Cutting off bolts at base of roof fall at 48+50 on main line track when a piece of stone rolled off the pile & hit him in lower back causing abrasions & contusion at tailbone area. Injury occurred 8/12/08 & he went to the hospital 8/13/09. He worked 8/14/09 & 8/15/09. After still having pain he went to ER 8/17/08 & dr put him off till 8/24/09. He started missing 8/17/09.