Pushing down from a 30' mud highwall. Edge broke off allowing the dozer to fall landing on it's blade, then done 1 complete somersault back onto it's tracks. The back window popped out striking ee on the side of the head. He was taken to the E.R., examined, and recieved 3 stitches to the head. He was released and returned for his next scheduled shift. He was wearing his seat belt.