FALL OF ROOF OR BACK at The Marion County Coal Company
Unplanned roof fall discovered reportable on the stageloader between 57 and 58 block of the #3 entry of 4E section. Fall was 12' high, 16' wide and 30' long (approx.). Fall was caused by geologic abnormality of lower cover, beneath a surface stream valley which combined with frontal abutment stresses to cause a localized roof failure.
U.S. Mine Safety and Health Administration