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Rockfall <br />Rockfall is a natural result of weathering on steep natural slopes. Rocks falling <br />from natural cliffs travel down the slope in a combination of free fall, bouncing and <br />rolling. Rockfall presents a hazard to structures and roads. USGS open file report 78- <br />12 by Walter R. Junge, defines rockfall as an area subject to rapid, intermittent, nearly <br />unpredictable rolling sliding, or free falling of detached bedrock of any size from a cliff <br />or very steep slope. Rockfall areas most commonly occur on sparsely vegetated areas <br />having jointed bedrock cliffs and are a serious hazard for residential development and <br />road construction. <br />Rockfall activity is evident thought the permit and adjacent area. The activity is <br />associated with sandstone outcrops both above and below the coal bearing zone. <br />There is potential that subsidence affects in the vicinity of outcrop will initiate rockfall in <br />the sandstone outcrops above the coal bearing zone. <br />PR -14 -18- 03/14 <br />