A stout, square-cut piece of timber used in underground roof support. Miners stack these blocks in a cross-hatched pattern to build a wooden crib or chock that holds up the ceiling in a mined-out area. They are also driven into the undercut of a coal face to prevent the coal from dropping prematurely.
Heard on the job
Bring up a dozen nogs so we can build a chock under that bad roof joint.
Also heard as
- chock block
- cog
Related terms
Roof
The layer of rock located immediately above an underground excavation or mineral seam.
Roofstone
The specific geological rock stratum lying directly on top of a coal seam.
Stull
A heavy timber prop wedged between the hanging wall and footwall of a stope.
Timber drawer
A specialized miner tasked with safely removing wooden support props to allow the roof to collapse.