Laserfiche WebLink
• 3.5 SITE GEOLOGIC DESCRIPTION <br />3.5.1 Mine <br />The geology of the mine site and adjacent areas is typical of the <br />regional geology. Rocks dip westerly into the Piceance Basin, with <br />only minor interruptions by north-south to northwest-southeast <br />trending folds. Faulting is minor, limited to sma]1-displacement nor- <br />mal faults (Drawing D-3-7). <br />The stratigraphy of the mine area includes formations ranging in age <br />from Pennsylvanian through Cretaceous (Drawing D-3-7). <br />Unconsolidated deposits include (1) older gravels (Pleistocene and/or <br />Pliocene) which are restricted to the tops of ridges, (2) landslide <br />material (Pleistocene and Holocene), (3) colluvium (Holocene), and <br />• (4) alluvium (Holocene). Colluvial sediments are restricted to the <br />east side of the reconnaisance area (Drawing D-3-8). These deposits <br />are probably the result of unconcentrated surface runoff or sheet <br />erosion of the Mancos Shale. The alluvium is thin and intermittent <br />and restricted to the immediate stream channels (Drawing D-3-7). The <br />most extensive alluvium is associated with fans which develop at the <br />confluences of two or more streams. The largest alluvial deposit <br />mapped in the mine area is between 10 and 15 acres. <br />On the Geologic Map of the Mine Area {Drawing D-3-7), a minor, unnamed <br />syncline is mapped about 2.5 miles to the southwest of the site. No <br />well data exist for this area, and the existing geologic mapping does <br />not show strikes and dips or the detailed structure. However, only <br />the Upper Member of the Williams Fork formation outcrops on the west <br />limb of the syncline, and based on the topography, the dips must be <br />flatter than near the mine site. Thus, none of the site water-bearing <br />zones outcrop in the minor syncline area. Based on the elevations and <br />i <br />3-17 <br />