Under the Bluffs: The Caves

On a hot July afternoon below Steel Bridge, a floater drifting close under the bluffs will now and then pass through a pocket of air so cold it raises goose bumps. Look up, and there is usually a dark opening somewhere in the rock: a slot at the waterline, a low arch with a fan of fallen rock spilling toward the river, a hole high on the cliff where only the vultures go. The cold air is coming out of the hill.

The Jacks Fork runs through cave country. About ten miles of its banks are bluff 50 feet tall or more, eight of those miles above Alley, and the tallest faces stand 280 to 350 feet1 over the water (Chapter 2; Map 13). Missouri has more than 7,500 known caves2, and Shannon County, which holds most of the river, has nearly 600 of them, a number only Perry County3 beats. When cavers working for the Missouri Speleological Survey and the National Park Service went over the Jacks Fork valley in the early 1980s, they wrote up fifty-seven caves and rock shelters and named a few more4 they had heard of or glimpsed. Most are small. Across Missouri, fewer than 3 percent5 of known caves run longer than a mile, and on the upper Jacks Fork a cave of a few hundred feet counts as ordinary6.

A cave, in the cavers’ working sense, is an opening that runs deeper into the hill than it is wide. A rock shelter is the reverse, an overhang wider than it is deep7, with no passage behind it. The Jacks Fork has plenty of both, and the line between them is often a matter of a few yards of crawlway.

Rock that dissolves in the rain

The caves exist because the bedrock dissolves. The hills along the upper river are built of dolomite, a close cousin of limestone made of calcium and magnesium carbonate, which gives way to acid a little more slowly than limestone does. Rain falling through the air picks up a little carbon dioxide, and it picks up a great deal more as it soaks through leaf litter and soil, where roots and rot keep the ground air rich in the gas. The water becomes a very weak carbonic acid8. When that acid meets dolomite, it turns the carbonate of the rock into bicarbonate, which stays dissolved9 in the water and travels off with it. The rock leaves in solution, molecule by molecule, and none of it has to be worn away. Against dolomite that is enough, given time (Chapter 12).

Southern Missouri gets about forty-five inches of rain10 a year, and a good share of it soaks into the ground instead of running off. That water travels through the rock along its cracks: the vertical joints that split the bedrock into blocks, and the bedding planes11, the seams between one layer of rock and the next. Wherever water moves, it eats a little of the rock and widens its own path. A hairline crack becomes a tube the width of a pencil, then a pipe, then a passage a person could crawl through. Water that stands still soon takes up all the rock it can hold and stops dissolving, so the work goes fastest where the water keeps moving, and the steep fall from the Ozark uplands12 down to the valley floors keeps it moving. The process is slow beyond any human patience, and it never stops. Missouri has been called a “cave factory,” because the region may now be in the most intense episode of cave making in its entire geologic history.

Geologists have argued about how and where this happens. Into the twentieth century the textbook view was that caves are carved above the water table, the level below which every crack and pore in the rock is full of water, by streams running through open passages. In 1930, in a long paper on the origin of limestone caverns14, the geographer William Morris Davis13 proposed the opposite, that caves are dissolved below the water table in rock that is full of slowly moving water, and only later drained and opened to the air. J Harlen Bretz of the University of Chicago came to the Missouri Ozarks in 1947 to test the idea, crawled through cave after cave, and came away convinced that Davis was right. His Caves of Missouri, published by the state geological survey at Rolla in 195615, became a classic. He is remembered as a great teacher with a fine sense of humor. His parents had given him no first name, so he added a J in front of Harlen, and since it stood for nothing he wanted no period after it. “Throughout all my life,” he said, “I have fought typists and printers to leave off that damned period.”

Both kinds of cave are now known to form. Some passages grow below the water table beneath a layer of sandstone, where groundwater under pressure is held against the underside of the layer and dissolves the rock just below it. Others, the more common kind, grow above a sandstone layer16, where water seeping downward reaches the sandstone, cannot get through it, and runs along its top. Cavers call a passage dissolved in water-filled rock phreatic, and one shaped by a stream running through it in open air vadose, and a single cave can be both. Jam Up Cave probably began17 as a phreatic cave and has since been much reworked by the stream that runs through it (Reach E). In the Ozarks the dissolving began high in the rock column, in the Jefferson City Dolomite that caps the uplands, and worked deeper over hundreds of thousands of years18 as the land was worn down. Cave making in the region has been going on for tens of millions of years. Many of the caves that are dry and open today drained and filled with air somewhere between a few hundred thousand and perhaps two million years ago19.

The level where caves form

On the upper river the caves keep turning up at the same level in the rock. One entrance sits about twenty feet below the base of the Roubidoux20 Formation, and another passage lies less than fifty feet below it21. Several caves sit right at the contact22 between the Roubidoux and the Gasconade Dolomite beneath it, the line in the rock where one formation ends and the next begins.

The reason is the sandstone. The lowest beds of the Roubidoux are sandstone, which barely dissolves, and the top of the Gasconade is dolomite, which does. Groundwater moving through the hills is held against the underside of that sandstone and spreads sideways along it, dissolving the top of the Gasconade just beneath. The sandstone becomes the ceiling23, and the passage follows the contact along the bedding, sometimes for long distances. In Bunker Hill Cave, between Rymers and Bay Creek, a two-foot layer of sandstone shows in the fallen rock at the climb into the biggest room, and sandstone turns up again at the far end of the cave, the source of the sand in its stream. Along the way the stream runs over scalloped bedrock and a floor of sandy gravel that often becomes pure white crystalline sand, and the passage loops back and forth in a way more typical of the caves of Pulaski County24 than of Shannon County.

Near Blue Spring the contact lies about 900 feet above sea level. Seventy to eighty feet below it, a three-foot bed of fossil algal mounds called the cryptozoon reef forms the floor of a cave entrance just above the waterline, where the ledge juts out into the river (Chapter 1). The reef is a marker bed, a layer that can be recognized from bluff to bluff, and because the top of the Gasconade usually lies seventy to eighty feet above it25, the reef shows where the contact ought to be even in a bluff where the contact itself is hidden.

Deeper in the rock lies a thicker and more important lid, the Gunter Sandstone at the base of the Gasconade. The most complex cave networks26 in the region formed beneath it. Alley Spring comes out of one of these. Divers have mapped more than 3,000 feet27 of flooded passage behind the spring pool, down to at least 155 feet below the surface28. Water held under the Gunter is under pressure from the higher ground around it, and where the sandstone has been broken through, that pressure drives the water up out of a lower cave passage29 and into the pool (Reach H).

Plumbing left high and dry

As the Jacks Fork cut its valley deeper, the water table in the hills fell with it, since groundwater drains toward the lowest outlet it can reach, and on the upper river that outlet is the river. Passages that had once been full of water were left dry and open, high in the bluffs30, while new passages kept growing below at the level where the water stood. So a single bluff can hold a dry cave near its top and a spring at its foot. The dry caves are old plumbing, and the springs are the plumbing in use.

Blue Spring shows both at once. The spring itself comes out of a cave at the base of the bluff, from a rise pool, where the water wells up from below, probably twenty feet deep or more31. Just upstream in the same bluff is Hospital Cave, probably an older outlet of the same system. As the water found a deeper way out, the old outlet was abandoned to the air, and its dry passages probably give a fair idea of what lies behind the spring32 itself (Reach D).

Water also leaves its signature on the walls. Fast water flowing over soluble rock carves it into scallops, shallow spoon-shaped hollows that overlap like the scales of a fish. Each one starts where a small eddy in the current lingers against the rock and dissolves a little more there than around it. Their size tells how fast the water was moving, with smaller scallops marking faster flow, and their shape tells which way it went, since the steep end of each scallop faces upstream. About 110 feet into Moss Spring Cave, between Rymers and Bay Creek, the scallops in the floor are so sharp that kneepads and gloves are needed to keep from being cut, and the party that mapped the cave in 1981 named that stretch the Meat Grinder33.

The river can also break into a cave from the outside. One cave in a bluff above the Jacks Fork was a pocket packed with clay34 until the river, cutting down, reached it and opened it. Floodwater has since flushed out much of the clay and left silt in its place. Other caves near river level fill with every big rise. One has a cracked silt floor35 that shows how often the river floods it, and another is frequently backflooded36, the rising river pushing in at its mouth and filling it from the front.

How caves fall apart

Once a passage is drained, it begins to come apart. Underwater, the rock of a ceiling is partly held up by the water around it. Drained, each slab carries its full weight, and slabs crack loose along the joints and fall, a process cavers call breakdown. Jam Up Cave’s enormous river entrance owes most of its size to it, and great blocks37 still lie across the opening (Reach E). Ceiling falls have happened at Jam Up in recent years38. In many of the small caves along the Jacks Fork, the blocks on the floor probably never fell at all. They were loosened where they lie, weathered apart in place39.

Breakdown can carry a cave all the way to daylight. A passage near the surface loses its roof a slab at a time until a section caves in, leaving a sinkhole, a natural bridge, or a short tunnel open at both ends. In the riverways, sinkholes in the lower Roubidoux have collapsed through its basal sandstone40 into caves in the Gasconade below. In one shelter the back wall is a heap of broken rock that has slid down along a joint and is still unstable. The movement will probably go on until it opens a hole to the surface, and then an arch will stand there with the joint forming its far side, as so many natural bridges and arches do41 in the Jacks Fork drainage. Jam Up, strictly speaking, is a natural tunnel42, a cave open at both ends (Reach E).

Caves also steal water. A cave growing beneath a creek can open a way through the creek bed, so that the creek drops underground and leaves its old channel dry. Cavers call this stream piracy. Jam Up Creek, which heads in Mountain View43, was captured in this way by the cave beneath it, and its flow was diverted underground44. In wet weather the creek runs into Jam Up Cave and comes out again at the river entrance45 (Reach E). The water that sinks in the creek’s bed below Mountain View never comes back to the Jacks Fork at all. It turns up at Big Spring46 on the Current (Chapter 12). At Blue Spring a sinkhole that opened over the old spring system captured a whole hollow, and the cleft it left cut a pinnacle of rock loose from the bluff, which cavers call the rock island47 (Reach D). Bear Cave, on the stretch between Low Water and Steel Bridge, probably pirates water48 from a neighboring hollow.

Stone that grows

A cave that has been drained does not stay bare. Water still seeps down through the rock overhead, carrying dissolved calcite, and when a drop reaches the open air of a cave, it gives off some of its carbon dioxide, the way a bottle of soda fizzes when the cap comes off. With less carbon dioxide in it, the water can no longer hold all of its calcite49, and a thin film of crystal is left behind on the ceiling, the wall or the floor. Cavers call the results speleothems, or just formations. Pure calcite is white. Iron, manganese and the tannins50 of rotting leaves, carried down in the water, stain it red, orange, brown, gray or black.

Every stalactite begins as a soda straw, a hollow tube of calcite exactly the width of a drop of water, hanging from the ceiling. Water runs down the inside and adds a ring at the tip. When the tube clogs, water runs down the outside instead, and the straw thickens into the familiar icicle shape. Where the drip hits the floor it builds a stalagmite up toward it, and if the two meet they make a column. Water running down a sloping ceiling leaves a line of calcite that grows into a thin, folded drapery, sometimes banded like bacon. Water flowing across a floor or wall lays down flowstone51 in layers. In shallow pools, calcite builds rimstone dams around the edges, and grains of sand kept turning under dripping water become coated, layer after layer, into cave pearls. Helictites twist off in any direction at all, fed by water seeping through tiny internal canals52 too fine for gravity to matter.

The Jacks Fork’s caves hold their share. Hospital Cave has an upper level with soda straws. Simpson Hole Cave, below Steel Bridge, had soda straws and draperies when cavers went through it in 2007. Moss Spring Cave has rimstone dams, a natural arch, a six-foot waterfall, and a shelf twenty-five by forty feet53 set with small stalagmites. In one small cave elsewhere on the river, the floor pools that once held cave pearls have dried, and by the early 1980s the pearls were mostly crushed or otherwise disturbed54. The caves of the Riverways region as a whole hold helictites, aragonite crystals, cave pearls, massive flowstone, boxwork, golden calcite and unusually long soda straws55. Some of the park’s caves also hold spathites, which are uncommon in caves outside the park: tubular stalactites built up as a stack of delicate, overlapping cones shaped like petals56.

How fast formations grow depends on how much water is moving and on the rainfall and the temperature outside57, and the rates vary from cave to cave and from century to century. In human terms they barely grow at all. Formation is extremely slow, and damage done to it can stay in sight for generations58. A broken stalactite does not heal, and the oil left by a hand can keep new calcite from forming on that spot. Formations also keep a record of the past. An earthquake can snap a stalactite or topple a stalagmite, and dating such breaks can give the dates of old earthquakes. Formations in Round Spring Cave59 on the Current are being studied for exactly that.

Ozark folk belief gave formations a reputation of their own. Stalactites and stalagmites were held to be somehow deadlier than any other stones, and even a slight blow from a piece of “drip rock”60 was generally thought fatal. Others were less nervous. Between about 1885 and 1925, when cave picnics and dances were popular all over the Ozarks, visitors routinely broke off formations to take home. In the hot months somebody would lay a dance floor back inside a cave, out of the heat62. Stalactites ended up on mantels and in rock gardens, and stalagmites were even set up as tombstones61. As early as 1898 a writer on Ozark caves63 complained that most of them had “been deprived of great quantities of their beautiful adornment by visitors.”

Caves that breathe

Floating down from Mountain View one July, probably in 193464, Ward Dorrance met a man “a-muleback”65 somewhere between Blue Spring and Jam Up. The man tied his jenny to a tree and led the floaters up a hill to what he called a blow-hole: “an aperture twenty-four inches across in the rock of a hill, the ‘skylight,’ evidently, of a cave.” The air pouring out of it was cold enough to bend the branches around it and whip the leaves.

Dorrance had guessed right. Away from its entrances, an Ozark cave holds a nearly steady temperature the year around, somewhere between about 56 and 60 degrees66 Fahrenheit. That is close to the average temperature of the whole year outside, because the rock deep in a hill, insulated by everything above it, settles at the year’s average and holds it through summer and winter alike. On a summer day the air in the cave is colder and heavier than the air outside. If a cave has openings at different heights, the cold air drains out of the lower ones like water from a tipped jug, and warm air is drawn in at the top to replace it. In winter the flow reverses, and the cave breathes in at the bottom and out at the top, where its warmer, moist air can show as a plume of vapor on a cold morning.

The breath of a cave can give it away. In summer a cascade of cool air plunges down the hollow67 from Bunker Hill Cave and gives the cave away. In Hospital Cave a steady wind blows through a squeeze about a hundred feet in. Jerry Vineyard felt that wind around 1971 and suspected a big cave system lay beyond it, and Scott House, who mapped the cave a decade later, felt it and thought the same, until the mapping showed an average cave for the river, 375 feet long with three entrances68.

The caves and the springs

Spring outlets of any size are cave openings that discharge groundwater69. The big springs of the Ozarks are the outlets of cave systems that collect water from wide areas of country and bring it out at the foot of a valley. Some of the oldest caves in the region are probably the deep, water-filled conduits70 that feed those springs, still in the stage of growth that the dry caves in the bluffs passed through long ago.

Both of the Jacks Fork’s great springs come out of caves. Blue Spring, one of the larger springs in the Current River basin, rises in a pool inside a cave71 at the base of its bluff (Reach D). Alley Spring, one of the largest springs in Missouri, sends out water from its flooded cave at a rate given as 81 million gallons a day72 and, from the gauge records, about 87 million73 (Chapter 12). Rain that falls into sinkholes around Summersville, about fifteen miles to the northwest, travels through cave passages under the hills and comes out at Alley. Under the Alley Spring Natural Area those passages hold some of the richest cave life74 known in the state (Reach H).

The connection runs both ways. Whatever goes into a sinkhole or a cave goes into the groundwater, and from there into a spring or a well. For generations sinkholes and caves in the riverways country were used as dumps and as outlets for septic systems75, and the water carried the results downhill under the ground (Chapter 17).

Life in the dark

More than 1,100 kinds of animals have been recorded in Missouri’s caves, among them mammals, birds, fish, amphibians and reptiles as well as a great many smaller creatures. A cave is three different places for them. The entrance zone, out to the dripline where rain falls from the overhang, is still half outdoors. Just inside it is the twilight zone, where some daylight reaches and the air still swings with the weather. Deeper is the dark zone76, where there is no light at all and temperature and humidity hardly change.

The animals sort themselves roughly into three groups. Some only visit, sheltering in the cave but feeding outside: bats, wood rats, the eastern phoebes77 that build their mud-and-moss nests on ledges in shelter mouths, and the vultures that roost in high openings. Some can live either in caves or in cool, damp places outside, such as cave crickets, many salamanders and the small flies that cluster on cave ceilings. A few live only underground. Biologists call these troglobites. They are usually pale and eyeless, with long feelers and slow lives. In total darkness, color and eyesight do an animal no good, and over many generations cave animals lose them and rely on touch and smell instead, while a slow life suits a place where food comes seldom. They live on what water and visitors bring in from outside: leaves, flood trash, bat droppings and the dung of wood rats. With no sunlight in the dark zone, no green plants grow there, so every animal in it depends in the end on food carried in from the surface.

The Jacks Fork’s caves have their full share of the visitors and the part-time residents. Wood rat nests turn up in cave after cave, along with cave crickets, two kinds of spider in one cave, a brown recluse in another, hibernating bats, and heliomyzid flies78 on the walls. Cavers in Jam Up Cave in the 1960s saw cave salamanders and a long-tailed salamander79. Moss Spring Cave is notable for the beauty of its many formations and the variety of its life. In 1981 it held big brown bats, the small bats then called eastern pipistrelles, a frog, cave crickets, salamanders and amphipods80, small shrimplike crustaceans that live in cave streams.

The cave salamander is the one a careful visitor is most likely to notice, a bright orange salamander, usually spotted with black, that lives mostly in the twilight zone and climbs cave walls with its wet body, using its long tail81 to brace itself on formations. The grotto salamander is stranger. Its larvae have working eyes, darker skin and broad tail fins, and they sometimes live in small streams and springs outside caves. The adults are pale tan or pink, with small eyes partly or fully covered by their eyelids, and they live in total darkness in caves with streams running through them. A larva may take two or three years to turn into an adult, sometimes as long as six, and an adult lives at least nine years in the wild. The larvae will occasionally eat bat guano, and the species is most abundant in caves with many bats, probably because of the insects that the guano draws. The grotto salamander lives nowhere outside the Ozarks82, and on genetic evidence it is now divided into two species, a northern and a southern grotto salamander.

The rarest life is in the water. In the mid-1930s Dorrance saw three blind fish in the pool of Blue Spring’s cave, probably southern cavefish, which were recorded at one site in the Jacks Fork basin in 199283 (Reach D). What was once called the southern cavefish has since been split into several species that look nearly alike, and the cavefish of the Missouri Ozarks’ Salem Plateau, the country the Jacks Fork drains, is now called the Salem Plateau cavefish. It is a small fish, an inch and a half to two and a half inches long, with a long, flattened head and no eyes, and it has so little pigment that the blood under its skin makes it look pinkish white. It eats tiny crustaceans, small crayfish and the larvae of water insects, and its slow metabolism lets it go a long time between meals. It is believed to spawn when the water is high, from February through April, and the female carries her eggs, as many as fifty, in her gill chamber for four or five months until they hatch. A cavefish probably lives more than ten years84.

The Salem cave crayfish85, a pale crayfish that lives underground and turns up at the mouths of large springs near the limit of daylight, has been recorded in the watershed and is ranked as imperiled across its whole range. That range lies entirely in Missouri, in a broad band of the eastern Ozarks from Camden and Crawford counties south to Oregon and Ripley, and includes the Current and Eleven Point drainages. The crayfish is blind and a translucent white, two and a quarter to nearly four inches long, with long, narrow pincers and very long feelers. An animal with so small a range, living in water that comes down from the surface, can be badly hurt by a single accident, and in 1981 one fertilizer spill that seeped into the ground killed thousands86 of them. Under the Alley Spring Natural Area at least seven troglobites live in the cave passages, including the grotto salamander, and Branson Cave there is one of the most biologically diverse caves87 known in Missouri.

The bats. The cave animal with the most at stake on the Jacks Fork is the gray bat. Missouri holds about a fifth of the whole species, and the latest statewide count came to 541,51889 gray bats. Gray bats depend on caves the year around, using warm caves that trap heat for their summer nurseries and cold caves that trap cold air for the winter. A cave traps warm air where its ceiling rises into domes higher than its entrances, since warm air rises and has no way out, and the packed bodies of the mothers add their own heat. It traps cold air where its passages run downward from the entrance, since cold air sinks and settles. The bats are choosy about it: across the species’ entire range, 98 percent of gray bats hibernate in just fifteen caves, packed into colonies that can number in the hundreds of thousands. In summer they hunt over water, following rivers and streams out to their feeding grounds and catching insects on the wing, including the Asiatic oak weevils that swarm in the forested cliffs along rivers. The species has been recorded in the Jacks Fork watershed90.

Gray bats were listed as endangered in 1976, after their numbers fell sharply, mainly because people disturbed their roosts. They are extremely sensitive. Even someone walking carefully through a cave with a light can send them into the air, and a single disturbance can wreck a colony’s breeding for the year. Protecting their caves has worked. The species is still listed as endangered but is recovering well88, and by 2023 it was holding strong throughout its range91.

The endangered Indiana bat92 also uses caves in the riverways. It was on the first federal list of endangered species, published in March 196793. In winter it needs a cave that holds steady at about 40 degrees and stays damp, and there hundreds of bats pack into a few square feet of ceiling. In summer it leaves the caves for the woods along streams, where it roosts under loose bark on trees such as shagbark hickory94. That summer habit carried the bat’s protection out of the caves and into the timber. At the end of the 1990s the Indiana bat was the subject of a quarrel over timber sales95 in the Ozarks, and a local timber man described it from the woods’ side. “They found a few bats in the bat caves,” he said, and while the government studied whether cutting timber harmed the bat, “they shut all these sales down.” He wondered why the boats did not count against the bat as well: “the caves are right next to the rivers.”

The small bats once called eastern pipistrelles are now called tricolored bats, for the three colors banded along each hair. They hibernate alone or in pairs rather than in colonies, and in damp caves they are often found beaded with dew96. All of these bats live on insects, and by one estimate of 2011, losing North America’s bats would cost the nation’s agriculture more than $3.7 billion a year97 in crop and forest pests.

Bears. Before settlement black bears were common in the Ozarks, and bones from Missouri caves show that they routinely wintered in caves, often in groups. They were rare by the 1850s and gone from most of the state by the 1880s, but they left their name behind. Forty-three Missouri caves have “Bear” as the first word of their names, plain Bear Cave being the most common of them, and Shannon County has eleven “bear” caves, more than any other county. The Bear Cave on the stretch between Low Water and Steel Bridge is one of the larger caves in the valley, about 550 feet long, with a stream passage that runs back to a pool where the ceiling meets the water99. Black bears have since come back into the southern Missouri Ozarks from Arkansas98.

Older bones lie deeper. Caves in the riverways country have yielded remains of animals from the last ice age, among them the giant short-faced bear, probably the most dangerous bear Missouri ever had101, jaguar, a stilt-legged deer, the dire wolf and a giant armadillo. The dire wolf came from Powder Mill Creek Cave100 on the Current River side of Shannon County.

What people did with caves

Before settlement. People were using Ozark caves and rock shelters for thousands of years before the first settlers arrived. A dry shelter in a bluff above a river offered a ready camp, out of the rain and the wind and close to water and game. Caves were also sources of chert for tools, of clay for pottery, and of water, and some held burials. About a third of Missouri’s known rock-art sites102 are on the walls of caves and shelters. By the late 1990s, 215 caves on fourteen tracts across the park’s main karst formations had been examined for signs of people, and thirty of them showed prehistoric use and nine103 historic use (Chapter 3). Dry cave deposits can preserve things that rot away anywhere else, because with no water and little moving air the molds and bacteria of decay can barely work. At Arnold Research Cave in central Missouri they kept shoes woven from plant fiber for about nine thousand years104.

Those deposits are what looters dig into. Deep holes in the entrance room of Bear Cave are probably the work of amateur archaeologists105. A cave floor builds up in layers, the oldest at the bottom, and what a site can tell depends on which layer each thing lay in and what lay beside it. Digging the floor for arrowheads churns the layers together, so that the record of when people were there and what they did is gone, and the damage cannot be repaired. Disturbing a human burial in Missouri, marked or unmarked, is a felony106.

Farm and home. For the families who settled the hollows, a cave with a spring in it was a cellar, a cooler and a water supply. Rural electricity reached parts of the Ozarks only in the early 1950s108, and until then the steady cold of a cave did the work of a refrigerator. Milk, butter and cheese set in a trough of cold spring water kept far longer than they would in the house. Families walled up cave entrances to keep out animals, hung doors in the walls, and built small dams inside caves or across their mouths to hold back the spring stream. Caves were still being turned into springhouses and water supplies as late as the 1950s. More than two hundred Ozark caves still show the evidence: crumbling dams, walled entrances, pipes, troughs, shelving and old water tanks. Shannon and Texas counties are both on the list. Caves also kept potatoes and apples through the winter. Shannon County has a Potato Cave, and Texas County has two Sweet Potato Caves107.

Just inside the mouth of Blue Spring’s cave are the broken remains of a concrete dam, by one account dated 1938109, whose purpose is unknown110, and by 2007 an old retaining wall111 had fallen into the rise pool. No record yet says who built them or why (The Open Ledger). Dams like it were a common way to pool a cave spring for water or cooling.

War, stills and treasure. During the Civil War, caves in the riverways country were dug for saltpeter to make gunpowder, used to hide county records, and used as refuges112, and some stories of those years have attached themselves to Jacks Fork caves (see “The stories,” below, and Chapter 6). Saltpeter, potassium nitrate, is the part of gunpowder that feeds the burning, and the dry earth of an old cave floor, enriched over centuries by the droppings of bats and wood rats, holds nitrates. Diggers carried the cave dirt out and soaked it in hoppers, ran the water through wood ashes, which turn the nitrates into saltpeter, and boiled the liquor down113 until crystals formed. Across the Ozarks making saltpeter and gunpowder this way was a cottage industry114. A cave with a spring in it was also an ideal place for a still: cold water, steady temperature, shade and privacy. More than forty caves in Missouri, spread over twenty-three counties, have a surviving story or physical trace of brewing or moonshining, three of them in Shannon County115. In one Jacks Fork cave lies the base of an old copper kettle, rusted through, quite possibly the remnant of a still. Moonshining was very active along the Jacks Fork116 before, during and after Prohibition, the years from 1920 to 1933 when making and selling liquor was against federal law.

Ozark caves attract treasure stories, and more than one Missouri cave is named for them. The stories usually involve Spanish gold, Civil War loot or a lost silver mine, a hidden room and a map, and by the legends Jesse James hid out in nearly every cave in the state118. Camped on the Current near Van Buren119 in the mid-1930s, Dorrance listened to the hill people’s treasure talk, of buckskin maps, pine knots buried in significant positions and arrows scratched on walls. To hear some of the hillmen tell it, there was no cave “in which Frenchman or Spaniard, Confederate or Yankee, or simple train robber, did not bury treasure.” One of the stories he heard was about the people who cannot dig it. Old Jake Hepburn, the story went, came to the mouth of a cave hunting gold, and at once the wind blew, the day grew dark and the earth trembled under him. He caught his mare and left, decided on reflection that it had been a plain, ordinary earthquake, and went back, and before he could get out of the saddle he was driven off the same way. The teller finished: “Yessir, Leo, I reckon they’se folks that hadn’t better go foolin’ around with no treasure diggins.”

The bedrock of the Ozarks does not hold veins of gold or silver, and no one has ever found treasure in a Missouri cave. The digging, though, has done real harm, wrecking archaeological deposits and fossils and leaving spoil piles117 behind.

Visitors. Before 2010 most of the park’s caves were open to anyone who could reach them, and people used them hard. By 1981 many people went into the front rooms of Bunker Hill Cave, and at least one vandal with green spray paint120 had already reached the back. That same year the squeeze in Hospital Cave’s passage was already polished by the passage of many bodies121. By 2007 its floor was packed hard by foot traffic, and the dripstone there had turned browner122 than it was four years before. Simpson Hole Cave held the remains of a campfire and some broken formations that year, and the cavers who went through it then thought it visited heavily enough to need a gate123 (Reach D). Volunteers from the Springfield Plateau Grotto and the Cave Research Foundation have since reattached at least seventy-eight broken formations in Shannon County caves and filled in looters’ holes, and restoration work has been done in up to thirteen caves. The Park Service began putting gates on some entrances in the mid-1980s124. A well-built cave gate is a grid of steel bars spaced so that bats can fly through it and people cannot.

The stories

Hospital Cave. The best-known cave story on the Jacks Fork is a Civil War story, and its paper trail is short enough to follow to the end. On his float of the mid-1930s Dorrance passed a “yawning hole in the bluff”125 just above Blue Spring and wrote: “There is a crudely lettered sign: Hospital Cave Civil War. History, of course, has no memory of this place.” Then he imagined wounded soldiers by candlelight anyway.

Five years later Anna O’Brien, a University of Missouri graduate student collecting the place names of five south-central Missouri counties, listed Hospital Cave as “a cave on Current River. Named because126 the cave was used as a hospital during the Civil War.” Her one source was Dorrance’s book, the same passage in which he had said history had no record of the place, and she put the cave on the wrong river. By 1977 the Park Service’s river folder stated the story as fact: “In the bare-rock cliff on the left127 is Hospital Cave where at various times during the Civil War both Northern and Southern soldiers were given care.” The Park Service’s place-names page now says the cave “was supposedly used as a hospital during the war.”

The cavers of 1980 to 1982 found Hospital Cave listed in the state cave files at the wrong place, up a hollow in rock much less likely to hold caves, and could not learn who had reported it128. They mapped it under that name and gave no story for it. Nobody has yet established who painted the sign or what they had heard (The Open Ledger). No wartime letter, report or diary naming a hospital in the bluff above Blue Spring has turned up, though wartime hospitals did exist in the region, among them the courthouse at Old Eminence on the Current in February 1863129 (Chapter 6).

Meeting House Cave. Downstream between Jam Up and Rymers, Meeting House Cave opens with one of the largest entrances on the river and about 220 feet of passage130 behind it (Reach E). The 1977 Park Service folder gave its story as legend from the start: “According to legend131, this cave was used as a hideout by both sides during the war.” By another account it was a meeting place in the troubled days132 of the War Between the States, and the name is generally said to come from the Civil War period133. Elsewhere in Missouri, Union and Confederate forces did sometimes use a cave entrance as a meeting point134. In older American usage a meeting house was also a house of worship136, and the name may remember a church gathering as well as a war council135 (The Open Ledger).

Peter Renfro. The cave story with the best documents behind it belongs to Peter Renfro, whose name is also spelled Renfrow, a man from near Summersville. On July 18, 1888, about six in the evening, at Summersville, he shot and killed Constable Charles D. Dorris137. The accounts agree on the killing, on a cave near home where Renfro hid out, on a break from the Springfield jail, on his capture in 1898138, and on a governor’s mercy at the end. They disagree on many of the dates in between (The Open Ledger).

In the fullest telling, drawn from the newspapers of the time, Renfro and his brother Will confronted John Hughes, a witness in a lawsuit against Will. Dorris arrested Will, and Peter, drunk, drew a pistol and shot the constable over the left eye. Dorris died within the hour. Renfro gave himself up five days later and was moved to the Springfield jail on a change of venue140, which sends a trial to another county when a fair jury is unlikely at home. With his trial set for late 1889, he broke out with other prisoners and went to ground in a cave near home. Its mouth was on the face of a cliff, reportedly reachable only from above142. He kept a Winchester, two revolvers and a dog, and friends brought him food. After about a year two of his cousins and a deputy sheriff dropped on him from above while he slept at the cave mouth, and he was back in Springfield on August 6, 1891.

He was convicted and sentenced to hang, and on October 10, 1892, the Missouri Supreme Court upheld the conviction141. Stays pushed the date back to February 7, 1893, and in late January 1893139 he escaped again in a mass break from the Springfield jail. That summer the Current Wave143 ran a story on his cave hideout, and a newspaper account of 1893 described the hideout but would not say where it was144. In February 1898 a deputy U.S. marshal arrested Renfro at the old Doniphan club house in northern Ripley County145, where he had married and settled, though a Michigan paper that month placed the capture in Lawrence County, Arkansas146.

Back in Springfield he was sentenced to death a second time. A petition went around southern Missouri asking for mercy, and the evidence suggested drink and temper rather than a plan. In May 1898 Governor Lon V. Stephens commuted the sentence, to life by one account147 and to twenty-five years by another. By the second account Governor Alexander Dockery cut the term to end in May 1905 after another petition, and that summer the Springfield paper reported Renfro at an Independence Day barbecue and wished him a useful, settled life. He is buried near Summersville148.

At least two caves carry his name. Peter Renfro Cave is about 220 feet long and very hard to find, even in winter, and the rusted kettle lies in it. The government topographic map shows the cave in the wrong place, a local resident once said the “real” Peter Renfro Cave was on a different hillside, and Renfro had so many caves to choose from that he probably used several149. A second, Peter Cave150, is reportedly named after him as well.

Mapping the caves

For most of Missouri’s history nobody had any idea how many caves the state held. A state museum curator in the 1920s compiled one of the first lists and came up with seventeen, all of them show caves151. In the fall of 1956 three men, Oscar Hawksley, a biology professor at Warrensburg, Frank Dahlgren, a St. Louis metalworker, and Jerry Vineyard, then a geology graduate student at the University of Missouri, came home from a national caving convention in Nashville and founded the Missouri Speleological Survey to locate, record, explore, map and study the caves of Missouri. They started with a list of 437 known caves. The Survey arranged with the state geological survey at Rolla to keep its maps and reports in a permanent repository, and over the next fifty years its members added more than 120 caves a year to the state’s files. In 1985152 the Survey received a President’s Volunteer Action Award at the White House for that work.

Vineyard, born in 1935 near Dixon, had grown up in the hills of Pulaski County. In 1957 he was one of four compilers of the state survey’s Catalogue of the Caves of Missouri154, and he spent forty years with the state’s geologists at Rolla, retiring as assistant state geologist. With a federal hydrologist, Gerald Feder, he wrote Springs of Missouri, first published in 1974155, and he remained a caver, with a particular interest in the cave survey, until he died in 2017153. Hawksley, the biology professor, also wrote the float guide Missouri Ozark Waterways156 (Chapter 9).

Mapping a cave is slow, wet, careful work. A survey team moves through the cave from one station to the next, measuring the distance between them with a tape and the direction and slope with a compass and clinometer, while one member sketches the walls, floor and ceiling at each station. Back home the numbers are reduced to a line plot and the sketches drawn up over it into a finished map. Cavers name what they find, often for what they see or for what happened to them there. One party in 1975 named a cave for a place in The Lord of the Rings158, and the name was later dropped as “not appropriate.”

In May 1980 the Survey began a study of the caves of the Ozark National Scenic Riverways for the National Park Service, directed by R. Scott House. By 1982 its teams had found nearly a hundred caves159 in Texas, Shannon and Carter counties that had never been catalogued. The Jacks Fork results filled a double issue of the Survey’s journal, Missouri Speleology, titled Caves of the Jacks Fork Valley and edited by William R. Eddleman. In the early 1980s the Survey and the Cave Research Foundation157 also inventoried caves on other government lands across the state.

The work was done mostly in winter, when the leaves are down and a cave mouth can be seen across a hollow. Cavers from the Southeast Missouri Grotto were already mapping caves in the Leatherwood Creek valley in December 1979160. On December 29, 1980, House, Eddleman and Mike Wetzel worked the caves around Buck Hollow and Blue Spring, and they dated their reports New Year’s Day161. Robert L. Taylor, Chris King and Mike Younkin spent October 17 to 19, 1980, mapping Jam Up Cave and measured 1,749 feet162 of passage. Other names recur on the maps: Joel Laws, Jerry Wagner, Leonard Butts, George Katich. The issue gathered older reports too. Tom Tucker and Lang Brod had described Jam Up in April 1963 and August 1967163, and Vineyard had written up a small cave in the pinnacle at Blue Spring in March 1971164.

Some of the reports have the dry humor of people who have crawled a long way for very little. One small cave was “barely worth the effort.” Of a cave with a waterfall near its stream, a surveyor wrote, “Some people feel that the waterfall165 feeds the cave stream but I believe that the stream feeds the waterfall.” Getting into some of the caves took real nerve. At one bluff cave reached by a vertical climb of fifteen or twenty feet, only one member of a party of four made it up, and he got back down “by leaping into the limbs of a tree166 and sliding down the trunk.”

Some leads came from the Park Service. In 1975 a park employee, Loyd Rainbolt167, steered cavers to one well-hidden cave, and a room in another cave was later named for him. The valley of Leatherwood Creek, which comes in below Rymers, yielded about twenty caves and shelters to the survey. Its owner had posted the land, and the Survey printed the request plainly: nobody should visit168. The issue closes with the society’s motto in capital letters, “CONSERVE MISSOURI’S CAVES.”

A generation later the caves were still being checked. In April 2007 a party from the Kansas City Area Grotto, nine people in four canoes and a kayak, floated twenty-four miles from Buck Hollow to Alley Spring in three days with a list of caves from Scott House169, then working for the Park Service. They looked for each cave, recorded where it was, photographed it, and noted the animals in it and the damage people had done. By 2016 the mapped passages in the park’s caves added up to about twenty-eight miles170.

Counting the caves

Every count of caves on the Jacks Fork and in Shannon County is a count of what had been found and recorded by a certain date, and the numbers rise as cavers keep searching. A partial catalogue of 1952 gave names and locations for 210 caves in all of Missouri. The catalogue of 1957 counted 686 caves in fifty-seven counties, with 25 in Shannon County, 26 in Texas County and 3 in Howell171. In 1982 Shannon County had “over 300”172 known caves. In 1990, the year Missouri passed 5,000 catalogued caves, the county had 403173, by April 2007 it had 571174, and it now has nearly 600175. Missouri passed 7,000 documented caves in January 2016176 and had more than 7,500177 by 2023. The caves identified inside the national riverways are given as more than 300178 and as more than 400. At the higher figure the riverways hold more caves than any other unit of the National Park System, sixty of them with permanent streams and seven179 with lakes. The state’s natural heritage records list twenty-three caves180 in the Jacks Fork watershed itself.

The closure

In the winter of 2006 to 2007181, hibernating bats in New York were found dying with a white fuzz on their muzzles and wings. The fuzz is a fungus, Pseudogymnoascus destructans, that grows in the cold, damp air of the caves and mines where bats hibernate. A hibernating bat lets its body cool nearly to the temperature of the cave and slows its heart and breathing, and in that state the fat it put on in the fall can carry it to spring. The fungus wakes the bats again and again through the winter, each waking means warming the body back up, and every warming burns fat they need to last until spring. Whole colonies starve. The disease, called white-nose syndrome, has killed millions of bats, and by the end of 2025 it had been confirmed in forty-one states and five Canadian provinces182. It is about 90 percent fatal to the bats that catch it. It does not affect people, but people can carry the spores183 from cave to cave on boots, clothing and gear.

The fungus reached Missouri in the spring of 2010. In April it was found on a little brown bat in a privately owned cave in Pike County. In May researchers found it on five gray bats and a northern long-eared bat netted outside a public cave in Shannon County, though none of them was yet sick. The first confirmed cases of the disease in Missouri came in 2012, in Lincoln County184, north of St. Louis: a little brown bat from one public cave and two tricolored bats from another, confirmed by the federal wildlife health laboratory at Madison, Wisconsin185. The losses since have been severe. Missouri’s tricolored bats declined by 86.8 percent186 between the winters of 2010–11 and 2016–17. Surveys of 375 Missouri caves and mines in 2015 counted 2,684 northern long-eared bats, and a survey of 300 sites two winters later found seven187.

The Park Service did not wait for the disease to arrive. In 2010 it closed every cave188 in the national riverways to visitors, “all caves along the Current and Jacks Fork Rivers,” whether gated or not. Apart from Jam Up, the exceptions are on the Current: the guided lantern tours of Round Spring Cave, led by park staff, Big Spring Cave, which is open, and Cave Spring, open as far as the shade line190 inside its mouth. Devils Well, a karst window where the roof of a cavern fell in over an underground lake189 about 400 feet long and up to 200 feet deep, one of the largest cave lakes192 in the country, is seen from a platform reached by a stairway191 and is not entered (Part Six).

The 1977 river folder had sent floaters to Jam Up to see “a falls and pool inside the cave.” Jam Up is partly open again. As of 2026 the Park Service allows visitors arriving by boat into the river-facing section193 of the cave as far as the pool at the foot of its underground waterfall, the “Forbidden Pool,” and asks them to go no farther (Reach E).

What a cave can do to a person

Caves are hard on people. The temperature barely changes, the water in a cave stream is as cold as the rock, and wet clothes draw heat from the body far faster than dry ones, so a wet, chilled caver can slide into hypothermia in what feels like a cool room. Beyond the twilight zone the darkness is total, and a party that loses its lights is in serious trouble, which is why experienced cavers carry at least three dependable sources of light194 apiece. Floors are slick with mud and littered with breakdown, passages pinch down to crawls, and reaching many entrances on the Jacks Fork means a climb up a crumbling bluff or a scree slope. Caves near river level and caves that take in creeks flood quickly in heavy rain. Large logs clutter the Jam Up Creek entrance of Jam Up Cave, and cavers in 1963 could see that it floods during heavy rains195.

The law, and the silence about locations

About seventy percent of Missouri’s documented caves are on private land. Among cavers it is the caver’s own responsibility to find out who owns a cave and to get permission196 before going in.

On park land the closure carries the force of federal regulation, and violating a park closure is itself an offense197. Missouri’s Cave Resources Act of 1980198 protects caves on any land. Breaking, carving or marking a cave’s walls or formations without the owner’s written permission is a class A misdemeanor, and so is breaking into or tampering with a cave gate199, whether or not the person goes in. Using a cave or spring to dispose of sewage, trash or chemicals is a separate offense200. The federal Cave Resources Protection Act of 1988 covers significant caves on federal land. Damaging one, removing anything from it, or entering it intending to do either can bring up to a year in prison for a first offense and three years201 for a second.

The same federal act bars agencies from releasing the specific location202 of a significant cave unless doing so would further its protection without putting it at risk. Saying little about where caves are is an old custom. In 1893 a newspaper account203 described Peter Renfro’s hideout and kept its location to itself. The Speleological Survey keeps its maps and location files with the state geological survey, and it published its 1982 survey of the Jacks Fork with a request that nobody visit204 the valley where it had found the most caves. When the first confirmed cases of white-nose syndrome turned up in Lincoln County in 2012, the names and locations of the two caves were withheld205.