The shaft locations in the Calumet area tend to follow lines that trend to the NE.  This is because most shafts aim to follow productive layers of rock.  The two main layers for Calumet were the C&H Conglomerate and the Osceola Amygdaloid, about 750 ft apart.  Shafts often connected with each other underground via tunnels, so there was an underground labyrinth that provided for redundant escape in crises. Shafts are expensive to sink, but they paid off by allowing more efficient ore movement and better access to mining areas. Shafts usually had headframes, which controlled the movement of rock, mining equipment, mine water and men, and were elaborate engineering design features.

Design of headframes for mines: JMC Corlette, 1907--http://openjournals.library.usyd.edu.au