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• July 1993 -5- 923-2515 <br />process represents a decrease in energy of deposition, alluvial fan deposits aze <br />typically coarser-grained than alluvial deposits. <br />Quaternary colluvium (Qc): Colluvium may be defined as unlithified gravity- <br />deposited material. Colluvium occurs on valley sideslopes and in valley floors <br />adjacent to sideslopes where it has not been removed by alluvial processes. <br />Colluvium was particularly apparent at the headwaters of the drainage systems. <br />On the slopes adjacent to these primazy drainages, sediment erosion is dominant <br />and little or no fluvial deposition is evident. Where sandstone outcrops occur <br />adjacent to the valley floors, colluvium may be differentiated by composition. <br />Down slope from sandstone outcrops the colluvium is typically coarser-grained <br />than the valley floor material and is essentially sand derived from weathering of <br />the adjacent bedrock. Note that comprehensive mapping of colluvial deposits was <br />beyond the scope of this study. Therefore, colluvium was only mapped where <br />present adjacent to valleys. The upslope boundaries of colluvium, as mapped on <br />Figure 1, aze not intended to imply the extent of colluvial deposits in the upslope <br />direction. Some azeas mapped as colluvium may contain minor amounts (less <br />than 10%) of residuum. <br />Quaternary landslide deposits (Qls): A landslide may be defined as the <br />perceptible downslope movement of soil and rock. One landslide was mapped in <br />the study area along Grassy Creek (sec. 34, T. 6 N., R. 87 W. and sec. 3, T.5 <br />N., R. 87 W.). The designation of landslide for this area is consistent with the <br />USGS interpretation. <br />Recent anthropogenic fill (ra): Fill placed by man that resulted in a significant <br />change in the character of the drainage system was mapped as anthropogenic fill. <br />These features include earth fill embankments placed for the construction of <br />reservoirs and lazge earthen embankments constructed for roadways that span <br />drainages. Road fill or other features which did not significantly affect the <br />character of the drainages aze not presented. <br /> <br />Golder Associates <br />