Many obstacles or discontinuities in coal seams, mine floors, and roofs have geologic origins. Changes in the vertical and lateral arrangement of different rock types and rock bedding are related to the manner in which the rock was deposited, and in some cases, deformed after burial. Certain geologic changes in roofs, seams, and floors can lead to coal thinning and loss of coal, as well as increased potential for roof falls. Understanding common vertical and lateral changes in rock types and bedding, and recognizing them in core and outcrop descriptions (where available), can aid in (1) planning and preparing for seam conditions, (2) developing roof-support plans to adapt to expected changes in roof conditions, and (3) preparing miners for potential or expected changes in seams, floors, and roofs so that changes can be identified as they appear and mine plans can be adjusted appropriately.

Coal-seam discontinuities are interruptions in the lateral continuity of a coal bed. Some discontinuities are also associated with weak roof conditions, but many weak roofs (and roof falls) occur without discontinuities in the underlying coal seam. Some discontinuities and weak roof conditions are common and expected as part of mining certain seams or in certain areas. Others, unfortunately, can be unexpected, but being able to identify the types and trends of certain features can help with adjusting mine operational and safety plans when these discontinuities are encountered.