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a[? Rock Logic <br />• Consulting LLC <br />Memorandum <br />Date: 14 January 2010 <br />To: Jim Abshire <br />Joe Brinton <br />Bill Bear <br />Rock Logic Consulting <br />PO Box 544 • Cedaredge, CO 81413 <br />Phone: (435) 851-9044 • rocklogicconsulting@gmail.com <br />Brad Lindsay* Consulting Geologist <br />From: Brad Lindsay <br />Subject: Fall 2009 Subsidence Crack Mapping <br />Field Survey <br />A thorough field survey above the B8 longwall area was conducted in November 2009. The mined <br />B8 panel underlies a high east-west trending ridgeline between Dove Gulch and Sheep Corral Gulch. <br />Both north and south facing slopes of the ridge were hiked to observe visual evidence of subsidence. <br />The ridge north of Dove Gulch was observed from a distance, but was not hiked. That area is north <br />of mining activities. A GPS unit was utilized in track mode to record the path of all traverses and <br />locations of cracks observed. Each new crack was photographed and the orientation, length, <br />is width, and vertical displacement were measured. <br />Observations <br />No cracks or visible signs of subsidence were observed along the ridge top or on the south and east <br />facing slopes of the ridge. Many cracks were observed on the steep north facing slope of the ridge. <br />As noted on the attached spreadsheet, some of the cracks are wide and have large displacements. The <br />steepness of the terrain may have aided in this. Several areas of historic creep and landslides were <br />observed as well as the recent activity noted on the map and spreadsheet. The attached map shows <br />the path that was hiked, and the location, orientation, and approximate size of cracks encountered. <br />Files <br />Crack measurements and field notes are recorded in an Excel file (Subsidence Crack Mapping Fall <br />09.xls). The AutoCAD map (Subsidence-Crack-Nov09-source.dwg) was updated with the track <br />surveyed and lengths, orientations, and locations of new cracks observed. Digital photos of <br />the cracks are attached. <br />CJ