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_2P_ the Late Cretaceous in the general area are described below in ascending order. A stratigraphic column representing the geology of the coal member of the Mesa Yerde Formation in the permit area can be found on Map 2-10, Volume 2, and is found in this document as Figure 3. The Mancos Shale is the oldest formation exposed in the region. This unit is composed of over 4,000 feet of gray marine shales and minor interbedded buff sandstones. This unit is highly erodible and unstable. Erosion and oversteepening of slopes in this formation produce the numerous rock falls and landslides observed in the lower North Fork Drainage Basin (lunge, 19781. The Mesa Verde Formation conformably overlies the Mancos Shale. This formation consists of approximately 2,300 feet of marine and terrestrial sedimentary rocks. The Mesa Verde Formation is the coal-bearing formation in the region and is divided into four main members; the Rollins sandstone, the Lower Coal Bearing (Bowie) member, the Upper Coal Bearing (Paonia) member, and the Barren (Undifferentiated) member (Johnson, 1948). The Rollins Sandstone Member is a 120 to 300 foot thick, massive, cross-bedded, medium to fine-grained, buff to white sandstone. This sandstone is regionally extensive and resistant in outcrop and forms prrominent cliffs. This member is used regionally as a marker horizon to define the top of the Mancos Shale and the bottan of the coal-bearing horizons. The Lower Coal Bearing (Bowie) member consists of 260 to 350 feet of interbedded gray shales, thin to thick lenticular beds of buff-colored, fine- to medium-grained sandstones, and coals. The top of the member is usually capped by a massive buff-colored sandstone up to 90 feet in thickness. This sandstone, however, appears not to be a single persistent bed, but is actually several thick lenticular sandstones occurring at progressively lower stratigraphic horizons from east to west. Three coal beds exist in the Lower Coal-Bearing member; the "A" (Old King) horizon, the "B" (Somerset) horizon, and the "C" (Bear) horizon. The "A" horizon is immediately above the Rollins sandstone and is not currently mined. The "B" horizon contains two coal seams and occurs about 20 to 120 feet above the Rollins sandstone. This horizon was mined by U. S. Steel at the Sanerset Mine and may be mined at the Mt. Gunnison Mine. The "C" horizon contains one coal seam that occurs 50 to 100 feet above the "B" horizon. This horizon has been mined at U. S. Steel's Elk Creek Mine and the Bear No. 1 and 2 Mines, and is currently mined at the Bear No. 3 Mine. It may be mined at the Mt. Gunnison Mine in the future. The Upper Coal-Bearing (Paonia] member consists of 200 to 500 feet of gray shales; interbedded, buff-colored, lenticular sandstones; and coals. The top of this member usually grades into a massive, cliff-forming sandstone. However, like the similar sandstone at the top of the Lower Coal member, this sandstone is not a single persistent bed. Drill hole data for both the Mt. Gunnison and the Somerset life-of arsine areas show this sandstone unit,to occur as several lenticular sandstones at slightly different stratigraphic horizons.