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1) Alluvium: These deposits are relatively thin (generally less than <br />. 20 feet thick), intermittant, and restricted to the immediate stream channels. <br />The alluvium is always less than 150 feet wide, except at the confluence of two <br />or more creeks, and generally less than 100 feet wide. The alluvium is <br />dominantly boulders and cobbles with minor stretches of sand, gravel, silt and <br />clay, particularly where vegetation has trapped the fine material. The extent <br />of these sediments is shown on Drawing D-5-1, but because of the narrowness of <br />the deposits, the accuracy of the alluvial contacts is limited. The extent of <br />the disturbed material within the alluvial area in the immediate mine area is <br />shown in more detail on Drawings D-4-7, D-4-8, and D-4-9. <br />2) Fans: These deposits are located at the confluence of two or more <br />streams and are basically the same as described above, except that they tend to <br />be larger in areal extent. They range in size from a few hundred square feet to <br />a few acres. However, one deposit located at the confluence of Yank, Sand, and <br />North Thompson Creeks is about 10-15 acres (Section 28) and another at the mouth <br />of Thompson Creek is 25-30 acres (Drawing Number D-3-7 ). <br />• 3) Colluvium: These sediments are restricted to the east side of the <br />reconnaissance area (Drawing D-5-1). These deposits are probably the <br />result of unconcentrated surface runoff or sheet erosion of the Mancos Shale. <br />As stated in the description of the geology, erosion of the Mancos results in <br />strike valleys, of which Jerome Park is a good example. In the case of <br />Jerome Park, the valley is essentially dry except for storm and snow runoff. <br />Field inspection of gulleys revealed about 5 to 10 feet of heterogenous soils <br />and rock fragments resting on bedrock. <br />4) Older Unconsolidated Deposits: These deposits are related to glacial <br />activity and are not connected hydrologically to the present drainages <br />(Drawing 0-5-1). <br />• <br />5-4 <br />