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• 2.04.6 <br />by surficial deposits. The Wasatch Formation represents terrestrial <br />sedimentation, dominated by fluvial processes, which preceded the <br />Lacustrine Green River Formation. <br />Structural Geology: The Piceance Creek Basin is a typical intermontaine <br />basin of the Rocky Mountain region in which coal bearing strata are present. <br />Bounded on the north by the Uintah Uplift, and west by the Douglas Creek <br />Arch, the basin is asymmetric with the synclinal axis trending with the Grand <br />Hogback. The main synclinal axis bifurcated southwest of Meeker, <br />Colorado, and trends northwest. The Douglas Creek Arch, south of Rangely, <br />Colorado, is characterized by extensive faulting and numerous subsidiary <br />structural flexures present throughout the basin (Johnson, 1982). Abundant <br />tertiary intrusive bodies, located in the southeastern portion, give the basin a <br />northwesterly plunge. <br />In the southwestern portion, 3 to 5 degree dips prevail while along the Grand <br />Hogback, vertical to overturned beds are not uncommon. <br />Although the Piceance Creek Basin was formed during the Larimide <br />Orogeny, recent seismic activity detected near Carbondale, Colorado, may <br />suggest the diastrophism is continuing or being reactivated. Maximum <br />structural relief, measured from the tip of the pre- Cambrian, is estimated by <br />Murray (1962) to be at least 27,000 ft. <br />Elevation of the permit area ranges from 8000 feet plus in the northwestern <br />portion to 6000 ft. near the proposed truck loadout facilities. Exposed <br />lithologies range in age from Upper Cretaceous Marcos and Mesaverde to <br />Holocene alluvial fill along the North Fork of the Gunnison River. <br />Permit and adiacent Area: Geologic structure of the eastern Permit Area Is <br />relatively simple with an attitude of N70 ° W and 3 to 5 degree dip to the <br />northeast. In the western permit area the geologic structure changes to <br />N88 to N76 ° W and a 4 to 7 degree dip to the Northeast. The structural <br />dip direction changes near Terror Creek due to faulting as shown on Map 7. <br />PR -12 IN -16 - 02/10 <br />