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600 acres of existing associated surface disturbances have been <br />identified by the Mined Land Reclamation Divisions's Inactive Mine <br />Program. <br />Topoaraphv <br />The existing environment in the general area of the Southfield Mine <br />is one of an arid, steppe highland basin. The Canon City Coal <br />Field/Basin lies in the transition zone between the foothills of <br />the Wet Mountains and the eastern Colorado plains, ranging from <br />5,500 to 8,000 feet. The area can be characterized as a high <br />plains mesa dipping gently to the east-northeast. The mesa is <br />dissected by several northeast trending ephemeral drainages. To <br />the west and southwest of the mesa are the Wet Mountains, where the <br />drainages have their headwaters. The Wet Mountain chain is fronted <br />by a series of overthrust faults which results in pre-Cambrian <br />materials unconformably overlying overturned sedimentary units. <br />Erosion of the mountains has resulted in a pediment surface within <br />the basin from 0 to 100 feet thick. The action of several <br />ephemeral and some perennial streams has cut through the pediment <br />surface exposing the coal-bearing Vermejo Formation. This easily <br />accessed coal has been extensively mined since the turn of the <br />century leaving many unreclaimed spoils and waste piles. <br />Additional information can be found in Section 2.04.3 "General Site <br />Information" of the permit application. <br />Geologv <br />Geological information is found in Sections 2.04.5 and 2.04.6, <br />pages 1 through 30 of the permit application. Below is a summary <br />of the geology for the Southfield Mine area. <br />The mine plan area is located along the east flank of the Wet <br />Mountains adjacent to the axis of the north plunging Chandler <br />Syncline. The syncline parallels the trend of the wet Mountain <br />Fault to the west. Strata on the northeast limb of the syncline <br />dip gently to the west at approximately 5 degrees. The southwest <br />limb of the syncline dips very steeply and in some cases strata on <br />this limb are overturned. Dips in the southwest limb range from 45 <br />degrees NW to 85 degrees overturned. The Wet Mountain Fault is <br />comprised of pre-Cambrian granitic rocks uncomfortably overlying <br />overturned sedimentary shales and sandstone units of the Cretaceous <br />age. Three units are of significance in the area; the Pierre <br />Shale, Trinidad Sandstone and Vermejo Formation (see Figure 3). <br />The Pierre Shale outcrops approximately 1.5 east of the mine area. <br />The shale unit consists of 3,900 feet of olive-gray clay and silt <br />layers that contain bentonite and marine fossils. It is a non-coal <br />bearing unit that exhibits very low hydraulic conductivity and thus <br />is considered to be a relatively impermeable unit. At the top of <br />13 <br />