Fog occurs commonly. The Lake Superior shoreline consists of rugged volcanic bedrock. Copper-rich lava flows were extensively mined. Linear bedrock ridges and narrow wetlands characterize most of the island, while thin, rocky till covers the southwestern end. Streams on the island are small.
Bedrock is at the surface over most of the island.
Depressions in the bedrock contain organic soils. The thin, rocky soils of Isle Royale supported trembling aspen, white spruce, and balsam poplar. Sugar maple grew on areas with deeper soils. Both windthrows and fires noted. Copper was mined by Native Americans and by early European settlers.