Until the Industrial Revolution underground mines and mine shafts were supported using wooden supports. This created a high demand for timber, for which the mines were often competing with the smelting plants. The basic support system used was called a 'square timber set support' where there were two vertical supports and one horizontal on top of them. The area above the supports was covered with wood and often filled with waste rock. The vertical and horizontal supports were joined together using different methods, depending on which direction the main pressure was coming from, the side or the ceiling. In areas of low structural stability or in areas where the rock had been disturbed by prior mining, the supports were placed right next to each other, as can be seen in the mid‐section of the Johannes mine shaft, where the rock structure had been disturbed by open air mining.
In more advanced stages of mining, wood was also used to construct fake ceilings as mining often took place on various levels, depending on where the minerals were located. The supports often had to be repaired, but once the mine had been abandoned and began to rot, and in places close to the surface or in large chambers where the rock was unstable, the mine would often collapse and cave‐in. The open pit mines and the entrance mine shafts were kept in good technical condition over a long period of time as they were used to transport mined ore and drain the groundwater.
