Onondaga Cave

Missouri Caverns

Useful Information

Location: 1 hour south of St. Louis. I-44 west to Onondaga 130 km, exit 214 (Leasburg). Turn left on ramp (Highway H), 11 km to Onondaga Cave State Park.
Open: MAR to OCT daily 9-17, last tour 16.
Tour times change depending on the season and available staffing.
Fee: Adults USD 10, Children (6-12) USD 5, Children (0-5) free, Seniors (65+) USD 8.
Groups (10+): Adults USD 5, Children (6-12) USD 4, Children (6-12) USD 2.50.
Groups must be scheduled two weeks in advance.
Classification: SpeleologyKarst cave Speleologyriver cave, Eminence and Gasconade dolomite (Ordovician, approx 450 million years old).
Light: LightIncandescent Electric Light System
Dimension: L=2.896 m, VR=52 m, T=13-15 °C, A=213 m asl.
Guided tours: L=1,610 m, VR=52 m, D=90 min, V=40,000/a [2005].
Address: Onondaga Cave, Onondaga Cave State Park, 7556 Hwy. H, Leasburg, MO 65535, Tel: +1-573-245-6600.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


1798 according to local gossip discovered by Daniel Boone.
1886 discovered by Charles Christopher.
1886-1888 exploration.
1897 opened to the public.
1940s Name changed to Onondaga Cave
1950s acquired by Lester Dill and Lyman Riley.
1982 acquired by the State Missouri, became a State Park.


Onondaga Cave has some really beautiful formations. There are helictites, cave pearls, shields, and lily pads. This cave is considered to be the most beautifully decorated cave in Missouri, and that means a lot. Especially the still ponds of dripping water are a source of extraordinary calcite crystals. The water is so still, calcite crystals form on the surface, making calcite rafts locally called calcite ice. They are swimming because of the surface tension of the water, and sink at the slightest stirring of the water. Lily pads resemble water lilys but are actually calcite crystals formed in calcite rich water on stalagmites standing in the water. Shields are, as the name says, shield-like formations and are extremely rare. They are formed by water which is transported along a thin crack by capillary forces.

Onondaga Cave formed along the Leasburg Fault, a tectonic fracture zone which marks a vertical shear. The displacement is only 17 m, but the huge amount of fractures allows the water to enter the limestone, and the huge surface of so many cracks speeds up the limestone solution. Onondaga Cave drains water from all along the fault, not just the immediate area. However, the water which is today found in the cave is not responsible for its formation. Since then the surface and with it the drainage changed completely.

The natural entrance to Onondaga Cave is low and water filled, it was never used by natives or early settlers. No remains of any usage of the cave could be found. The cave was discovered by the local Charles Christopher, when he visited the spring in 1886. With two friends, John Eaton and Mitis Horine, and a borrowed boat, he first explored the cave. The expedition took a whole day, and persuaded them to acquire the land around the cave. Some sources tell, the cave was first discovered much earlier. The legendary Daniel Boone is said to have discovered the cave as early as 1798. Actually there is no valid source hinting this may be true, so this is just local gossip.

A rather weird story happened in this cave in the early 1930s. It is a rather common story for caves, and happens all over the world. The cave extended across the boundary to the neighbouring land, and so the neighbour thought some of the income would be his. However, this time the story had some strange twists. Onondaga Cave was run by Bob Bradford. Dr. William Mook and Lee Mook leased the adjacent property. They secretly dug a tunnel into the back of Onondaga from their land, and one day they put up a barbed wire fence inside the cave, at the halfway point in the Big Room, assuming that this was the point below the boundary. Obviously Bob Bradford was not amused and an argument started and became worse until Bob Bradford headed after Lee Mook with a rifle.

A really strange encounter happened in 1934. Missouri senatorial candidate Harry S. Truman, the later president, visited the cave with his Democrat staff. At the same time a Republican party visited the other half of the cave. When they finally met at the barbed wire fence they started to argue across the demarcation line.