uplift around the Baltic region after retreat.