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• very few fractures downhill in the drainage area (Lindsay 2005). Overall, under such <br />steep topographies, ground movements are controlled by surface topography and are <br />always downhill. <br />4.5 Surface fracturing <br />BRL geologic staff conducts an annual crack survey over active longwall panel areas. <br />The survey includes the location, orientation, horizontal length, and crack width. Mining- <br />induced cracks form at topographic highs over the panels, over the gateroads, and at <br />longwall boundaries. Repeated inspections show many areas without surface cracking. <br />Overall, a higher percentage of cracks are created over areas of shallow cover (less than <br />1,000 ft). Seven percent of the cracks are reported at higher topographies. <br />As illustrated in figure 9, crack orientation varies considerably. Some are near- <br />parallel with the longwall boundaries, while others are influenced by premining geologic <br />• structures including N70° E joints, N60° E normal faults, and perhaps east-west-oriented <br />strike-slip faults. Tensile cracks are generally 1 to 6 inches wide and form at an estimated <br />tensile strain level of 0.003. Monitoring indicates that cracks form in front of the face <br />and close as the surface goes from tension to relaxation. Observations also suggest <br />closing and gradual healing of cracks in soils and weathered bedrocks by natural caving <br />of crack walls, in-filling by sediments and organic material, and effects of storm events. <br />Cracks remain more noticeable in brittle sandstones. <br />4.6 Mass wasting <br />Within the Somerset basin, coal mine operators inspect and report any visual <br />changes in previously noticed landslide features, sandstone escarpments, etc. In its 2004 <br />subsidence monitoring plan, for instance, Oxbow indicated no recent movement in <br />landslide features, either naturally occurring or mining-induced, near its Sanborn Creek <br />and Elk Creek reserves (Kiger 2004). These results are in general agreement with visual <br />• inspections at BRL during 2003 and 2004 (Stover 2003, 2004). On November 19, 2003, <br />Maleki Technologies, Inc. Page 21