Johnson's Shut-ins State Park in Missouri
How Johnson's Shut-ins was formed | Geology of Johnson's Shut-ins
Missouri Geology

Nearly 1.5 billion years ago, violently explosive volcanoes hurled hot gasses and ash into the air. The ashes and gas fell and cooled, forming rhyolite rock. A billion years later, shallow inland seas swallowed the ancient, worn-down mountains, burying the igneous rock under thousands of feet of sedimentary rock such as limestone, sandstone, shale and dolomite.

About 250 million years later, the entire Ozark region lifted and the seas retreated. The wind and rain took their toll on the upraised land, sending streams of sand- and gravel-laden water to slice away the layers of soft sedimentary rock and expose the rhyolite below. In low places, the swift Black River became shut-in by the hard igneous rocks, swirling and churning to form huge potholes, and breaking away the weaker rock to create natural water slides and canyon-like gorges.

This immense natural playground is the primary feature of the 180-acre Johnson’s Shut-Ins Natural Area, only a portion of the 8,549-acre Johnson’s Shut-Ins State Park. Most of the park, including the shut-ins and two miles of river frontage, was donated in 1955 by Joseph Desloge, a St. Louis civic leader and conservationist from a prominent lead-mining family.

A portion of the park is included in the state’s largest natural area, the 7,028-acre St. Francois Mountains Natural Area. Another part, the Johnson’s Shut-Ins Fen Natural Area is a 9-acre combination of seep forest and calcareous fens found in the flood plains of the East Fork Black River. This wetland community is promoted by seasonally ponded rain water and calcareous ground water seepage on the flat flood plain. Seep forests are rare in Missouri and this unique location is dominated by trees such as Red Maple, Green Ash, Honey Locust and Slippery Elm and wetland plants such as Closed Gentian and Silky Willow are found in the fen.

A relatively rare area in the St. Francois Mountains region, the 18-acre Dolomite Glade Natural Area is the only dolomite glade represented from the St. Francois Mountains section of the Ozark Natural Division. Some plants, including Missouri’s Evening Primrose, Sandwort, and Englemann’s Adder’s Tongue Fern are found nowhere else in the park.

There are an abundance of recreational activities in the 1,100-acre East Fork Wild Area in which the major portion of the park’s biological and geological diversity is protected. Many of the over 900 species of plants that have been discovered in the park are located only in the East Fork Wild Area, including several types of rare plants and the largest Virginia Witch Hazel in the state. The wild area has a wide range of natural habitats, from upland ridges, bluffs and wet meadows, to bottomland woods which boast Oak, Hickory, and Shortleaf Pine, trees durable enough to grow in the thin, rocky soil. Like the Johnson’s Shut-Ins Natural Area, the wild area is dotted with several glades, the equivalent of a desert in Missouri. The barren, rocky areas provide open scenic views and support drought-resistant plants such as Flame Flower, Pineweed, and the Prickly Pear Cactus, as well as animals such as scorpions and the rare eastern collared lizard, or “mountain boomer”.

The nearby 4,874-acre Goggins Mountain Wild Area was acquired by the parks division of the Department of Natural Resources in 1993, and was designated as Missouri’s largest state wild area in 1995. The Goggins Mountain Valley contains the Wild Area as well as the Goggins Mountain Hiking and Equestrian Trail which opened in 2000. This valley will become the new home of the campgrounds for Johnson’s Shut-Ins State Park, which were destroyed in the breach of the upper Taum Sauk Hydroelectric Plant Reservoir atop Profitt Mountain on December 14, 2005.

The breach of December 14, 2005

Early that morning, the park was assaulted with over one billion gallons of water rushing from the broken reservoir atop Profitt Mountain, through the campground and shut-ins and down the East Fork of the Black River. This onslaught of water left behind devastation in the form of enormous boulders, several feet of sand and clay and broken and uprooted trees piled up to 15-feet high on the few trees left standing in the 52-site camping area and fen. The campground was destroyed, filled with concrete and rebar from the broken reservoir. Most of the trees and buildings were gone, replaced by boulders and sand that were carried with the water. Amazingly, one building in the campground-a basic vault toilet-was spared from the flood’s force, losing only its rear wall. The fixtures, rolls of toilet paper, and even a flypaper strip were left intact, and this toilet now represents two distinct periods in the park’s history.

Though the destruction seemed overwhelming, restoration soon began. Mangled trees were mulched in a 50-foot-long tub grinder to form piles of mulch as deep as 15 feet. Truckloads upon truckloads of sand and sediment were removed. Once cleared, native grasses and saplings were planted and new local topsoil was brought in to replace what had been washed away. Wetland ecologists and soil biologists were brought in to determine how to restore the precious, delicate fen. The sand and sediment covering this fragile area was several feet deep in places and was mostly removed using a large, industrial vacuum, though the most sensitive areas could withstand the use of only shovels, rakes and wheelbarrows to uncover the buried vegetation. This area had to be cleared by spring, or the buried plants would die. The recovery and reestablishment of the fen was the park’s first major success.

The hard, volcanic rocks that make up the shut-ins were virtually unscathed, though some of its potholes and gorges were filled with boulders, gravel, concrete and rebar, making swimming temporarily unsafe. The boardwalk to the shut-ins was rebuilt, and the park opened for limited day-use in May 2006. Visitors could see the path of destruction and the on-going restoration, but were not allowed to swim, or explore the rocks of the shut-ins. The immense recovery effort continued throughout that summer and winter, and on through the spring of 2007. On July 2, 2007, visitors were again allowed to enjoy the park’s most popular feature, the rocks for which it was named, and the newly restored river that ran over and among them.

This past September, the park closed again to continue restoration and development. The new entrance from Highway N will boast a boulevard road system leading to the new multi-story park Office, Store and Interpretation and Information Center located on a sloping high point with views of both the Scour Channel and park valley. From the boulevard, dispersed parking areas will be available to access the abundance of day-use areas including playgrounds, picnic areas and several different themed trails. There will be areas for fishing and wading along the river, as well as un-programmed, free play spaces. The Ozark Trail will be rerouted through the park and will include a backpack camp.

The Scour Channel is such a unique feature it may rival the shut-ins for the most popular area of the park. There will be access to the boulder field from the park as well as from a separate entrance in Highway N which will provide an overlook of, and access to, the Scour Channel so visitors may enjoy this incomparable aspect of the flood. The campground is being relocated outside of the flood plain to the Goggins Mountain valley, approximately a mile from the park’s main entrance. A shuttle system is expected to be used to circulate visitors from the campground to the Scour Channel Overlook, the park Office and Store and the Shut-Ins.

Johnson’s Shut-Ins State Park has long been one of Missouri’s most popular state parks, entertaining nearly 250,000 visitors a year. For 2008, there will be swimming in the shut-ins from Memorial Day Weekend until Labor Day Weekend and the rest of the park will remain closed for redevelopment. The park is expected to be fully open and operational sometime in 2009, better than ever, providing satisfaction to visitors with an array of interests-from camping and swimming, to hiking, birding and studying the variety of plant life and the exceptional rock formations. For updates on the redevelopment of Johnson's Shut-ins, please see the Department of Natural Resources page on the park's redevlopment.

by Mary Eakins Bullis, November 2007

Directions:  Highway 21 to Highway "N" (Middlebrook, MO)

Published Monday, October 20, 2008 in the Columbia Tribune

LESTERVILLE (AP) - The raging flood from a December 2005 breach in the Taum Sauk reservoir not only ripped trees and soil from the side of Proffit Mountain, it sliced through centuries of time.

The 1.3 billion gallons of water stripped all the dirt in its path, revealing a literal blast from the past: Taum Sauk rhyolite rock created 1.4 billion years old when volcanoes exploded to create the St. Francois Mountains.

The uncovering of the large bed of rhyolite is a silver lining in the tragedy that injured the ranger’s family, destroyed their home and a state campground and permanently changed the face of Johnson’s Shut-ins State Park.

The scour channel also holds rocks from at least three other geological eras as well as a 530-million-year-old beach near the top of the mountain.

"We have 900 million years of the Earth’s history right here," said Cheryl Seeger, geologist for the Missouri Department of Natural Resources.

Scientists use radiometric dating to determine the age of rocks, said Joe Gillman, DNR division director. "That is a technique that is based on naturally occurring radioactive isotopes in the rock," he explained. "We know what the half-life of radioactive isotopes is. We can age-date the rock based on how much of the radioactive isotope has decayed over time."

The discovery has drawn attention from geologists around the world who are hoping to get a close look at the scour channel. The upper half is owned by Ameren. DNR hopes to make its half of the channel available to the public next year.

Safety concerns are one reason the scour channel is off-limits. Parts of the rock-strewn channel are treacherous to walk on.

Another reason is the educational value, especially to geologists. "It’s a major area of interest," Seeger said. "We’re uncovering an ancient mountain range."

It was a cloudy, rainy summer morning when Seeger arrived to escort a reporter and Parks Department employees Rose Pollard, Pamela Kugel-Rolls and Hannah Memhardt on a tour of the scour channel.

The bottom of the channel slopes almost imperceptibly at first, then steadily rises until mid-channel, where the slope sharply steepens. Small rocks lay across the lower stretch, but the rocks grow larger and cover the channel as the trail begins to climb.

"The water came down the steeper slope very fast, and when it hit the flatter valley floor, it immediately began digging out and scouring a big hole," Seeger said. "Then as the water moved past that point, it started slowing just enough that it started dropping a lot of the material that it had been carrying down the hillside."

Wildflowers and other plants now grow throughout the lower third of the channel. Most of the irregularly shaped rocks are baseball size or smaller, and walking is easy.

Around the bend, the channel slopes upward. Here, walking is more difficult among the angular, basketball-sized rocks. Seeger stopped to pick up samples of rock, including rhyolite, dolomite, granite, sandstone and chert. Many of the rocks came from inside the reservoir walls, carried down by the water after it knocked down a 656-foot section of the dam.

Seeger pointed to a series of tiny ridges on a section of harder rock. "These were created by waves from a huge saltwater sea that lapped the shore," she said. "This was a beach about 530 million years ago."

The entire St. Francois Mountain range, once higher than the Rocky Mountains, eventually was covered by sea. That was long before the glaciers melted, fish swam in the sea or dinosaurs roamed the Earth, she explained.

Almost 1.5 billion years ago, "caldera" volcanoes spewed forth hot gases and materials from under the Earth, creating mountains. Eruptions left holes underground, which eventually caused the mountains to collapse. This pattern continued for centuries. Unlike Hawaiian volcanoes that spew liquid lava, calderas erupt explosively. "Think Mount St. Helens, only huge," Seeger said. "If you think of St. Helens’ " eruption "as the size of an espresso cup, Yellowstone was a 50-gallon bag and ours was a 30-gallon bag."

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