About This Item
Share This Item
Increasing level of coalification causes realignment of the optical axis of vitrinite in a direction coinciding with the direction of the maximum compressive stress, either vertical load stress or the resultant of vertical load stress and lateral tectonic stress. Measurable tilting of the optical axis occurs in horizontal coal bed in Beckley, West Virginia, region coinciding with the reported occurrence of strong in-situ lateral stress in the area. The average angle of tilting is 14° in the deeper buried Beckley Seam, and 7° in the shallow Sewell Seam. The former has severe ground-control problems. The basic assumption invoked is that coal, being organic in nature, is readily deformed under relatively lower temperature and pressure conditions than the inorganic ost rocks.
End_of_Article - Last_Page 1176------------