Wind Cave

Wind Cave National Park is like two parks in one. The far reaching gentle prairie above ground, and the dark unknown below the surface. Even though 140 miles of cave have been discovered and mapped, it is anticipated there are another 1,000 to go. And it's all in One Square Mile of above ground surface area! Above I am kneeling in front of the natural entrance. This is where the cave's existence was first discovered- at least by white Europeans- I'm sure Native Americans had known of it for centuries. It felt like an air conditioner. It was blowing out at 6 mph. Some days it sucks in like a vacuum- it depends on where the pressure is higher. 

Bridget couldn't resist trying some underground photos!

This is boxwork. 95% of all that exists in the world is in this cave. Harder stone leaves a framework after the softer limestone is eaten away and eroded by carbonic acid. It looks like spider webs and honeycomb!