Miners use this term when a continuous horizontal bed of coal or rock abruptly shifts up or down. The displacement forces the mining crew to alter their tunnel grade or abandon the heading entirely to locate the continuation of the pay zone. It is a practical field term for a normal or reverse fault encountered underground.
The main seam took a ten foot jump to the roof, so we've to grade the floor up to meet it.
Also heard as
- throw
Related terms
Fault
A planar fracture in a rock volume across which there has been significant displacement.
Heave
The horizontal displacement of a rock stratum or vein caused by a geological fault.
Trouble
A geological disruption such as a fault or washout that interrupts a coal seam or ore body.
Nip-out
A geological anomaly where a coal seam thins rapidly or disappears completely.