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• dominated by sandstone, exhibits some facies changes, extensive lensing and interbedding among the lithological types present. Exhibit 6-3 is an overburden isopach map representing strata to be removed during mining of the Volf Creek coal seam. The Vadge coal seam is immediately above this sequence of strata. The Vadge coal seam, the principal seam to be mined, has the most continuous outcrop of any coal seam within the permit area. The outerop strikes roughly north south along the west-central portion of the permit boundary. The Vadge seam also outcrops west of an ephemeral drainage in the southern portion of the permit area in Sections 19 and 20 and northeast of Annand Draw in Section 17. The Vadge seam is typically 9 to 13 feet thick (Table 1). The Vadge seam is overlain by 50 to 60 feet of principally sandstone interbedded wish shales and siltstones. This interval of strata is very similar to that underlying the Vadge coal seam. However, the shales and siltstones appear to comprise more of the strata above than below the 4adg e. The Lennox coal seam is immediately above this sequence of strata. It is usually two to five feet thick, but has been eroded away in some areas. Exhibit 6-3 is an overburden isopach map representing strata to be removed during mining of the Vadge coal seam. • The material above the Lennox coal consists of relatively thic k sequences of shales, sandy shales, and siltstones which outcrop throughout most of the northwestern portion of the permit area. Sandstones become more prevalent toward the top of this section (Figure 2). The total thickness of these overlying beds is approximately S00 tf eat. The sandstones a re mostly fine to very fine grained, light gray, and well sorted; the shales are commonly silty with some carbonaceous material at varying depths. At the top of this sequence lie s the Twentymile sandstone member of the Williams Fork Formation, The Twentymile sandstone outcrops within the northeastern portion of the Yoast permit area, and like the Trout Creek sandstone, is a marine sandstone. The thickness of the Twentymile sandstone is 130 feet. Above the Twentymile sandstone is the upper unit of the Villiams Fork Formation. This unit, exposed within the northeast and northwest portions of the permit area, consists of sandstones, shales, and thin coals. The Lewis shale outcrops along the entire length of the north haul road corridor (Exhibit 6-1). The Lewis shale formation of Late Cretaceous age consists dominantly of dark-gray • [o bluish, homogenous marine shale. 9