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Fault to the west. Strata on the northeast limb of the syncline dip gently to the west at <br />approximately 5 degrees. The southwest limb of the syncline dips very steeply and in some cases <br />strata on this limb aze overturned. Dips in the southwest limb range from 45 degrees NW to 85 <br />degrees overturned. The Wet Mountain Fault is comprised ofpre-Cambrian granitic rocks <br />uncomfortably overlying overturned sedimentary shales and sandstone units of the Cretaceous <br />age. Three units aze of significance in the azea -the Pierre Shale, the Trinidad Sandstone and the <br />Vermejo Formation (see Figure 3). <br />The Pierre Shale outcrops approximately 1.5 east of the mine azea. The shale unit consists of <br />3,400 feet of olive-gray clay and silt layers that contain bentonite and marine fossils. It is a non- <br />coal-bearing unit that exhibits very low hydraulic conductivity and thus is considered to be a <br />relatively impermeable unit. At the top of the Pierre is a sequence of thin, inter-bedded <br />sandstones and mudstones. <br />The Trinidad Sandstone, directly above the Pierre Shale, outcrops about 1.0 miles east of the <br />mine site and is composed of massive buff to yellow sandstones ranging from 40 to 90 feet in <br />thickness. The Trinidad Sandstone is indicative of a prodeltaic depositional environment. <br />The Vermejo Formation overlies the Trinidad Sandstone and is the coal-bearing unit of mining <br />interest to the Southfield operation. The Vermejo Formation consists of a complex network of <br />mudstones, siltstones, sandstones and eleven coal seams, all indicative of a vast fluvial delta and <br />plain sequence. The coals developed in the backwater swamp azeas of the river delta. The coal <br />seams of economic importance in the azea are Monazch, Red Arrow, Jack O'Lantern, Vento, <br />Manley and Rex Carbon. Total thickness for the Vermejo sequence is approximately 925 feet. <br />The coal seams mined at the Southfield Mine are two of the six principal seams present in the <br />Vermejo Formation -the Red Arrow and the Jack O'Lantern. The Red Arrow seam ranges in <br />thickness from 4 to 7 feet and is a moderate to high sulfur coal with 3 recognizable units <br />sepazated by bony layers of ash. The Jack O'Lantern seam is a low sulfur coal that ranges in <br />thickness from 4 to 8 feet and also consists of 3 recognizable units sepazated by boney ash layers. <br />The permittee has provided a complete coal, roof and floor analysis in the permit. For further <br />information refer to Section 2.04.6 of the permit. <br />Ascending upwazd on the stratigraphic column from the Vermejo Formation is the Raton <br />Formation, a unit consisting of two members- a basal sandstone and muddy-sandy layer. The <br />Raton averages 650 feet in thickness. The erosional base of this unit mazks the top of the <br />Vermejo Formation in the Southfield mine azea. There aze no coal-bearing units found in the <br />Raton, since its character indicates that a period of increased uplift and subsequent erosion in the <br />area followed that of the depositional low-energy environment found in the Vermejo. <br />Uncomfortably overlying the Raton Formation aze the sediments of the Poison Canyon <br />Formation. Similar in composition and character to the Raton, the Poison Canyon Formation is <br />coal barren and is 200 feet in thickness of alternating beds of mudstone and sandstone. <br />Covering most of the topographic ridges in the Southfield mine area aze a series of Pleistocene <br />boulder/colluviaValluvial deposits. Most of the boulders consist of gneiss, schist and sandstones <br />derived from erosion and mass wasting of the Wet Mountain uplift to the south and west. <br />Southfield Mine Permit Renewa104 15 September 10, 2004 <br />