LOADER DROPPED A LARGE ROCK IN BED OF TRUCK CAUSING DRIVER TO BE JOLTED HARD. EMPLOYEE COMPLAINED OF HEAD NECK AND BACK PAIN. EMPLOYEE STATED THERE WAS BLEEDING FROM THE RECTUM. EMPLOYEE LE FT AND WENT TO LOGAN GEN. HOSP. WHEN HE DISCOVERED THE BLEEDING. THE JOLT BROKE COUNTER INSIDE OF TRUCK ALSO.