Isostatic depression

Isostatic depression is the downward movement of Earth’s crust under an added load, such as a thick ice sheet, as the underlying mantle is displaced.

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Isostasy: The gravitational balance between Earth’s lithosphere and the underlying mantle, which allows the lithosphere to rise or sink under changing loads. Isostatic depression is the downward response within this broader buoyancy balance.
Fennoscandian Shield: The exposed ancient continental crust of northern Europe, much of it shaped by Pleistocene glaciation. The former Fennoscandian ice sheet depressed this region, which is still rising.
Global Positioning System: A satellite-based navigation system that can measure precise positions on Earth’s surface. GPS records the slow vertical and horizontal motions caused by continuing postglacial adjustment.
Tectonic subsidence: Downward movement of Earth’s surface caused by deformation of the crust or lithosphere through tectonic processes. It lowers land through tectonic forces rather than chiefly through added surface load.
Lithosphere: Earth’s rigid outer shell, comprising the crust and the uppermost mantle. Its downward flexure or sinking is the visible expression of depression.
Hudson Bay: A large inland sea in northeastern Canada, bordered by regions once covered by the Laurentide Ice Sheet. The basin and surrounding land record the immense load of the former ice sheet.
Geodesy: The science of measuring Earth’s shape, gravity field, and changing positions on its surface. Geodetic observations quantify crustal displacement from isostatic loading and unloading.
Compaction (geology): The reduction in volume of sediment or rock as grains pack more closely under pressure. Compaction can cause subsidence within sedimentary layers, unlike mantle-displacement-driven depression.
Asthenosphere: The weak, slowly deforming upper-mantle layer beneath the lithosphere. Its long-term flow permits the lithosphere to subside beneath sustained loads.
Laurentide Ice Sheet: A vast Pleistocene ice sheet that covered much of Canada and parts of the northern United States. Its weight depressed the crust across a broad area of North America.