This serial property is an unusually well-preserved and extensive epigenic gypsum karst terrain. It includes a very high density of caves: over 900 caves in a relatively small area, with over 100 km ...

The multitude of guided tours highlights some of the cave ... It was formed by a karst window—essentially, a cave roof that collapses, revealing a prehistoric underground river.

New information: IUCN, based on information provided in “Karst Conduit”, the newsletter of the International Geographical Union Commission on Man and Karst, has reported to the Centre that while the ...

Photo: Kyle Stokes/Axios Fun fact: Since opening for public tours in 1934 ... Driftless Area. Caves formed over millions of ...