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Wese Elk Mine 2. Cracks occurred on the point of a high ridge immediately north of the forks of Lone Pine • Gulch near the center of the south line of Section 17. Cursory surface investigation found no evidence that the cracks extended into the shales below a prominent sandstone ledge. Assessing the subsidence cause and relationships of these unique cracks is difficult. These cracks occurred along the south boundary of room-and-pillar B and C- Seam minirrg by Bear Coal Company, along the north boundary of MCC F-Seam room- and-pillaz mining and 700 feet north and east of the boundaries of MCC's B-Seam longwail panels. The cracks occur above the narrow, rigid boundary pillar. The cracks may be the result of any or a combination of all of the above circumstances. According to C. R. Dunrud, these cracks are lazger than any he saw in his previous extensive subsidence reseazch in the entire North Fork Valley. 3. In the fall of 1994, a series of cracks appeared along an unimproved road south of Lone Pine Gulch near the center of the NW 1!4 of.Section 20. The cracks occurred neaz the center of the north half of the 5NW longwall panel and above the western boundary of previous room-and-pillar mining of the F-Seam. Careful study by Messrs. Dunrud and Rold indicated that the most likely, but not conclusive, explanation of the cracks was that subsidence had reinitiated slight movement in old landslide deposiu. 4. A limited set of cracks occurred above the barrier pillaz on the east boundary of 1NW longwall panel, along the east line of Section 20. Again, this area was also affected by room-and-pillar mining in the F-Seam. 5. While mining was occurring in 8NW longwall panel, MCC received a complaint from the land owner regarding cracks on his property. As a result of the complaint, CDMG conducted an inspection of the surface cracks on the owner's property and wrote an inspection report s»mmarizing their observations (CDMG 1996). Since Wright Water Engineers was denied access to the site by the land owner, and therefore limited to low- elevation aerial reconnaissance, the discussion of the mechanism behind the formation of these cracks relies mostly on the CDMG inspection report. These cracks were observed in the vicinity of a relatively large, historic, episodically active landslide (Dames and Moore 1993). Extensive recent landsliding was observed in the SWl/4 of Section 24 in the spring of 1996. The landslide activity created numerous cracks and "graben-like extensional troughs up to ten feet wide and five feet deep." These cracks were parallel to the fall line, which is typical of the translation of the sliding debris as shown in Figure 14. According to Dr. Pendleton of CDMG, the observed features are typical of large landslide masses in the Williams Fork Formation (geological equivalent of the Mesaverde Formation) and ffiey occur prolifically throughout the North Fork Valley on slopes of varying gradient and aspect. Based on his experience in the Forth Fork Valley, Dr. Pendleton concluded that subsidence does not appear to be a significant dete*m;nant in the reactivation or initiation of landslide activity. CDMG concluded that "there is no evidence with which to definitively verify or discount a connection between subsidence of the MCC mine workings and this active landslide. " 2.t)5-1~3 RevisedJrm. 1995PR06; 1/96RN03; Revised May 7999TR89: ReviredJan. 1998PR08