Coastal Geology at Apostle Islands
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Lake Superior engulfs Apostle Islands National Lakeshore. The national lakeshore includes about 42,000 acres (16,997 ha) of “dry” land, and 27,000 acres (10,927 ha) of submerged land. The national lakeshore was established in 1970 to conserve the significant islands and shoreline, including their geographic, scenic, and scientific values.

Apostle Islands National Lakeshore has a wide diversity of coastal features, such as a barrier spit, sand spits, cuspate forelands, tombolos, numerous beaches, sandstone cliffs, and caves. The sandstones of the Apostle Island archipelago were deposited during the late Precambrian era, about 600 million years ago, and form the basement rock for all the islands. The sandstones were deposited by