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.