FALL OF ROOF OR BACK at The Marion County Coal Company
Unplanned roof fall (16'x20'x12' high) discovered reportable at 310 block 9 South #7 entry. Area that fell contained multiple slips (oily slicken-sided shale and clayey rocks coated in a slick white powder) that allowed the strata to separate above the anchorage and eventually fail.
U.S. Mine Safety and Health Administration