Fault Zone Cribbing

Here the mine tunnel crossed a fault in the rock. The diagonal line of the fault can be seen in the wall separating the grayish rock above from the brown rock below. The rock above the fault is called the "hanging wall" and the rock below the fault is called the "foot wall." This is a "normal fault" meaning that the rock of the hanging wall slid down along the fault in relation to the rock of the foot wall. Although the limestone through which this tunnel was cut is normally a very strong and stable rock, where the foot wall of the fault makes up the roof of the tunnel additional cribbing was used to prevent any potentially loose chunk of rock from falling.

Done