unit, creeping slowly into the entry until slabs developed along silt layers or other planes of weakness, Steady-state closure in inactive areas approached a constant rate of 0.42 m but closure rates as high as 7s cm/d were recorded in active areas(8 to 10 f) high experienced complete closure within 4 to 7 days(Seymour et al. 1996). Interestingly, this closure was not considered a problem by the miners because it occurred slowly and, for the most part, predictably