EE WAS CRAWLING OVER THE FRAME OF THE PLANT CONVEYOR. WHILE HE WAS CROSSING OVER A ROCK FROM AN OPENING BETWEEN THE CENTER HOPPER AND THE WING WALL FELL HITTING HIM ON THE LEFT HAND. THE ROCK WAS ABOUT 2 1/2""ROUND AND FELL ABOUT 10'. NO REASON WHY THE ROCK FELL. HIS HAND WAS ON THE FRAME WHEN THE ROCK STRUCK HIM. THE DR. PUT A WRAP ON THE WRIST & HAND.