In hardrock mining, this is a steep-sided surface pit where blasted ore falls by gravity into a network of underground raises and haulage levels for extraction. In offshore petroleum extraction, it refers to an excavation dredged into the seafloor to house wellhead equipment, keeping it safely below the scour depth of passing icebergs. Both uses rely on gravity and depth to protect or transport material.
Heard on the job
The old copper workings are dangerous because the glory hole at the top of the hill drops straight down into the main haulage drift.