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Subsidence Field Observations <br />West Elk Mine <br />July 22-24, 2003 <br />• Overburden depth to the B-Seam ranges from 2,050 to about 2,250 feet. <br />Location 2: <br />Point is located on top of a cliff that occurs in the uppermost massive sandstone of the Ohio <br />Creek Member of the Mesaverde Formation that forms part of the head scarp of Box Canyon. It <br />is located above un-mined longwall Pane122 in 2,000 feet of overburden. <br />• Location is about 300 feet south of the four tailgate entries of longwall Panel 22 that are <br />currently being developed eastward approximately to the drill road and traverse line. <br />• The location was selected to document pre-mine extraction landslide on the east side of Box <br />Canyon and open tension cracks on the cliff outcrops at [he head scarp (Figure 3). <br />• The landslide (Figure 4) is located above the headgate entries of un-mined longwall Panel 20. <br />• Overburden thickness (depth to B-Seam) of the landslide ranges from about 1,000 feet, at the <br />toe, to 2,100 feet at the head scarp-a vertical distance of about 1,100 feet. The maximum <br />length and width of the landslide is about 1,800 feet and 700 feet, respectively (Map 1). <br />831-032.610 Wright Water Engineers, Inc. Page 10 <br />' September 2003 <br />