Mammoth Cave National Park, KY

This cave system is aptly named, its colossal—over 400 miles of mapped caves and passages. The largest cave system in the world and it continues to bear new discoveries by the Cave Research Foundation which comes here on holidays to explore further, often spending 15 hours to pick up where they left off.  Truly dedicated spelunkers!!!  Having said all that, my first tour of the Historic Entrance was awesome—boggles the mind how theses huge caverns were formed over the millennia. What is conspicuously absent are the stalagmites and stalactites one usually thinks of in caves. That’s because a capstone of sandstone, which erodes  very slowly in water, lays on top of the limestone which is easily dissolved by water which is slightly acidic.  I posted on the Marengo Caves in Indiana which are full of formations because groundwater has found its way through cracks in the surface to enter the cave and form those beautiful formations.