As the ATRS on the Shummar Pan Bolter was set, a slam of rock measuring 2'x4'x 6"" fell from between the 2 rows of roof mats and stuck the employee in the back of the head thus knocking him to the ground. 6 stitches were required for the laceration to the forehead and 5 stitches for the laceration on the pinky finger on the left hand