Pictured Rocks: Three Hundred Ninety Million Years Facing Lake Superior

The cliffs along this forty-two mile stretch of Lake Superior shoreline are made of sandstone deposited on the floor of a shallow inland sea roughly five hundred million years ago, when this part of the continent sat near the equator and looked nothing like what you are looking at now. The rock was buried, compressed, and eventually exposed by the glacial erosion that carved the Lake Superior basin over the past two million years. What you see now are the cliff faces that the glaciers scraped clean.

The colors are mineral stains. Copper compounds leaching through fractures in the rock produce the green bands. Iron oxides produce the red and orange. Manganese produces the black. The Anishinaabek named this shoreline for what they saw in it, and what they saw was paint. The word that Europeans translated as "pictured" referred to the images the mineral patterns formed on the cliff face.

The National Lakeshore designated here in nineteen sixty-six was the first national lakeshore established in the United States. It protects the cliffs, the beaches, the inland lakes, the rivers, and the forest interior. The Anishinaabek have known this shoreline for twelve thousand years, since before the lake reached its current shoreline level, when the terrain looked different and the ice was still retreating north.

In winter, the mineral seeps freeze into curtains of ice that hang from the cliff edges. In summer, tour boats run along the cliff face close enough to see the colored bands in detail. The lake has been cutting into those cliffs for twelve thousand years. It will continue.