A structural break in the earth's crust where blocks of rock have slipped past one another. Faults disrupt the continuity of ore veins and coal seams, forcing miners to search for the displaced continuation of the deposit. They also create zones of crushed rock that can channel groundwater or cause severe roof instability in underground workings.
Heard on the job
The main seam pinches out against a normal fault with a ten-meter throw.
Insider tip
Miners often refer to faults colloquially as 'troubles' because of the immense operational headaches they cause when a profitable seam suddenly vanishes.