Caves and Karst

Photo of interior of Jacob's Cave showing a variety of speleothems.

With more than 7,000 caves, Missouri is known as "the Cave State." This is because much of Missouri is a karst landscape of porous limestone and dolomite, where caves, springs, sinkholes, and natural bridges form. These features support unique communities of animals, including threatened and endangered species.

The word karst is the German name for the Krš (or Kras) region on the border between Slovenia and Italy, which has a similar limestone topography. It’s used to describe this type of unique geology of caves, sinkholes, and springs, no matter where on Earth it occurs.

The Karst Cycle

Slightly acidic groundwater flows through cracks in limestone or dolomite, slowly dissolving the rock. The cracks widen to form cavities and eventually a subterranean drainage system. The creeks that flow through caves come from surface water that has seeped downward.

When a cave is below the water table, it is filled entirely with water. (Well-drillers search for these water-filled pockets.) When the cave is above the water table, the cave has air in it and its water flows ever downward. Wherever cave water exits the rock and flows into the open air, it is called a spring.

Some of our largest caves formed ages ago as completely water-filled cavities. Over geologic time, the Ozark Plateau was uplifted, and rivers carved valleys ever deeper into the bedrock, creating bluffs and causing cave passages to be above the water table and to drain.

As the slightly acidic water continues its etching of the rocks, sinkholes can occur where the roof of a cave, and the soil above it, collapse downward into the cave system. When rainwater collects in these depressions, sinkhole ponds form.

When an otherwise normal surface creek disappears underground, emptying into the water table below, it’s called a losing stream.

Natural bridges in karst landscapes represent the last vestiges of an otherwise completely collapsed cave.

Inside a cave, the formation of speleothems (stalactites, stalagmites, soda straws, dripstone, flowstone, and so on) represent the cave’s old age, as water crystallizes previously dissolved minerals, basically reversing the cave-making process, slowly filling the cave back up with rock.

All the land through which water moves into groundwater or into springs or caves is called a recharge area. For a single cave system, this area can be many miles wide. Pollutants, such as agricultural chemicals and animal waste, roadway runoff, leaking septic tanks, contaminants from trash thrown into sinkholes, and even excess silt from a variety of construction and agricultural earthworks, can seep into the groundwater, polluting caves, springs, and well water.

Karst Features

Cave and karst ecological communities are interdependent and often overlap. Browse Aquatic Caves, Sinkholes and Sinkhole Ponds, Springs, and Terrestrial Caves under Related Habitats below.

 

Most of our caves are in the Ozark Highlands ecoregion, where they occur in soluble dolomite or limestone. Caves also occur in sandstone or igneous rocks and may be found in the Osage Plains and Central Dissected Till Plains ecoregions. There are almost no caves in northwestern Missouri and in the Bootheel lowlands.

Photo of the natural bridge at Clifty Creek CA
The natural bridge at Clifty Creek CA is part of a collapsed cave system.
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Photo of the natural bridge at Clifty Creek CA
Building on Karst: Best Practices
Photo of path rush, closeup showing drying fruits.
Rushes
Juncus spp. and Luzula spp.
Missouri has 24 species in the rush family. Distinguishing between these grasslike plants can be tricky, but it’s easy to learn some basics about the group.
Photo of eastern woodland sedge plant growing among leaf litter.
Sedges
Carex, Schoenoplectus, Scirpus, and other genera
Missouri has more than 200 species in the sedge family. Distinguishing between these grasslike plants can be difficult, but it’s easy to learn some basics about the group.
Photo of a bristly cave crayfish, viewed from the side.
Bristly Cave Crayfish
Cambarus setosus
The bristly cave crayfish is a whitish crayfish with small, unpigmented eyes and long, slender pincers with noticeable setae (bristles). It lives in caves in the Springfield Plateau region of the Ozarks.
Meek's Crayfish
Meek's Crayfish
Faxonius meeki (formerly Orconectes meeki)
The pincers of Meek's crayfish are sprinkled with many blackish spots. There is a dark spot near the tubercle at the base of the moveable finger. In Missouri, this rare crayfish occurs in only a few tributaries of Table Rock Lake in Stone County.
Photo of a pink planarian on a rock.
Turbellarians (Planarians; Free-Living Flatworms)
Dugesia, Planaria, and other genera
Unlike their parasitic cousins in the flatworm group, turbellarians, or planarians, are tiny carnivores or detritus-eaters that glide smoothly across submerged leaves and other objects.
Image of a deceased pseudoscorpion on a US dime
Pseudoscorpions
Various species in the order Pseudoscorpionida
Pseudoscorpions are unusual little arachnids. They look something like tiny scorpions but with a rounded (and nonvenomous) hind end. They're common but often overlooked.
Greenhouse camel cricket resting on a white-painted surface
Camel Crickets (Cave Crickets)
About 150 species in North America north of Mexico
Camel crickets and cave crickets are odd-looking, hump-backed insects that are commonly found in caves, basements, cellars, and similar places.
Photo of an adult stonefly on a leaf
Stoneflies
Nearly 700 species in North America north of Mexico
Stoneflies have a lot in common with mayflies, caddisflies, dragonflies, and dobsonflies: They begin life as aquatic larvae, then molt and become winged adults. Many fish find stoneflies irresistible, and anglers know it.
Grotto sculpin side view photo with black background
Grotto Sculpin
Cottus specus
The grotto sculpin is a rare fish adapted cave conditions. It has recently been designated an endangered species under the Federal Endangered Species Act. It's found only in Perry County, Missouri.
Ozark cavefish side view photo with black background
Ozark Cavefish
Amblyopsis rosae
The Ozark cavefish is small, colorless, and blind. It lives only in springs, cave streams, and underground waters. It has been declared Endangered in our state and as Threatened by the U.S. Fish and Wildlife Service.
Image of a cave salamander
Cave Salamander
Eurycea lucifuga
The cave salamander is a common amphibian of the Ozark Plateau. It lives in caves, springs, and rocky streams. Recognize it by its normally bright orange skin dotted with dark brown or black spots.
Image of a grotto salamander
Grotto Salamander
Eurycea spelaea
The grotto salamander is Missouri’s only species of blind salamander. A true troglobite, it lives in total darkness and has small eyes that are completely or partially covered by their pink or beige skin. Occurs in wet caves in the Ozarks.
Silver-haired bat in flight.
Bats
About 14 species in Missouri
Bats are the only mammals capable of sustained flight. At least 14 species of bats occur in Missouri; they are all relatively small, and they eat insects. Many of them are declining.

Aquatic Caves

Cave Spring
Aquatic Caves

Caves with creeks, groundwater, or springs are known as aquatic or wet caves. Many rare and vulnerable animals call these dark, wet tunnels home.

Terrestrial Caves (Dry Caves)

Photo of the opening to a small terrestrial cave on the side of a bluff.
Terrestrial Caves (Dry Caves)

Created long ago by water, but now high and dry, terrestrial caves offer shelter to a variety of animals. These caves are especially important to bats, many species of which are declining.

Sinkholes and Sinkhole Ponds

Sinkhole
Sinkholes and Sinkhole Ponds

Sinkholes, just like the caves beneath them, are common in regions with karst geology. When sinkholes are blocked and form ponds, they support unique wetland communities.

Springs

Photo of Alley Spring's pool of blue water.
Springs

Springs are openings in the ground or rock where underground streams or seeps release water into caves or on the ground. Missouri has many great examples of springs.