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The largest fault system in the basin is the Dudley Bluffs Graben, a feature that <br />originates near the Piceance Creek Dome (Donnell, 1961) (Figure 4-9). Other areas <br />with closely spaced faults are present along Sulfur Creek Anticline and the axis of <br />Douglas Creek Arch. For the most part, faults in the Piceance Creek Basin have <br />only minor displacements, rarely being more than 50 feet. Many faults mapped at <br />the surface apparently die out at depth before reaching the base of the Tertiary <br />section; some die out within the upper Green River Formation. <br />Fracturing is very common in the Uinta and Green River Formations. The dominant <br />basin-wide fracture orientation strikes west-northwest, parallel to normal faults such <br />as the Dudley Bluffs Graben. A secondary orientation strikes north-northeast (Smith <br />and Whitney, 1979). Many linear tributaries to Yellow Creek and Piceance Creek <br />are apparently oriented parallel to the secondary fracture set. <br />A photo-lineation study (Figure 4-10) of the Lease area was conducted to determine <br />the dominant lineation orientation. Contrary to the basin-wide orientation, the Lease <br />area has a dominant north-northeast lineation distribution. <br />Daub & Associates, Inc. Page 4-28 NSI Mine Plan 2010 Rev. <br />Printed: 7/5/2010 Section 4 Geology