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Unstable Ground. Ground that is moving or has moved recently. Areas of <br />• this ground occur within the lower part of the Williams Fork Formation where <br />marine shale is the predominant rock type. Characteristics on the aerial <br />photographs are typical landslide and slump features that can be confirmed on <br />the ground. Headscarps, slope scarps, hummocky ground, and related earth flow <br />features are common. <br />These areas ar•e generally well defined on the surface since they exhibit <br />typical features common to unstable ground. Areas of unstable ground are <br />mapped along the haul road alignment from about Sta. 54+00 to about Sta. 64+00. <br />In addition, two isolated landslide areas ar•e mapped along the left of the <br />alignment from about Sta. 64+00 to the end of the alignment. In these two <br />areas the characteristic land forms of unstable ground are the most pronounced <br />in the project area. <br />Stabilized Ground. Ground that appears primarily from study of aerial <br />• photographs to have experienced previous movement, but to have stabilized. <br />Areas of this ground occur in the lower part of the Williams Fork Formation. <br />These areas are covered for the most part by vegetation consisting mainly <br />of scrub oak and serviceberry. Surface examination confirmed that these areas <br />have exhibited some characteristics of unstable ground that have been modified <br />by weathering, growth of vegetation, and accumulation of humus. The most <br />noticeable characteristic observed was hummocky ground. The ground surface, <br />largely hidden from view, generally has a substantial cover of humus and <br />appears to have been modified somewhat by weathering of either the humus or <br />hummocky ground, or both. The two most prominent areas trend about N301J (see <br />Drawings 9111-1 and -2). The western of these two areas of stabilized ground <br />extends from the SE 1/4, sec. 9 across the SW 1/4, sec. 10 and into the NW 1/4, <br />• sec. 15. The eastern of these areas extends from an area of questioned <br />stabilized ground in the center SW 1/4 sec. 10 to the western part of the NW <br />11 <br />