A ROOF FALL WAS FOUND WHEN THE WEEKLY EXAMINER WAS WALKING THE INTAKE AIR COURSE FOR THE 1 RT 2WEST; FALL WAS IN THE BLOCK BETWEEN X CUT 268.25#7 ENTRY. IT WAS 30' X 18' X 5' HIGH; IT WAS IN AN OUTBY AREA & DID NOT AFFECT VENTILATION OR CAUSE PROPERTY DAMAGE, BUT DID BLOCK PRIMARY ES-CAPE ROUTE. THE ROUTE WAS MOVED TO #6 ENTRY; ITWAS CAUSED BY A SLIP IN THE SANDSTONE.