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ALLUVIAL VALLEY FLOOR DETERMINATION <br />MCCLANE CANYON MINE <br />COAL MINE WASTE PILE <br />GARFIELD COUNTY, COLORADO <br />suggests it is the result of a mechanical/fluid sorting process, rather than random fill <br />transported to the site. The deposit does not extend to the east canyon wall, which would <br />make any impoundment of water incomplete. In other words, impounded water could <br />flow around the deposit to the east. Finally, the large contiguous landslide deposit west <br />of the creek and west of the highway would be too coincidental to not be associated with <br />this deposit. <br />Fan Deposits <br />The two fans in the investigation area are the result of episodic flood discharges. One <br />fan is from McClane Canyon and a second is from an unnamed drainage south of <br />McClane Canyon. Both fan deposits are younger than the older incised alluvium along <br />East Salt Creek because the fan deposits overlie the alluvium. The McClane Canyon fan <br />deposit extends from the mouth of the canyon to the edge of the active channel of East <br />Salt Creek (Figure 2). The fan deposits consist of a range of particle sizes-from silt to <br />coarse sand with angular gravel to cobbles. The fan deposits are distinguishable from the <br />alluvium by the predominance of angular clasts, apparent poor bedding, slight color <br />difference, geomorphic shape, and overlapping relationship with the alluvium (Photo 9). <br />Colluvial Deposits <br />In the area between the two fans, debris from slope wash and rock falls from the steep <br />canyon wall has accumulated on top of the older alluvium. The colluvial deposits consist <br />of large angular boulders (several feet in diameter) to sand and silt. There are no <br />organized drainages in the area of these deposits, but slope wash appears to have <br />historically concentrated along the edges of the landslide deposit on its way downhill to <br />the creek. The colluvial deposits are overlain by the younger landslide deposit, but large <br />rocks that have rolled up to the toe of the landslide deposit may be more recent. <br />Discussion <br />' The site geology indicates that East Salt Creek developed a relatively wide <br />floodplain, depositing more than 20 feet of alluvium in the geologic past. Fans from side <br />' canyons and colluvial deposits probably existed at the time, but the creek was active <br />enough to maintain a wider floodplain, eroding and removing other deposits. At some <br />5 <br />ERO <br />Resources <br />Corporation