The methods used for mining coal depend upon the distance of the coal seams below the surface, and whether the seams are horizontal or tilted.
Three basic methods used for mining coal are:
This method is used when the coal seam lays several hundreds of meters below the surface, and it involves the sink seams.
Horizontal tunnels, called galleries are formed from the shaft as the coal seams are dugout.
This is the most common type of mining.
Open cast mining-
This method of mining is used when the coal seams lie near to the surface.
Adit or drift mining
This method is used to extract coal from horizontal, gently sloping seams that outcrop along the sides of valleys.
This is used in the valleys of the Appalachian coalfield, in the USA and North-East England.