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I I I I I I I I I I II I I I II II I I I I Such , ~'Jqic I,azard potential is defined herein to mean avalanches, landslides, rockf"i :~, mudflows, and debris fans, unstable slopes, ground subsidence, and areas of expansive soil and rock. \-Ihile it is beyond the scope to identify the precise location of the above geologic hazards, critical areas in general terms have been noted on the study area maps. The geology of the study area consists of Paleozoic-age rocks intruded by Laramide- age igneous rocks. The surficial morphology has been modified over time by glacial and alluvial activity. 1. AVALANCHE: The Lake County Comprehensive Plan exhibit 1-3 does not depict the location of ava- lanche areas within the study area. However, it would not be unreasonable to expect that avalanches could occur within the study area. For purposes here, slopes with an average gradient of 450 to 750 are considered most prone for avalanches. The track ,gradient averages 200 to 350 whereas the runout zones may be nearly flat. In many cases the starting zone is located above the timberline while the runout zone is located on the valley floor where development may take place. Often such potential hazards are not recognized within the runout zone. It should be noted that many years may pass between avalanches and that a potential avalanche area may not be easily recognized. The following consideration should be taken into account when assessing avalanche potential on a given site. a. RenlOval of vegetation in an elongated pattern b. Grassy slopes and exposed soil and rock faces below the timberline c. Lack of branches and scars on timber d. Leaning trees e, Patches of trees lying in the same direction f. Slope profile g. Winter snow accumulation patterns and depth Avalanche Dotential may also increase as a result of logging or wildfires where 'lege. totion has been removed. Development plans should be reviewed by persons experienced with avalanches in order to determine the nature of a potential hazard prior to issu- ance of a huilding permit. Where mitigating measures can be implemented, they should be so identified. ,~'l applicant for a building permit shall show that the proposed action is either lo- cated in a site free from avalanche danger or is adequately protected by avalanche defenses or structural provisions. 2. LANDSLIDE: Within the Study Areas exist a number of locations which may be prone to landslides. These areas of unstable slopes exist in either a natural state or have been created by certain activities of man. A s'llient concern is found in those areas where exten- sive mining has been undertaken. T~e Comprehensive Plan definition of a landslide is as follows: "Landslide means those mass movements where there is a distinct surface of rupture or zone of weakness which separates the slide material from more stahle underlying mate"ial. Such slides involve most downward and outvJal'd IJIOVel:lent of a relatively dry body of rock and/or surficial ma- terial in l'esponse to gravitational stresses." ~n'y land use in a landslide area shall avoid: 3 ,.