Back in May I visited Pictured Rocks National Lakeshore between Munising and Grand Marais, Michigan. On that trip my friend and I headed up to Isle Royale National Park for four days of backpacking, and Pictured Rocks was just a brief stop on our way there.
Last week my wife and I revisited this shoreline on our way back from two days at Voyageurs National Park, and we had a little more time to explore it. We did, however, have a large rainstorm bearing down on us from the west, so we had no time to waste.
Our first stop was at Miners Castle, which I visited in May. This spot is too good to miss, and very accessible. In my opinion it should be the first stop for any visit:
These exposed sediments were deposited intermittently from about 800 million to 480 million years ago, from the late Precambrian through the early Ordovician Period. During that time this area was situated near the equator, bordering a shallow sea. Erosion worked away at nearby mountains, and streams carried sand and gravel to the ocean here. The different rock beds are the result of shifting depositional environments over time. Dunes, shores, riverbeds, deltas, and stream channels are all preserved in the rocks. Each environment deposited different sediments containing different minerals, leading to the multi-colored bedding.
Over time these beds were subsequently buried by younger sediment, only to be exposed again by uplift and erosion. In the last few hundred thousand years, repeated glaciation sculpted the surface here. As the glaciers retreated and melted, they left behind crystal-clear Lake Superior and its shores. Over the last 10,000 years the lake’s wave action carved these colorful cliffs from the sandstone.
Unlike my last trip, from here we had time to head down to Miners Beach:
The early dawn light made for some nice contrasting views looking west then east:
We then headed east for a while, skipping past the Chapel Rock area I had hiked in May. We also skipped over Beaver Basin before we finally stopped again near the east end of Twelvemile Beach:
Here many of these cool yellow flowers were growing up along the fences:
Our next stop was at the Log Slide Overlook near the west end of Grand Sable Dunes. During the local white pine logging boom in the late nineteenth century, loggers used this bluff as a slide to send timber down to the lake shore to be loaded onto ships:
From here we could also see the Au Sable Lighthouse:
The rain started to catch up to us as we passed Grand Sable Lake. By the time we got to the east end of Grand Sable Dunes, it started to drizzle rather steadily. With my wife waiting in the car, I made a quick stop to run down the nearly 200 feet of stairs to Sable Falls. Here the water of Sable Creek has carved through 75 feet of the local Munising and Jacobsville sandstones. Many other similar waterfalls are scattered throughout the park.
I then hurried through the light rain to cover the half mile hike over to the east end of Grand Sable Dunes. Although hiking through sand can be a pain, this spot was cool enough to explore for a bit.
Grand Sable Dunes, like Sleeping Bear Dunes in Michigan’s lower peninsula, are examples of perched dunes. These features occur high above bluffs adjacent to shorelines (as seen above at Log Slide Overlook). Unique events and environments lead to their formation, making them relatively rare in the world.
When this area was buried by glaciers as recently as 12,000 years ago, the weight of the ice compacted the ground here. As the glaciers melted and Lake Superior formed, the water level was relatively high. Winds off of the lake blew beach sand and wore away at the coast, driving the dunes inland.
Free from the weight of thick glacial ice, isostatic rebound caused the land here to rise over time. As the relative lake level dropped, the wind and waves continued to work away at the coast, creating high bluffs along the shore.
Since then the wind has continued to drive the perched dunes above the bluffs farther inland.
By the time we left this last stop the rain started pouring down. We were lucky to have completed this visit before getting drenched.