Horseshoe Upheaval

Southern Illinois definitley has an unique feature, known as the Horseshoe Upheaval.

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The rocks are about 350 million years old and were once some 3,500 feet below the surface. The tremendous power of the earth forced them upward. These upturned rocks are silca-rich limestone and chert of the Fort Payne Formation.

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The Fort Payne layer is the deep rust-colored layer in the above illustration. A line marks the location of the upheaval. The narrow wedge is sandwiched on both sides by younger rocks. This suggests the fault system went through two episodes of movement in opposite directions. First the rocks south of the fault zone were uplifted, bringing the Fort Payne rock to the surface. Then the southern block dropped back down. A wedge of the Fort Payne rock was sheared off and jammed in place within the fault zone.

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I left my truck in the picture for size comparison.

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Notice how the layered chert is turned almost vertical

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Walking isn’t the easiest at this site.

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Calcite veining occurs in a lot of the rock.

IMG_6019 redAgain, the layering was pushed vertically from its original positioning.

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Mosses, lichens and a few plants grow in the upheaval.

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Buffy and I climbed up the slope and

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into the bowl-like top of the upheaval. Obviously, the area is better seen before the trees leaf out.

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This shows limestone.

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We didn’t circle the whole top area. Walking wasn’t the easiest.

The Horseshow Upheaval is part of the Saline County Fish and Wildlife Area.


12 responses to this post.

  1. I’ll bet this was a favorite place of Native Americans. Chert is very hard and has sharp edges when it flakes. I’m wondering if there aren’t also a lot of orchids growing near there because of the alkalinity.


    • I hadn’t thought about Native Americans. The rock doesn’t look like what I think of when think of chert. I hadn’t thought of orchids. That would be excuses to visit at different times of the growing season.


  2. Very cool, I need to bring my dad down there from Mahomet to see that. He is a retired Science teacher and geologist..:-)


    • It’s a small area about 8-9 miles east of Harrisburg. If you do come down, let me know and I’ll tell you how to find it. There’s no sign at the blacktop.


      • Posted by Doug & ViVi Hughes on September 17, 2014 at 10:06 pm

        Please help my wife and I to find this we searched last weekend never found it.

      • It is a little hard to find. Go south out of Harrisburg and turn left on Whitesville road. Stay on it until come to Horseshoe road. Turn left. There’s a bridge right there. Continue on that road until it T’s . Turn left again. Go 1-2 miles I can’t tell by the map I have. There will be a hunter access on the left with a small parking lot. If you come to the trout pond, you just passed it. You can pull in the hunter access lot and continue on the “road” driving or walk around the corner. You’ll come to a bigger open area, with a informational sign about the upheaval. You can hike up into it. It is hard walking and the rock makes it slippery. If you still don’t find it go on to Saline County conservation area (Glen O. Jones lake) and ask there. Good luck

  3. Posted by Therese on April 22, 2013 at 3:31 pm

    What a great teacher you are! You are definitely a steward of the earth. Thank you for what you do.


  4. Very interesting, I’m always amazed by our Earth’s upheavals and changes. You did a nice job of explaining everything and the photos are a great help! Kathi


  5. Posted by Doug Hughes on September 18, 2014 at 3:43 pm

    Thanks for the info on the directions. We passed it 4 times then, I know just where its at


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