AN UNINTENTIONAL ROOF FALL OCCURRED AT THE 5 AND 60 X CUT OF THE EAST OFF OF THE 3RD NORTH PANELENTRY #4. THE FALL MEASURED 35' LONG BY 20' WIDE BY 6' DEEP. NO ONE WAS INJURED AND NO VENTILATI ON AND OR PASSAGE OF MEN WAS AFFECTED. FALL WAS CAUSED BY A HIDDEN SLIP OR SEPARATION.