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52.04 APPLICATION FOR PERMIT FOR SDRFACE OR UNDERGROUND MINING ACTIVITIES -- <br />MINIMUM REQUIREMENTS FOR INFORMATION ON ENVIRONMENTAL RESOURCES. <br />2,04.6 Geology Description, <br />(2) (a) (Cont'd.) <br />The Eocene Wasatch Formation consists of variegated <br />mudstone and siltstone with interbedded medium gray <br />lenticular sandstone, which is locally conglomeratic <br />(Junge, 1978). Maximum thickness is reported to be ap- <br />proximately 1600 ft. (Hail, 1972), although exposures <br />are largely obscured by surficial deposits. The [da- <br />satch Formation represents terrestrial sedimentation, <br />dominated by fluvial processes, which preceded the La- <br />custrine Green River Formation. <br />Structural Geology: The Piceance Creek Basin is a typ- <br />ical intermontane basin of the Rocky Mountain region in <br />which coal bearing strata are present. Bounded on the <br />north by the Uintah Uplift, and west by the Douglas <br />Creek Arch, the basin is asymmetric with the synclinal <br />axis trending with the Grand Hogback. The main syn- <br />clinal axis bifurcates southwest of Meeker, Colorado, <br />and trends northwest. The Douglas Creek Arch, south of <br />Rangely, Colorado, is characterized by extensive fault- <br />• ing and numerous subsidiary structural flexures pres- <br />ent throughout the basin (Johnson, 1982). Abundant <br />tertiary intrusive bodies, located in the southeastern <br />portion, give the basin a northwesterly plunge. <br />In the southwestern porCion, 3 to 5 degree dips prevail <br />while along the Grand Hogback, vertical to overturned <br />beds are not uncommon. <br />Although the Piceance Creek Basin was formed during the <br />Larimide Orogeny, recent seismic activity detected near <br />Carbondale, Colorado, may suggest the diastrophism is <br />continuing or being reactivated. Maximum structural <br />relief, measured from the top of the pre-Cambrian, is <br />estimated by Murray (1962) to be at least 27,000 ft. <br />Elevation of the Permit Area ranges from 9145 fee[ plus <br />in the northwestern portion of Lease C-37210 to 5800 <br />ft. near the train loadout facilities. Exposed lithol- <br />ogies range in age from Upper Cretaceous Mancos and <br />Mesaverde to Holocene alluvial fill along the North <br />Fork of the Gunnison River. <br />Revised 08/01/84 <br />Revised 10/01/87 <br />17 <br />