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Geoloay <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, the Trinidad Sandstone and the Vermejo Formation (see Figure <br />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- <br />coal-bearing unit that exhibits very low hydraulic conductivity and <br />thus is considered to be a relatively impermeable unit. At the top <br />of the Pierre is a sequence of thin, inter-bedded sandstones and <br />mudstones. <br />The Trinidad Sandstone, directly above the Pierre Shale, outcrops <br />about 1.0 miles east of the mine site and is composed of massive <br />buff to yellow sandstones ranging from 40 to 90 feet in thickness. <br />The Trinidad Sandstone is indicative of a prodeltaic depositional <br />environment. <br />The Vermejo Formation overlies the Trinidad Sandstone and is the <br />coal-bearing unit of mining interest to the Southfield operation. <br />The Vermejo Formation consists of a complex network of mudstones, <br />siltstones, sandstones and eleven coal seams, all indicative of a <br />vast fluvial delta and plain sequence. The coals developed in the <br />backwater swamp areas of the river delta. The coal seams of <br />economic importance in the area are Monarch, Red Arrow, Jack <br />O'Lantern, Vento, Manley and Rex Carbon. Total thickness for the <br />Vermejo sequence is approximately 925 feet. <br />The coal seams mined at the Southfield Mine are two of the six <br />principal seams present in the Vermejo Formation - the Red Arrow <br />Southfield Mine Permit Renewal 03 <br />17 <br />