While scaling the 668 Drift, he was double checking area sounding roof, he saw a piece of rock that looked loose, when he struck the rock with his bar, rock fell to the ground, he stated the rock hit him in the arm and on the foot causing a contus. to his foot. He cont. After shift went to e/r and released then followed up with co. DR. on 9-28-10 and was placed on rest. duty.