Pictured Rocks Lakeshore

On Tuesday evening July 29th, we took a sunset cruise on Lake Superior to see the Pictured Rocks. It was so beautiful.

The brochure gives the following information about Pictured Rocks: “Massive glaciers inched back and forth across this land for a million years, scouring and molding, while the land yielded and took on a new shape. Moving ice ground the volcanic and sedimentary rock of previous eras into rubble and slowly enlarged river valleys into the wide basins that would become the Great Lakes. The last glacier began its retreat about 10,000 years ago. Overt time meltwater from this wasting glacier formed powerful rivers and scattered rubble onto outwash plain and into crevasses. The water scooped out basins and channels hat harbor the wetlands found in the park today. Eventually, as the weight of the glacier lessened, the land rose and exposed bedrock to lake erosion. It was this onslaught by the lake-centuries of battering waves and ice—that carved the bedrock into young cliffs. Relentlessly the water continues to pound and sculpt the cliffs, eroding them inland while enlarging the lake.

Solid or liquid, the force of the water profoundly altered the landscape an created the largest freshwater lake system in the world. The name “pictured rocks” comes from the streaks of mineral stain that decorate the face of the sculpted cliffs. The Munising Formation makes up much of the angled slope and formations, such as Miner’s Castle. Covering all is the 400 million-year-old Ordovician Au Train Formation, a harder limy sandstone that serves as capstone and protects the underlying sandstone from rapid erosion. The streaks on the cliffs occur when groundwater oozes out of cracks. The dripping water contains iron, manganese, limonite, copper, and other minerals that leave behind a color stain as water trickles down the cliff face.