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<br />Aspen HighllJllds Ski Area. Draft Environmt!lllaJ Impacl Stale~n.t
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<br />1bis section provides a summary description of the affected environment (existing physical. biological. social,
<br />and ecooomic conditions. the eovironmeotal consequeoces of the alternatives (potential impacts to the same
<br />environment), and potential mitigation measures. Information on the affected environment was derived from field
<br />studies. review of existing reports. literature searcbes. surveys. personal interviews. agency consultations. and
<br />public comment. Only those aspects of the affected environmeot pertinent to the decisions to be made are
<br />discussed in this swnmary. The environmental consequences are based on analyses of how the alternatives would
<br />affect existing environmental conditions. Each resource area outlines poteotial mitigation measures which could
<br />be employed to minimize or avoid impacts. In addition, a Forest Plan consistency analysis was completed for
<br />each resource. where applicable. The Draft ElS contains a description of the areas of noncompliance that were
<br />not consistent with the Forest Plan. Technical reports for the major disciplines and resources of concern, as well
<br />as the Forest Plan consistency analysis are on me at the Aspen Ranger District.
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<br />GEOLOGY AND SOILS
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<br />AFFECTED ENVIRONMENT
<br />Aspen Highlands consists of a northeast sloping bedrock ridge composed of a thick sequence of sedimeotary
<br />rocks. and which is flanked by Castle Creek to the east and by Maroon Creek 10 the west. Despite the steep
<br />slopes and valleyward dip of bedding, the shape of the ridge combined with the strength of the fonnations provide
<br />considerable slope stability. Ten bedrock formations are found in Aspen Highlands. as well as 15 unconsolidated
<br />deposits. all of which are of Quaternary age and include alluvial. glacial. and mass-movement deposits.
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<br />The nine geologic hazards that present potential dangers to life or property are typical of steep mountain
<br />environments. and consist of slope instability and its erosional and depositional side effects. Almost all occur
<br />on the lower, oversteepened ridge flanks or in the vicinity of the tributary cirques and gullies in the southwest pan
<br />of the ski area. The distribution of geologic hazards in the two watersheds is swnmarized in Table 5.
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<br />Unstable and potentially WlStable slopes are due to deep-seated bedrock movements. failure of shallow soil layers.
<br />or excessive creep or erosion. During the 1994195 season. heavy snows combined with cold temperatures in
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<br />Unstable slopes
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<br /> acres % acres
<br />rock slides 138.5 20.4 t8.9
<br />debris slides 0.0 0.0 0.4
<br />erosionJrilling t5.6 2.3 0.0
<br />rock slides 97.1 14.3 40.9
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<br />Maroon Creek Castle Creek Distribution
<br />%
<br />7.4 Maroon Bow~ slop<.< of Castle Cn:ek
<br />0.2 Heads of Ist-order dminages, Castle Creek
<br />0.0 Steep ski runs
<br />16.1 Maroon Bow~ below Moment of Truth catwalk
<br />[included with rock slides] Heads of Ist-order dminages
<br />301.7 44.5 171.0 67.5 Basins fronted byalluviaJJdebris fans
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<br />Hll28fd
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<br />Potentially
<br />unstable slopes debris slidelacceL creep
<br />
<br />n-ebris-flow & debris-avalanche-prone
<br />lopes
<br />Rockfall
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<br />Gravitational spreading (Sackung)
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<br />Soil and talus creep
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<br />IOtals
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<br />124.6 18.4 12.7 5.0 Maroon Creekside of ridge, high elevation
<br />[dispersed linear features] Ridge crest between Cloud 9 and Highland Peak
<br />0.0 0.0 9.2 3.6 Isolated talus and rock glaciers, Maroon Creek
<br />677.6 100 253.2 100.0
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<br />14
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<br />Seclion III
<br />Geology and Soil,
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