There are miles of underground passageways in southeastern Minnesota that tell a story of the area long before it was a state. 

Etched into the limestone of the 400 caves in that region of the state are fossils of creatures from 450 million years ago, when Minnesota was covered by an inland sea.

MPR News host Angela Davis speaks with her guests about why that area of our state has so many caves and what makes these underground worlds wondrous. 

The show will feature two caves that are open to the public — Niagara Cave in Harmony, Minn., which has an underground waterfall and a subterranean chapel, and Mystery Cave, the longest cave in the state at 13 miles. 

Guests:

• Aaron Bishop is the manager of Niagara Cave in Harmony and his parents own the cave. His educational background is in geology.




• Ian Pringle is an interpretive naturalist with the Minnesota Department of Natural Resources. He leads tours of Mystery Cave near the historic ghost town of Forestville, Minn.




• John Ackerman is the founder of the Minnesota Cave Preserve and the Minnesota Caving Club. Both organizations aim to preserve, study and protect underground wilderness. Ackerman is a lifelong cave explorer and owns 45 caves that cover 36 miles underground. All are in southeastern Minnesota, except for one in Iowa.