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'. ,. ~ -5- _! The mine is located within the southeast portion of the Colorado Plateau. The region is characterized by broad, fairly smooth surfaced plateaus and mesas with gently dipping slopes dissected by steep canyons. Surface elevations at the mine range from a high of 5,761 feet (MSL) in the northwest part of the permit area, to a low of slightly less than 5,672 feet in the southeast part along Tuttle Draw. (See Exhibit 7-1 of the permit application and the attached Index Map) To[al topographic relief for the permit area is 95 feet. Structurally, the mine site i trending llucla Syncline. The simple fold bounded by gently the Uncompahgre Uplift on the the southwest. The coal dips 25oW. to N45oW. s located near the axis of the northwest syncline is a shallow, broad, structurally dipping flanks. The syncline lies between north and the Paradox Valley Anticline on to to 20 southwest and strikes N Minor local variations in the altitude of the coals occur due to penecontemporaneous depositional features. However, no faults have been identified within the permit area. The two coal seams being mined are the No. 1 or the Upper Dakota Coal Seam, and the No. 2 or the Lower Dakota Coal Seam. These seams lie within the "middle" Dakota litho logic unit of Cretaceous Age. The Cretaceous Dakota Formation was formed by a transgressive sea which resulted in highly variable litholoyies within the formation. Interbedded sandstones, shales and coal beds dominate the stratigraphic column as is Shown on the attached Fiyure 1, Generalized Columnar Section of the Dakota Sandstone at t1~e Nucla Mine. With the exception of unconsolidated tluaternary deposits, the only exposed formation within the permit area is the Dakota Sandstone. Geochemical analyses of each stratwn within the overburden, interhurden, and the stratum immediately below the lowest coal seam to be mined were conducted by Peabody Coal Company. Details of the chemical characteristics of the strata are presented on pages 6-16 through 6-42 of the permit application. The Nucla Mine is drained by Tuttle Draw on the south side of the permit area which is a perennial tributary of the San Miguel River. The San Miguel flows into the Dolores River and finally to the Colorado River. Stream flow in the San t4iguel River is Supported primarily by snowmelt ~nd~precipitation on upland watershed areas in the San Juan Mountains . The low land watershed areas like the Tuttle Draw Drainage Basin contribute little due to the lower precipitation. Peak flows occur during snow'nelt in late May to early June. Thunderstorms, particularly in the summer months, cause peak flows that approach snowmelt conditions. However these events are very short lived.