4
KARST FEATURES
DECAY is a word with negative connotations when applied to teeth, lumber, or the fabled naughty apple. In our environment it may also have positive connotations when applied to waste disposal, to vegetation in the soil-forming process, or to rock. Limestone and its magnesium-bearing cousin, dolomite, may decay through the slow-dissolving action of very weak natural acids, such as carbonic acid formed by the union of carbon dioxide in the atmosphere with rain water, and by organic acids from rotting vegetation. Such natural acids percolating through limestones and dolomites may eventually form large cavities over a span of thousands of years. These cavities may be in the form of caves, water-bearing caves (springs), and sinkholes. Such voids are referred to by geologists as karst features.
The Ozarks owe much to karst features. The numerous springs, clear streams, ancient sinkholes filled with mineral deposits, and caves contributed significantly to luring the early settlers. These features were formed in dolomite, a rock which predominates over limestones in the Ozarks. All of the so-called limestones in our area and south to the Arkansas line are dolomites.
Ozark rocks are highly fractured and as a result the environment is ideal for the formation of karst features. Development is further expedited by the large amounts of chert (flint) in many of these limestones and dolomites. As the dolomite is dissolved, a remaining mantle of relatively insoluble chert and clay is left behind. Rainwater tends to be trapped in this mantle and rather than moving laterally as surface runoff, percolates downward through the clay and chert residue into cracks and crevices of the underlying carbonate rocks to act as a dissolving agent and to feed springs. As a result, many of the smaller Ozark streams do not have surface flow except during times of heavy rains and much of the water moves either within the chert mantle or in openings in the underlying bedrock. This chert mantle undoubtedly is a factor in filtering the water and assuring the clear springs which, in turn, feed clear streams.
The recorded cave count in Missouri is now over 3,313 and a projection of the current discovery rate proves that by the year 2000, there will be a cave count of 7,463. (The mathematically inclined would be interested to know that a backward projection of
this rate proves that no caves were known in Missouri in 1954.) Most Missouri caves are in the Ozark area despite the calculated cave absence before 1954, for history records that the pioneers found and utilized caves in the early 1800s.
This area was blessed with a fair share of the many saltpeter caves in the Ozarks. Saltpeter (potassium nitrate) was formed in caves where bat droppings accumulated. This was a valuable Ozark commodity because gunpowder was manufactured from it combined with charcoal and sulfur. The sulfur was obtained from the roasting of pyrite (fools' gold) or lead ores, both of which could be obtained locally.
According to a publication in the Missouri Historical Review, gunpowder was made in or near saltpeter-bearing caves in 1823 by William Coppedge at Saltpeter Cave northwest of Rolla and at Spring Creek Cave near Relfe west of Edgar Springs. This same publication states that in 1810 saltpeter from caves "along the Gasconade River" was produced for shipment to St. Louis, and as early as 1816 gunpowder was manufactured at Saltpeter Cave in northwest Pulaski County.
Ashley (or Saltpeter) Cave near Montauk Spring was worked from 1816 to 1818 by Gen. William H. Ashley and reportedly produced 60,000 pounds of saltpeter valued at $30,000 which was used in a gunpowder factory near Potosi. The mouths of caves with large openings were Indian shelters and also have served for livestock and implement shelters to modern times. The remnant of a cave, St. James Natural Tunnel, northwest of Maramec Spring was boarded at one end and served as a snug cattle shelter several years ago.
“boarded up at one
end and served as a snug cattle shelter”
St James Natural Tunnel, about 250 feet long and S-shaped.