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Fall 2007 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Ares <br />.7 <br />• <br />r~ - <br />,~/~'~, <br />y~ ~ r JJ <br />,t a ~ ~- <br />if , r ' i~''t r _'F'~" 1 ,n <br />r . , ~' - <br />..~~ ~, ~ <br />,_ f - <br />• '~k <br />~- ~ ~ <br />~ ' <br />~, ' ~ r , r <br />'~^w~ = ~~3~ r(j, <br />. I Iii.: ~) J ~ I ~ Ili'L'S.a~ ' <br />Figure 5. Fall 2007 photograph of a subsidence crack located on the uphill side of the drill <br />road to West Flatiron. The crack decreases in width from about 12 inches in the soil and <br />colluvium above the road cut, to a closed hairline fracture a few feet below the top of the <br />sandstone. <br />• <br />Where this crack occurs in the soil and colluvium above the exposed bedrock, it appears to he 6 <br />to 12 inches wide with a depth of as much as 12 to 24 inches. Considerable sandy material was <br />observed in and around the crack trace, suggesting heavy runoff had occurred in this area, thus <br />contributing to the erosion along this crack trace. <br />At location 1, the crack trend is approximately N70°Vl% for a distance of approximately ~0 feet <br />upslope and changes to a N55°W trend over the next 100 feet. A possible continuation of this <br />831-032.780 <br />November 2007 <br />Wright Water Engineers, Inc. <br />Page 16 <br />