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Tales of the Coast
Coastal Dynamics

Ice

Ice affects the coast in two forms: as tidewater glaciers and seasonal sea ice. Tidewater glaciers are found on Alaska's coast, often in fjords and embayments. Sea ice also occurs in Alaska as well as the Great Lakes when it forms in the winter. Sea ice rarely forms in the northern Atlantic.

Both forms of coastal ice can erode, transport, or deposit sediment. Although it would seem that ice armors the coast and prevents sediment transport, it is in fact a dynamic agent along coasts that feature large sheets of ice.

The former presence of ice also changes coastal areas in a different way. Land masses that were depressed under the weight of previous glaciers are rebounding, which results in a long-term lowering of sea level along adjacent coasts. In certain areas of formerly glaciated Alaska (for example, Juneau), the land is rising by 1 cm per year, based on tide gauge records. This changes the parts of the coast being exposed to wave and current action.

 

Ice

Post-Glacial Changes: Shoreline position may advance in places where sea level is falling and sediment is deposited.