ROCK LOADER OPERATOR WAS LOADING ROCK INTO TRUCK EE WAS IN TO BE LOADED WHEN A LARGE ROCK DROPPED OUT LANDING IN HIS EMPTY BED CAUSING THE ROCK TRUCK TO JAR HIM KNOCKING HIS HEAD INTO THE RIGH T DOOR WINDOW. THE FOLLOWING MORNING BACK OF NECCK STIFF. WENT TO HOSPITAL 2-22-01 FOR CHECKUP. RETURNED TO WORK 2-23-02. NO RESTRICTED ACTIVITY