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Spring 2009 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks and South of Divide Mining Areas <br />• northern edge of this gravity - induced crack is located very close to the southern edge of the <br />MDW pad located over Longwall Panel 21 where more extensive surface cracking has been <br />observed in the massive sandstone cliffs since longwall mining occurred. It was easy to <br />determine that this was not a mining- related crack because no mining had occurred in the area. <br />The possibility of gravity- induced cracking in the rugged country above planned mining activities <br />at the West Elk Mine is a good reason to perform baseline studies of the area prior to mining so <br />that these features can be documented. <br />r 1 <br />U <br />Figure 4. Gravity- induced tension cracks located above unmined coal in the upper, massive <br />sandstone of the Ohio Creek Member of the Mesaverde Formation, (looking northwest). Joints <br />have opened up a fool or so due to gravitational stresses under little or no lateral constraint. <br />831- 032.791 Wright Water Engineers, Inc. Page 9 <br />November 2009 <br />