1. The shop area of the mine near the service elevators is brightly lit and shored up with steel girders.

2. But looking the other way down the corridor, it becomes clear that vast sections of the mine live in darkness.

3. Shawn Wilczynski (left) talks with 90.3 WCPN® Audio Engineer Jeff Carlton while we wait for transport. Shawn is a mining engineer with Cargill's Cleveland mine.

4. Up close, the walls of the main part of the mine look like the view through an electron microscope. The salt walls are actually ocvered with years of accumulated salt dust.