Tales of the Coast
Coastal Dynamics


Ice and the Great Lakes

Sea ice, which forms seasonally when a body of water freezes, can occur in the Great Lakes as well as in polar ocean regions. Wind blows ridges of sea ice onto the shore, which scours beach sediments. The melting of these ice ridges can cause the sediment to move alongshore, but it can also be lost to deep water. This process results in beach erosion on the shore of the Great Lakes.

The land around the Great Lakes is experiencing isostatic rebound, which is an extremely long-term, gradual process of uplift as the land that was depressed under the enormous weight of the glaciers rises now that the pressure of the ice sheets has been removed. This process is most significant in the northern part of the basin where the glaciers were thickest and slowest to melt. Indeed, in some northern areas the crust has risen more than 21 inches per century. The slow tilting of the basin to the southwest will change the level of water, resulting in eventual inundation of the southern portion.

Source: National Oceanic & Atmospheric Adminstration (NOAA)

Ice and the Great Lakes

Sea Ice: Although termed "sea ice," these sheets form on the Great Lakes when the lakes' surfaces freeze in winter.