OPERATOR WAS ATTEMPTING TO UNROLL CONVEYOR BELTING FROM A SUSPENDED ROLL WHEN THE ROLL CAME UNHOOKED AND FELL ON HIS FOOT. THE ROLL OF BELT HAD AN ELONGATED CENTER HOLE AS IT DID NOT HAVE A CO RE. IT WAS SUSPENDED BY CHAIN AND A BAR THRU THE ROLL. AS THE BELT ROLLED IN SPUN/JUMPED SUDDENLY AND DISLODGED. THE OPERATOR'S FOOT WAS BRUISED BUT NOT BROKEN.