"All horizontal or subhorizontal development openings made in a mine have the generic name of drift. These are simply tunnels made in the rock, with a size and shape depending on their use—for example, haulage, ventilation, or exploration." -- Encyclopedia Brittannica This drift is at the 16 level in the Gilman mine and has been abandoned. Water dripping through the ceiling carries minerals, forming stalagtites and stalagmites.

Stalagtites in an abandoned drift in the Gilman mine at 16 level.