Roof bolting operator was putting up the outside bolt in the first pattern row. The coal rib rolled out due to the canopy resting against the rib while operating. The rib roll struck the operator against his left side of his back causing lacerations. (Entry Width 17'11"") (Rib Roll 8"" thick - 15"" wide - 20"" long) (Hole being Drilled 26"" from the rib)