Imagine that you’re a big pile of sand by the shore of Lake Michigan, between Gary and Michigan City. Your name is Mount Baldy, and you’re a popular tourist destination at what is now Indiana Dunes National Park.
For a huge pile of tiny rocks, you live a surprisingly nomadic lifestyle. More than a hundred years of tourism and foot traffic has destroyed much of the native grass that kept you stationary. You are now what they call a “wandering dune”, as wind off the lake slowly but steadily pushes your tremendous bulk a little further inland every year.
As you move, you gradually engulf everything in your path—trees, buildings, rocks, hills, your own parking lot—everything. You are an unstoppable force, like some kind of gigantic gelatinous cube, but you’re still very popular with visitors.
In 2013, you suddenly eat a child. It’s a surprising move on your part—dry quicksand isn’t supposed to be a real natural phenomenon. I mean, what is this, a 1960’s action movie?
One moment, a family from Illinois is cheerfully climbing your slopes. The next, the 6 year old boy suddenly vanishes without warning, leaving no trace. Would-be rescuers dig in the sand where he disappeared until their hands are bleeding. Geologists insist that he must have wandered off, because enormous piles sand physically cannot form hollows or pockets within themselves—but three hours later, he is found, unconscious but alive, buried almost twelve feet deep in the sand.
The current leading geological theory as to how this happened is that the organic material you engulf, like trees, slowly decompose beneath your slopes, leaving behind unstable voids held together only by the fragile remains of the decayed material. When these voids are walked over, they collapse, forming sudden sinkholes that can swallow visitors whole. The rules that typically govern stationary dunes, or wandering dunes in areas that are not forested, no longer apply to you. You are unpredictable and dangerous and have remained closed to visitors except on guided hikes ever since.