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-7- The Grassy Gap Mine area is underlain by rocks of the Cretaceous aged Mesaverde group; the Iles formation and the overlying Williams Fork formation. The Iles formation is composed of a coal bearing member bounded above by the Trout Creek Sandstone and below by the Tow Creek Sandstone. The coal bearing member includes interbedded shales, sandy shales, tight sandstones, and coal. Many thin coals are present in the sequence but the major coals are the Pinnacle with its riders and the Blacksmith. The overlying Williams Fork formation is not present in the mine or directly adjacent area. The coals mined include the Pinnacle of 6 to 7 feet in thickness with an upper and lower rider each of 3.0 to 3.5 feet in thickness. The Blacksmith Coal has also been mined. It lies l00 to 150 feet below the Pinnacle complex and ranges from 3 to 5 feet in thickness. The mine site is bounded on the east and west by northerly plunging anticlines. The Fish Creek Anticline lies to the east, the Sage Creek Anticline is to the west. The basin formed is the Hayden syncline which is structurally tied with the larger Sand Wash Basin to the northwest. The Grassy Gap Mine is located in the Hayden Syncline ground water basin. Two regionally significant aquifers are present in the general area; the Tow Creek Sandstone and the Trout Creek Sandstone. There are numerous seeps located in the area emanating from landslide debris holding moisture from snowmelt. The landslide deposits are located primarily along the lower slopes to the east of Grassy Creek. These seeps are active in spring and summer and provide base flow for Grassy Creek. No springs have been identified in the area. Three soil types will be affected by mining at Grassy Gap. All are relatively deep, well drained soils and should provide an excellent substrate for revegetation. Three vegetation types (aspen, mountain shrub, and big sagebrush - grass) will be affected by the operation. The aspen type occurs primarily on the more mesic north and east facing slopes, the mountain shrub on south and west exposures, and the sagebrush - grass occurs primarily on shallow soils on ridges and fine textured soils of alluvial fans. Both mule deer and elk use the permit area during spring, summer and fall. Elk may use the permit area during some winters, but apparently not during severe winters. The permit area is privately owned grazing land, and is used primarily as summer pasture for sheep. Description of the Ooeration and Reclamation Plans Five pits have been mined out, backfilled and topsoiled to date. All previous pit disturbance areas have been less than 30 acres, with maximum pit depths of approximately 70 feet. Up to 4 coal seams have been mined in individual pits.