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West EIk Mrne <br />visually inspected. It was agreed by all parties present that Mountain Coai Company's contentions <br />in the alluvial valley assessment are valid, <br />Isolated alluvial deposits aze also Hound within the narrow valley of the North Fork of the Gunnison <br />River upstream from its confluence with Gribble Gulch. These deposits consist of a few isolated <br />high terraces that are largely above the t 00-year flood plain and small discontinuous islands and <br />terraces that aze within the confines of the 100-yeaz flood plan (Map 39). Unlike the East Fork of <br />Minnesota Creek, evidence of agricultural developments were only found at several isolated <br />locations, within the narrow valley of the North Fork (Map 66). The small discontinuous islands <br />and terraces are usually too small and too inegulaz in shape to support agricultural development. <br />Also, the river poses numerous difficulties for farming these locations, including access, flooding <br />and changes in channel location. <br />Soils Mapping Unit No. 27 is found on the terraces associated with the North Fork of the Gunnison <br />River. Soils of this unit are immature and exhibit no genetic soil horizontation. IvIapping Unit No. <br />400 delineates the alluvial fan deposits developed at the confluences of the various side drainages, <br />such as Sylvester Gulch, with the Nonh Fork of the Gunnison River. The only location within the <br />study area where true alluvial soils were identified (Mapping Unit No. 30U) is along the North Fork <br />of the Gunnison River, otJ'the area to be mined. This mapping unit extends downstream along the <br />south bank of the North Fork from the mouth of Lone Pine Gulch. <br />A fairly lazge alluvial fan extends from the mouth of Sylvester Gulch into the SE~la of Section 9, <br />. Tl3S, R90W. The lower portions of the fan were used by the Bear family for storage of mine <br />equipment and as their residence. Cross sections of the alluvial fan can be found in (Map 39j. As <br />can be seen, there is no evidence of terrace development. No further evaluation of this area was <br />conducted because Rule I Section 1.04.147 Rules and Regulations Colorado Mined Reclamation <br />Division defints alluvial fans as "upland areas" and as such are defined as being excluded from <br />AVF consideration. <br />The alluvial origin of the high terraces is questionable, and they may actually represent remnants of <br />glacial debris particularly in light of their relatively thin immature soils. This paint is supported in <br />light of the discussion of "upland azeas" found on page 14482, FR, Vol. 40, No. 50, Tuesday, <br />March 13, 1979, wherein U5M states: "The term 'higher terraces' in the definition is intended to <br />provide for apptopriate exclusion of geologically ancient terraces which were not formed in <br />association with the present alluvial system. This concept is consistent with that included in the <br />Alluvial Valley Floor Identification and Analysis Guidelines (43FR38039), and with Congressional <br />intent to protect only those unconsolidated stream-laid deposits which are part of a modem valley <br />floor system " These isolated high terrace areas are apparently remnants of the last glacial melt <br />period and were not formed by the current alluvial system. <br />To clarify the alluvial valley floor (AVF) (785.19(d)(3)) questions raised in Mr. Donald A. Crane's <br />{former Director of OSM's Western Technical Centerj letter of Juty 3, 1980, a discussion was held <br />with Mr. Walter C. Swain as an OSM employee. As a result, vve were advised that OSM's questions <br />were centered on the following terrace areas: <br />