Form and Color - Pictured Rocks


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Published: June 17th 2018
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The View from Inside Ice Box Cave
Pictured Rocks National Lakeshore, Munising, Michigan

We began our exploration of this park yesterday with a bang - the Sunset Cruise, offered by Pictured Rock Cruises out of Munising, Michigan will be one of the all-time highlights of this trip. We knew this was highly touted as a good way to see this park, but we had no idea just how good it would be. Even though it was overcast the entire trip, the colors in the rocks came through just fine and the thrill of being next to, and in one case, right in them, was an invigorating experience. Yes, there are hikes through this park, but you won’t be able to see the majesty of these bluffs from on top of them - you have to be on the lake itself. (For more rugged types, a multi-day kayak trip along these shores is about the only way I can imagine beating the cruise.)

But let me back up a bit. We got a late start on the day and then had some difficulty locating the visitor center for this park. There is an Interagency Visitor center in Munising itself, near the boat ramp. Its not a bad place to start and includes a lot of NPS material about the Lakeshore, as well as information about the Hiawatha National Forest and the Seney Wildlife Refuge. They have a short film about the lakeshore and the history of this part of the lake.

There are, apparently, three Park Service visitor centers for this lakeshore, although none of them are real big. We finally found the westernmost center at Munising Falls. We talked to the ranger there about how to spend our time and she confirmed what we understood - that the boat cruise was the best way to go. Drawing on a map of the park, she outlined her favorite spots for hikes and picnics and we will be visiting some of them over the next three days. And, of course, I bought a book about the unique geology of Lake Superior and that will be my reading material for the week.

After the visitor center, we took a short hike (maybe half a mile total) to see Munising Falls. This is a fun little waterfall that illustrates the stream erosion occurring all through the park, as flowing water slowly breaks down the layered sedimentary rocks that make up this side of Lake Superior. Still tired from the long drive on Friday, we went back home and took a nap.

Around 6:00 PM we got up and started getting ready for our boat cruise, which boarded at 7:15. It was a good thing I had made advanced reservations as the boat was full - maybe 150 people. The boat was 65 feet long and about 25 feet wide, so it wasn’t exactly tiny. As the captain noted, it was powered by two Cummins Diesel engines and cruised at a top speed of 13 mph. Those facts became relevant later on the trip. The captain deftly maneuvered the boat out of the dock, narrowly missing other boats. But he certainly had a confidence that was reassuring and a narrative about the views that was full of information - and several very corny jokes!. The crew of two were friendly college-age types who were also very ready to answer questions. The weather was a little uncertain, overcast and occasionally spitting raindrops. But it held off for the entire trip, thankfully giving us plenty of opportunities to view the bluffs and take pictures.

First, a couple of facts about Lake Superior from the cruise, the rangers at the visitor center, and some reading I’ve already done. Superior is the largest of the Great Lakes - you can see that on maps. What the maps don’t tell you though, is that Superior is also the deepest of the lakes, plunging more than 1000 feet deep at certain parts of the lake. The result is a massive amount of water. In fact, Superior holds half of all the water in all five of the Great Lakes. If you spread all the water in Superior out across the 48 continental U.S., it would be five-feet deep. Superior, being the northernmost lake, is also the coldest, rarely getting much above 50 degrees even in the summer. At its depths, the temperature is around 40 degrees, plus or minus two. I suppose you can swim in this lake, but it will likely be a short one.

Superior is the cleanest of all five lakes, reflecting the reality of the Northern Woods. The poor soils mean that there is little agricultural fertilizer runoff because there is little agriculture. The lack of industry up here means minimal industrial pollution. Iron ore mining in the Duluth and Copper Harbor area stimulated a lot of shipping activity, as did the harvesting of vast amounts of lumber. But there is little other industry here and that means little lake pollution. So what you have with Lake Superior is one huge body of very fresh water!

Sediments from ancient oceans dating back half a billion years were laid down and formed sandstone layers of different degrees of hardness and thickness. The top layer, being especially compacted, has resisted erosion the most. The softer layers underneath are more susceptible to wind and water effects. After the glaciers carved out these valleys, melted, and created these huge lakes, the rock underneath rebounded and thrust upward creating these bluffs. Over the last 10,000 years, the erosion of these sandstone layers creates the caves, arches, and sculptures that form the substance of Pictured Rocks.

The boat ride last night skirted the twelve miles of these formations, stopping at several points of special interest. The captain had interesting stories to tell about Miner’s Castle, Broken FlowerPot, Lover’s Arch, and so many more formations. At certain points the bluffs rise 200 feet above the lake. The colors all come from minerals in the ground water that seep through the sandstone layers. There are streaks of black (manganese), green (copper), white (calcium), and red/orange/brown (iron) that brighten the rockface.

The climax of the ride came very unexpectedly. We were riding along at a fairly good clip and the captain slowed the boat a bit and mentioned that we were approaching Ice Box Cave, a deep cave carved into the rocks that is shielded so well from the sun that it is covered in ice in the winter with some even remaining right now. Eager to show us the cave, he proceeded right into it, and into it, and into it! As the cave narrowed I kept saying, OK, he’s got to quit now, doesn’t he? But he didn’t. The cave walls soon swallowed the entire boat and, in the end, a crew member standing in the bow reached out and touched the cave wall at the back end of the cave. He gave a slight push and the captain put it in reverse and we backed out. I swear, though, that the clearance on either side of the boat was less than six feet. Certainly got all the passengers to their feet!

After going a bit further on, we finally reached Spray Falls, the end of the rock formations, and the end of the tour. He turned the boat around, and at full throttle, we whizzed past the edges of many of the formations we had just seen from a little bit further out. Apparently, with the lake calm, and those big Diesel engines, the captain felt very confident giving us one last thrill - we could almost touch the edges of the rocks as they flew by.

When at Pictured Rocks, do not miss the boat cruise!


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