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• July 1993 -7- 923-2515 <br />A lazge azea of alluvium, covering approximately 100 acres, has been mapped from upstream <br />of the confluence of Armand Draw with Scotchman's Gulch to the confluence of Scotchman's <br />Gulch with Grassy Creek. This is a broad, flat area which is partially under cultivation. An <br />alluvial fan also occurs just upstream from the confluence of Scotchman's Gulch and the <br />unnamed drainage. <br />3.2 Armand Draw <br />The headwaters of Armand Draw aze primary, ephemeral streams located in clefts between <br />hillocks. Stream gradients are steeper than the higher order reaches of the drainage. The <br />narrow channels have been mapped as undifferentiated valley fill deposits. Narrow sections of <br />the neighboring slopes have been mapped as colluvium. <br />• A small area covering approximately 4 acres downstream of the primary streams has been <br />mapped as alluvium. This azea of alluvium, located within the NEB/.NW~,4 sec. 17, T. 5 N., <br />R. 87 W., occupies a broad, relatively flat portion of the valley. It appeazs that an obstruction <br />to the channel, perhaps a more resistant bedrock outcrop, has promoted sedimentation upstream <br />of the obstruction. A narrow section of channel downstream from this small area of alluvium <br />has been mapped as undifferentiated valley fill. <br />Upstream of the Nofstger Zeigler Reservoir (NEB/. sec. 8, T. 5 N., R. 87 W.) is an azea of <br />approximately 50 acres mapped as alluvium. The stream gradient in this azea is slightly greater <br />than other areas mapped as alluvium. However, the sharp break in slope, meandering nature <br />of the stream and the broad flat valley support the alluvium designation. <br />~ - From just downstream of the reservoir to near the confluence of Armand Draw and Scotchman's <br />Gulch is a large area (approximately 100 acres) of undifferentiated valley fill. colluvium in this <br />. azea is commingled with alluvial deposits. This valley floor is irregulaz and lacks the planarity <br />which would allow differentiation of alluvium and colluvium. <br />Golder Associates <br />