Johnson’s Shut Ins

Posted July 20, 2013

by Lensyl Urbano

Exploring the natural water works at the Johnson's Shut Ins.

Exploring the natural water works at the Johnson’s Shut Ins.

First off, the Shut Ins are narrower constrictions in the river valley formed when stream flows into an area of harder rock. The hard rock, in this case an old (1.5 billion year old) rhyolite flow, is relatively resistant to erosion, especially the side-to-side erosion that flattens out little flood plains as small rivers meander through the foothills of old mountains like the Ozarks. So the stream only erodes downward through the hard rocks creating a narrow gorge. As they say here: the river’s “Shut In”.

When I told people that I wanted to do a few camping trips this summer, the number one recommendation was the Shut Ins. And I can see why. I took my boys and they had an awesome time.

“It’s like the City Museum. Only real.”
— Overheard at Johnson’s Shut Ins

The Shut Ins are a maze of narrow channels, the old igneous rocks carved smooth by the water and its gravelly bed load over millions of years. A great place for kids to traipse through and explore. I bit like a water-park version of the City Museum in St. Louis.

Rushing water in a shallow channel leads to a deeper pool.

Rushing water in a shallow channel leads to a deeper pool.

Looking down from the cliffs above the Shut Ins, the sets of linear joints in the rocks are quite clear.

Looking down from the cliffs above the Shut Ins, the sets of linear joints in the rocks are quite clear.

The pattern of the channels is largely determined by the jointing in the rocks, because the joints offer easier pathways for water and erosion. There are at least two obvious sets of joints in the rocks, but I would not be surprised if they overlay other patterns given how old the rocks are. As it is, however, the erosion through the joints creates lots of neat little chutes.

Looking along a narrow eroded joint.

Looking along a narrow eroded joint.

Since the Shut Ins are only a couple hours away from St. Louis, they’re a pretty popular tourist attraction.

Population density is high.

Population density is high.

There’s a lot of science that can be done here, however, that would make this a good location for an immersion trip, especially since Elephant Hills State Park (with wonderful spheroidal weathering) is close by. The camping facilities at the Shut Ins State Park are new and quite nice, having been completely rebuilt with some of the $100 million in settlement money from the Ameren power company after the park was flooded by their Taum Sauk reservoir breach in 2005.

The path of the wave from the Taum Sauk reservoir breach created a debris field with huge boulders, and demolished the original Johnson's Shut Ins campground. The Shut Ins themselves are downstream to the right.

The path of the wave from the Taum Sauk reservoir breach created a debris field with huge boulders, and demolished the original Johnson’s Shut Ins campground. The Shut Ins themselves are downstream to the right.

It’s certainly worth the visit.

As the stream exits the Shut Ins it has dredged some excellent swimming pools.

As the stream exits the Shut Ins it has dredged some excellent swimming pools.

Citing this post: Urbano, L., 2013. Johnson's Shut Ins, Retrieved September 23rd, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

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