maankohoamis

Maankohoaminen is a geophysical process in which the land rises relative to the sea as a response to the removal of the large ice sheets that covered a region during the last glacial period. It is part of isostatic adjustment: after the ice weight is removed, the crust and upper mantle slowly rebound and deform, causing a gradual uplift of coastal areas and land previously burdened by ice.

The driving mechanism is the viscosity-driven flow of the mantle beneath the crust, which allows the lithosphere to rebound toward its original shape. The rate and pattern of uplift depend on past ice thickness, crustal structure, mantle properties, and local topography. As the system relaxes, uplift rates typically slow over time and vary greatly from place to place.

Regions with notable maankohoaminen include Fennoscandia (Finland, Sweden, Norway) and parts of North America such as the Hudson Bay region, as well as other formerly glaciated areas. Measurements use tide gauges, GPS networks, and other geodetic methods to record vertical land motion and relative sea-level change. Coasts may continue to emerge, altering shorelines, harbor depths, drainage patterns, and land use. In the relative sea level record, uplift can offset or even exceed sea-level rise caused by climate factors, complicating long-term coastal planning.

In Finnish, the term maankohoaminen specifically denotes this postglacial land uplift phenomenon. The concept is central to understanding long-term coastal evolution in northern latitudes and other previously glaciated regions. See also postglacial rebound and isostasy.