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2006 Subsidence and Geologic Field Observations <br />Box Canyon, West Flatiron, Apache Rocks, and South of Divide Mining Areas <br />4.15 Location 13 <br />Location 13 is located to observe and photograph the Hwy 133 landslides, which were described <br />in previous reports (for example, see pages 12-14 in the November 2005 Report). It is located <br />200 to 300 feet above, and north of, the North Fork, and is the same observation point used in <br />2005. The point provides a good uncluttered view of the landslides {Figures 29 through 32). <br />The Hwy 133 landslides occurred during the wet periods of the mid 1980s and 1990s. New <br />landslides, or renewed activity on old landslides, occurred after the colluvium on steep slopes <br />and old landslides were excavated for the rerouting of Hwy 133 from the north side to the south <br />side of the North Fork. <br />Landslide Located East of the Mouth of Box Canyon <br />The landslide located east of the mouth of Box Canyon reportedly occurred suddenly during a <br />period of high precipitation in the mid 1990s (Figure 29). The sound and tremor produced by <br />this event was heard and felt at the West Elk Mine office some 8,000 to 9,000 feet to the west. <br />A massive block of bedrock failed along fractures that formed basically one slip plane or zone. <br />The detached block slid and rotated southward somewhat as it slid, then came to rest. The <br />vertical orientation of the pine trees on the slump block indicate that it is oriented essentially the <br />same as it was before it failed. <br />No changes were observed in the slide since last year, except the slump scarp and other rocks <br />below appear somewhat more weathered, and also some more rocks probably have fallen from <br />the scarp (compare Figures 29 and 30). <br />831-032.750 Wright Water Engineers, Inc. Page 36 <br />December 2006 <br />