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-19- <br />The Upper Coal-Bearing {Paonia) member consists of 200 to :iUU feet of <br />yray shales; interbedded, buff-colored, lenticular sandstones; and <br />coals. The top of this member is generally considered to be capped by a <br />massive, cliff-forming sandstone. However, like the similar sandstone at <br />the top of the Lower Coal ine~nber, this sandstone is not a single <br />persistent bed. urill hole data fur both the hit. Gunnison and the <br />Somerset life-uf-mine areas show this sandstone unit to occur as several <br />lenticular sandstones at slightly different stratiyraphic hori wns. <br />Three coal horizons have been identified in the Upper Coal member; the <br />"U" (Olive r) Horizon, the "t° (Hdwk'S IVeSt) fI0r1ZUn, dnd tf10 °Y" <br />horizon. The "U" horizon occurs directly above the "massive" sandstone <br />of the Lower Coal-Bearing member and contains three seams. This horizon <br />is currently being mined in the Orchard Valley Mine, and is planned to be <br />mined at the Hawk's Nest Mine. This seam may also be mined in the future <br />at the Mt. Gunnison Kline, and in the Bear IVO. 3 Mine. The "E" horizon <br />occurs about 13U feet above the "U" horizon and contains two coal seams. <br />This horizon is currently tieing mined at the Hawk's Nest Mine and at the <br />81ue Riboon f-tine. It may be mined at the Mt. Gunnison Mine and at the <br />dear fJo. 3 Mine in the future. The "F" horizon contains two coal seams <br />and presently is only mined at the Mt. Gunnison Kline. Coal seams of the <br />"F" horizon do nut exist to the north of the iVOrth Fork in thicknesses <br />sufficient fur inininy. <br />The Barren (Undifferentiated) memoer of the blesaverde Formation consists <br />of up to I,bUU feet of terrestrial sedimentary rocks. This unit consists <br />of fine-grained, Duff-colored, lenticular sandstones; yray shales; and <br />thin lenticular coal oeds. The sandstones predominate and are highly <br />lenticular, discontinuous and of limited lateral extent in outcrop <br />(Johnson, 1948). <br />the Uhio Creek conglomerate is the upper member of the Mesaverde <br />formation and is lUU to 2UU feet thick (Johnson and,'rlay, 1y80).The <br />hlesaverde Formation is unconfornably overlain by the Tertiary Aye Rudy or <br />lJasatch Formation. This fo rnration consists of red to buff-colored <br />shales, red sandstones, and red to gray conglomerates. The sediments of <br />this formation are weathered volcanic rucks. <br />Igneous intrusive rocks exist within the North Fdrk drainage basin. A <br />diorite plug about 1,000 feet in diameter outcrops along Hubbard Creek in <br />the SE 1/4 of Section 7. Tnis may represent the erosional remnants of a <br />volcanic flow feeder. Sills have injected the Lower Coal-Bearing ineinber, <br />particularly the "8" and "C" seams. These sills consist of diorite and <br />appear to have their source to the northwest of Terror Creek. <br />