Terrestrial Caves (Dry Caves)

Photo of the opening to a small terrestrial cave on the side of a bluff.

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.

Long ago created by water, but now high and dry, terrestrial caves are home to a variety of animals, but because of the dark, very few plants. Many mammals, including foxes, skunks, and bobcats, seek temporary shelter in these caves. The basis of the food chain in such caves is not plants but organic detritus, including corpses of cave animals and dung. Dry caves’ most famous inhabitants are bats. Gray bats and several other bat species roost in terrestrial caves, and the nutrients in their guano are the foundation of a diverse animal community.

Terrestrial caves are often linked with bluffs and glade habitats, with their important plant and animal species, and with riparian (streamside) habitat below. Many dry caves contain — or used to contain — prehistoric human artifacts. It is illegal to remove, damage, or destroy such archeological treasures.

Caves, springs, sinkholes, and natural bridges are all features of karst regions. Much of Missouri is a karst landscape of porous limestone and dolomite with deep fissures.

How Terrestrial Caves Are Formed

In karst regions like ours, caves are formed when slightly acidic groundwater seeps down 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.

Sometimes, due to the continuing dissolution of the mildly acidic water, the rock and soil above a cavern collapses downward, creating a sinkhole.

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.

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.

When a cave passage is elevated high enough above the water table, the cave floor is usually never saturated with water — this is a terrestrial, or dry cave.

Terrestrial Cave Subtypes

Understanding some subtypes will help you understand the category as a whole.

Dry Caves

Dry caves are raised high enough above the water table that there is no significant or permanent water. However, in different areas within the cave, there can be varying amounts of moisture and humidity, depending on rainwater entering the cave and how the air flows within the passageways.

Entrances to dry caves usually occur on elevated hillsides, on high cliffs or bluffs, or in crevices. Passages usually branch inward with increasing complexity, like the branches of a tree.

Examples include Mark Twain Cave, Missouri's oldest commercial show cave. Rich with human history, it is a designated National Natural Landmark.

Dry Pit Caves

Dry pit caves are vertical shafts related to sinkholes, cliff crevices, or a fracture along a joint in bedrock. These openings descend to fairly dry cave floors, which are often littered with leaves, twigs, and surface soil that have fallen in from above. Animals occasionally fall into these pits and die from their injuries or from starvation; their bones often can be found among the other detritus that has collected.

Most dry caves and dry pit caves occur in the Ozark Highlands, especially on exposed cliffs in the Glaciated plains, especially in the Lincoln Hills.

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.
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 pickerel frog
Pickerel Frog
Lithobates palustris (formerly Rana palustris)
The pickerel frog is medium-sized, with square or rectangular spots in two parallel rows down the back. There is a distinct ridge of skin along each side of the back. It is absent from the northwestern third of Missouri.
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.
Raccoon in tree
Raccoon
Procyon lotor
When you see the black mask and striped tail of this medium-sized mammal, you know you’ve spotted a raccoon. These nocturnal omnivores are clever and adaptive.
Photograph of a striped skunk walking
Striped Skunk
Mephitis mephitis
Skunks are omnivorous mammals notorious for their ability to discharge an obnoxious scent when provoked. The striped skunk is the most commonly encountered skunk in our state.
Photo of bobcat
Bobcat
Lynx rufus
The bobcat is a short-tailed wild cat with a distinctive streaked and spotted pattern, a wide face, and pointy ears often with black tufts.
Image of a mountain lion
Mountain Lion
Puma concolor
Mountain lions hadn't been seen in Missouri since 1927 — but in 1994, conclusive physical evidence proved they are reappearing in our state. These animals probably are individuals dispersing from other states, and no breeding population seems to have been reestablished.
Photo of two bears
American Black Bear
Ursus americanus
One of the largest wild mammals in Missouri, the American black bear is unmistakable with its black fur and powerful bearing.
photo of a red fox
Red Fox
Vulpes vulpes
The red fox is doglike, with a long, pointed muzzle; large, pointed ears that are usually held erect and forward; moderately long legs; and a long, bushy tail. It occurs statewide but is more common in the northern and western sections of Missouri.
coyote walking through grassland
Coyote
Canis latrans
The coyote is a much-maligned member of the dog family. It does a great service to the ecosystem by helping to hold populations of rabbits and mice in check. In addition, their yips and barks add to nature's music in rural nights.

Caves and Karst

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

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.

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.

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.