Mining. (See quots.)

Mining. A protrusion of sedimentary rock into the floor or roof of a coal seam, resulting in a diminished thickness of the seam. Now rare.

Coal Mining. (See quots.)

Something arched like a hog's back. Coal Mining. A sharp rise in the floor of a coal seam. Obsolete.

Coal Mining (Newcastle). ‘A portion of the roof or floor which bulges or intrudes into the coal.’