Typical Tunnel

A typical large mine tunnel. You can just make out the narrow gauge rail.

A ruined culvert near Oregon Creek, behind Old Main, the predecessor of the University of Minnesota-Duluth.

A strange sight: Part of the drain here seems to have had a skylight of glass, which has since been filled over. However, the collapsing ceiling began to create natural skylights of its own.

Heavy steel doors to isolate the underground magnetic separation mill from Eagle Mine’s main tunnel.

Some small candles light one of the few surviving tunnels that once linked buildings on the campus with the steam plant. In winter, it was common for patients to be transported through these to avoid the cold, and during the Cold War these served as nuclear fallout shelters.

A tunnel connecting the two larger caves in the hill; those that Jacob vented in the rear. The vents are still extant!

One thing that made the Eagle Mine unique is the underground mill, left of this picture. As the rocks moved down the mill, they would be turned into finer and finer powder.

One of my favorite pictures of the tunnel. I am holding a bike rim and wearing a headlamp. My friend triggered the flash just behind my lower back. The fog is a temperature inversion at the entrance of the tunnel; it was 102 degrees outside of the tunnel and about 50 degrees inside, and humid.

This is an elevator to move mine car loads of sand to the surface for cleaning and eventually glass production. Below is a flooded equipment vault. In front and behind is a loop through the larger tunnels in the mine. The horizontal braces supported electric cables for the mine carts.