Wind picks up that gypsum and moves it across the basin in the dune field that tourists visit today.

But beneath the dunes, and exposed in areas where erosion has stripped away the overlying material, the old lakebed remains.

And in places where the old lakebed is exposed, the footprints come to the surface.

What A Footprint Survives By

The preservation of human footprints from 23,000 years ago is not, on its face, something that seems possible.

Most organic material from that period is gone — eaten by bacteria, dissolved by groundwater, broken down by freeze-thaw cycles, scattered by wind and animals.