The IE, a coal hauler operator, was found laying on the ground holding himself up by his left elbow. The IE was in xc 2-1 at station # 21+15, when he was struck by a rock, that fell out between the roof bolts, and struck him on top of the head. The rock measured 10'L x 3'W x 0-11"" thick, and fell from a height of 7'11"".