An unplanned roof fall occurred in entry #2 between XC 35 and XC 36 of the West B off West A, off 2nd West submain off Main North. The fall was in the return entries, there was no active mining inby the fall. There were no injuries and no equipment involved. The fall measured 90' L X 18'W X 10'H. Ventilation for recovery work was disrupted. Ventilation has now been re-established.