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West Elk Mine 1. Numerous cracks occurred in the meadow above and south of the West Elk Mine surface facilities. Some question exists as to whether these represented subsidence cracks or resulted from slight movement of the lazge landslide complex. Even if they were subsidence cracks, the cracks resulted from room-and-pillar mining, not longwall mining, as the cracks occurred above the F Seam room-and-pillaz azeas shortly after they were mined, and north of the azea of influence of longwall mining. 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-pillaz B and C Seam mining by Beaz 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 longwall panels. The cracks occur above the narrow, rigid boundary pillaz. The cracks may be the result of any or a combination of all of the above activities. According to C. R. Dunrud, these cracks aze 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 appeazed along an unimproved road south of Lone Pine Gulch neaz the center of the NWl/4 of Section 20. The cracks occurred neaz the center of the north half of the SNW longwall panel and above the western boundary of previous room-and- pillar mining of the F Seam. Cazeful study by Mr. Dunrud indicated that the most likely, but not conclusive, explanation of the cracks was that subsidence had reinitiated slight movement in old landslide deposits. 4. A limited set of cracks occurred above the barrier pillar on the east boundary of 1NW longwall panel, along the east line of Section 20. Again, this area was also affected by room-and-pillaz mining in the F Seam. 5. While mining was occurring in 8NW longwall panel, MCC received a complaint from the landowner regazding 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 summarizing their observations (CDMG, 1996). Since WWE 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 lazge, 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 19. According to Dr. Pendleton of DMG, the observed features are typical of lazge landslide masses in the Williams Fork Formation (geological equivalent of the Mesaverde Formation) and they 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 1.05-98 Revised November 1004 PRIG