EMPLOYEE WAS UNLOADING 5"" X 7"" X 16' WOODEN BARS OFF OF A SUPPLY CAR AND PILING THEM ALONG THE RIB. ONE OF THE BARS ROLLED OFF THE PILE STRIKING VICTIM ON THE LEG. CAUSE OF INJURY WAS TOO HIGH OF A PILE AND UNSTABLE CONDITION. COMPLIANCE WITH RULES/REGS WAS NOT A FACTOR, PERSONNAL EQUIP NOT A FACTOR, MINER PROFIENCY A FACTOR, MINING EQUIP/SYSTEMS NOT A FACTOR.