Tales of the Coast
Coastal Dynamics


Ice and Alaska's Coasts

Coastal ice occurs in Alaska as both tidewater glaciers and sea ice. Tidewater glaciers reach from the Arctic to the non-polar, southern regions of Alaska. As glaciers grow and advance, they change coastal topography by moving over the land and grinding it down.

Conversely, as glaciers melt and retreat, they can leave a formerly frozen shore exposed to wave action, and the meltwater from the glaciers deposits significant amounts of sediment at the coast to form outwash fans and deltas. In these ways, glaciers can erode coastal regions or supply sediment, depending on their movement.

Since the end of the last ice age, Alaska has also been experiencing isostatic rebound as the land rises after the weight of the ice sheets was removed. Along many parts of the Alaskan coast the sea level is dropping because of this process, and it is possible that dredging will have to increase at coastal ports and harbors because of the rising land.

Sea ice forms seasonally, particularly along the northern deltaic coast of Alaska. Wind blows ridges of sea ice onto the shore, which can remove sediment from the beach. When the ice melts, the sediment can move alongshore but it can also be lost to deep water. It is believed that this process erodes Alaska's northern shore.

Glaciated coast
Source: National Oceanic & Atmospheric Adminstration (NOAA)

Ice and Alaska's Coasts

Alaskan Glaciers: Glaciers affected Alaska's shores in the past by creating fjords and depositional features. They continue to impact the shore today by eroding and depositing sediment.