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The Rollins Sandstone member is a 120- to 300-foot-thick, massive, cross-bedded, medium- to <br />fine-grained, buff to white sandstone. This sandstone is regionally extensive and resistant in outcrop and <br />forms prominent cliffs. This member is used regionally as a marker horizon to define the top of the <br />Mancos Shale and the bottom of the coal-bearing horizons. <br />The Lower Coal Bearing (Bowie) member consists of 260 to 350 feet of interbedded gray shales, thin to <br />thick lenticular beds of buff-colored, fine- to medium-grained sandstones, and coals. The top of the <br />member is usually capped by a massive buff-colored sandstone up to 90 feet in thickness. This sandstone, <br />however, appears not to be a single persistent bed, but is actually several thick lenticular sandstones <br />occurring at progressively lower stratigraphic horizons from east to west. <br />Three coal beds exist in the Lower Coal Bearing member - the A (Old King) horizon, the B (Somerset) <br />horizon, and the C (Bear) horizon. 'The A horizon is immediately above the Rollins sandstone and is not <br />currently mined. The B horizon contains two coal seams and occurs about 20 to 120 feet above the Rollins <br />sandstone. The C horizon contains one coal seam that occurs 50 to 100 feet above the B horizon. <br />The Upper Coal Bearing (Paonia) member consists of 200 to 500 feet of gray shales, interbedded, <br />buff-colored, lenticular sandstones, and coals. The top of this member usually grades into a massive, <br />cliff-forming sandstone. However, like the similar sandstone at the top of the Lower Coal member, this <br />sandstone is not a single persistent bed. <br />Three coal horizons have been identified in the Upper Coal member - the D (Oliver) horizon, the E <br />(Hawk's Nest) horizon, and the F horizon. The D horizon occurs directly above the "massive" sandstone of <br />the Lower Coal Bearing member and contains three seams. This horizon was mined in the Bowie No. 1 <br />Mine. The E horizon occurs about 130 feet above the D horizon and contains two coal seams. The F <br />horizon contains two coal seams. Coal seams of the F horizon do not exist to the north of the North Fork <br />of the Gunnison River in thicknesses sufficient for mining. <br />The Barren (Undifferentiated) member of the Mesaverde Formation consists of up to 1,500 feet of <br />terrestrial sedimentary rocks. This unit consists of fine-grained, buff-colored, lenticular sandstones, gray <br />shaWs and thin, lenticular coal beds. The sandstones predominate and are highly lenticular, discontinuous <br />and of limited lateral extent in outcrop. <br />The Mesaverde Formation is unconformably overlain by the Tertiary Age Rudy or Wasatch Formation. <br />This formation consists of red to buff-colored shales, red sandstones, and red to gray conglomerates. The <br />sediments of this formation are weathered volcanic rocks. The Ohio Creek conglomerate is the basal unit <br />within the formation and is 100 to 200 feet thick. <br />Tertiary igneous intrusive rocks exist within the North Fork drainage basin. A diorite plug about 1,000 <br />feet iii diameter outcrops along Hubbard Creek in the SE 1/4 of Section 7, Township 13 South, Range 91 <br />West, of the 6th P.M. This may represent the erosional remnants of a volcanic flow feeder. Sills have <br />injected the Lower Coal Bearing member, particularly the B and C seams. These sills consist of diorite and <br />appear to have their source to the northwest of Terror Creek. <br />Hydrologic Balance - Rules 2.04.5, 2.04.7, 2.05.3, 2.05.6(3), 4.05 <br />Ground Water - <br />Ground water information can be found on pages 27 to 41 of Section 2.04 and on pages 114 to 138 of <br />Section 2.05.6 of Volume 1. Water quality documentation may be found in Volume 4 and is supplemented <br />by annual hydrologic reports prepared since 1982. For a description of the ground water hydrology of the <br />13