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• location, the syncline trends north-south and is doubly plunging to form a structural basin northwest of the proposed permit area. As shown on Ma 4, Fish Creek Ti le Geolo ~~IF° p pp gy, no serious faulting occurs except within a 2000 foot wide zone outside of the proposed permit area. Faulting within the zone is exclusively of the normal or gravity kind and occurs as horst-and-graben or step types. Displacement across the fault zone, measured in terms of stratigraphic throw, ranges from 60 to 100 feet. It is believed that the faulting occurred subsequent to the initial folding of the post-Cretaceous time during the Laramide Orogeny. The strike of the faulting is northwest- southeast. Stratigraphy The stratigraphic sequence existing in the vicinity of the Fish Creek Tipple is shown in Figure 2, General stratigraphic Column. Coal was excavated from the Wadge Seam by surface and underground mining techniques at Energy Mine No. 3. This seam lies within a series of sedimentary rocks characterized by shales, claystones, siltstones, sandstones and minor coal seams in the Upper Cretaceous Mesaverde Group. This sedimentary sequence is about 75 million years old and is composed of terrigenous clastics deposited in offshore, shallow and near-marine environments at the western adge of an epeiric seaway which was located in interior western North America during late Early Cretaceous and most of Late Cretaceous time. The sandstones were formed in beach environments and are generally fine-grained, of low porosity and are well-cemented. Some shales, most claystones and all coal seams were formed in back-barrier and near marine environments. The very thick shale formations, such as the 700-foot shale member below the Twentymile Sandstone, are offshore marine formations and are characterized by their lateral continuity, extremely fine grained nature and extremely low horizontal and • vertical permeability. 2.04-18