Early coal extraction was small-scale, the coal lying eiction working outward from a central shaft, or a technique called room and pillar in which'rooms' of coal were extracted with pillars left to support the roofs.
Early coal extraction was small-scale, the coal lying either on the surface, or very close to it. This took the form of a bell pit, the extraction working outward from a central shaft, or a technique called room and pillar in which'rooms' of coal were extracted with pillars left to support the roofs.