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2004 Geologic Hazard Field Observations <br />South of Divide Mining Area <br />Desiccation cracks can often be recognized by their irregulaz, branching and diverging pattern- <br />less regulaz than typical subsidence cracks. Some of the lazgest desiccation cracks in the West <br />Elk mining area were observed in clays of the Barren Member of the Mesaverde Formation in the <br />Horse Gulch-Minnesota Reservoir azea where there had been no mining. The lazger, more <br />regular desiccation cracks and construction cracks may be confused with subsidence cracks in <br />azeas where mining has occurred. However, transverse and longitudinal tension cracks caused by <br />subsidence have a defmite spatial relationship to the longwall mining panel causing the cracks. <br />6.4 Pseudo Subsidence Cracks (Gravity-Induced Tension Cracks) <br />Cracks have been observed on high, steep ridges and neaz cliffs, and in landslides, in the Box <br />Canyon Lease Tract and Apache Rocks Lease Tract. The cracks look very much like subsidence <br />cracks, but they cannot be, because no mining has been done in the azea. The extensive crack on <br />a narrow ridge on West Flatiron, which was as much as 3.5 in wide and 150 feet long on August <br />27, 2002, is a good example of agravity-induced crack. It was easy to determine that this was <br />. not amining-related crack because no mining had occurred in the azea. The possibility of <br />gravity-induced cracking in the rugged county above planned mining activities at the West Elk <br />Mine is a good reason to perform baseline studies of the area prior to mining so that these <br />features can be documented. <br />`J <br />831-032.621 Wright Water Engineers, Inc. Page 11 <br />November 2004 <br />