EE WAS CHECKING THE CONDITION OF THE FACES ON #3UNIT AT THE TIME OF THIS INCIDENT. HE HAD JUST ARRIVED ON THE SECTION AND WAS PERFORMING HIS ON SHIFT EXAMINATION OF THE FACES. A ROCK MEASURING 8' BY 2' BY 1/2"" FELL FROM THE ROOF STRIKING HIMON THE HEAD. IT KNOCKED HIM TO THE GROUND AND LANDED ON HIS LEGS.