noting or pertaining to a means of extracting coal or other minerals in an underground mine from a continuous face, the roof before the face being supported at intervals by temporary or movable artificial supports. Cf. room-and-pillar. Found on https://www.infoplease.com/dictionary/longwall
noting or pertaining to a means of extracting coal or other minerals in an underground mine from a continuous face, the roof before the face being supported at intervals by temporary or movable artificial supports. Cf. room-and-pillar.