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Tales of the Coast
America's Coasts

Great Lakes: Lake Superior

Much of the Lake Superior shoreline consists of bedrock bluffs that are highly resistant to erosion. These coastal landforms are found on the western side of the lake, from the US-Canada border to an area near Duluth, Minnesota, and in eastern Wisconsin and the south-central shoreline of the Upper Peninsula of Michigan. Erodible cohesive bluffs occur sporadically along the lake's southern shore. These tall slopes are composed of fine sediments that cannot be re-formed once they have been eroded by waves. The far western corner of the lake contains highly erodible red clay bluffs, but they are confined to a relatively small area of shoreline.

Sandy and coarse beaches are interspersed along the southern shore of Lake Superior. Sandy beaches are most common along sheltered shorelines where lower wind and wave energy has allowed small sand particles to accumulate. Along the open coast of the lake, where relatively high wave energy removes all but the largest rocks and sediments, beaches form with cobbles and boulders instead of sand. Wetlands are a rare type of geomorphology on the Lake Superior coast and only comprise about 10% of the shoreline, mostly in sheltered locations.

Photo of Lake Superior Shoreline

Lake Superior Shoreline. Source: U.S. Army Corps of Engineers

Lake Superior Shorelines

Because of the predominance of bedrock shorelines, the coast of Lake Superior has experienced generally low rates of erosion. The exceptions are the red clay bluffs in the western portion of the lake and small pockets of erosion at beaches and cohesive bluffs.