EE & ANOTHER EE WERE USING A COMALONG TO PULL THE 2 RIGHT 1 RIGHT BELT BACK TOGETHER. EE WAS STANDING NEXT TO THE BELT ON THE ROADWAY SIDE OF THE BELT WAITING FOR OTHER EE TO FINISH PULLING ON THE COMEALONG ON THE OTHER SIDE OF THE BELT. A ROOF ROCK THAT MEASURED 12""X3""THICK FELL 0UT OF THE ROOF NEXT TO A ROOF BOLT STRIKING EE ON THE TOP OF HIS HARD HAT THE ROOF HEIGHT WAS ABOUT 9