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The next underlying zone, which is approximately 2-20 ft. in thickness, exhibits moderate disintegration and contains • numerous Joints and slickened sides. This zone generally has undergone moderate weathering and has become weaker, and is especially unstable in the presence of water. The third end lower moat zone has more widely spaced Joints and slickened sides. Surface moisture content end thus the degree of weathering is variable end not as extensive in this zone. This material exhibits an overall higher strength then the overlying weathered clay materials. No preferred orientations of slickened aides, Joint planes or fault plane surfaces hove been determined in the area, however, regional geological structure may suggest strike orientations of larger features (faults, etc.) in a northwest-southeast direction. Physical and chemical properties of the stratum within the overburden and interburden are found et the end of Section 4.4 Individual Laramie coal beds are often lenticular, do not extend laterally for any great distance and vary considerably in thickness. Areas £ree of coal were probably channel end channel-margin environments consisting of fine to coarse grained sandstones. Fine, well cemented sandstone boulders encountered in the Keenesburg Mine active pit are • representative of channel environments. Light gray claystones (generally massive in the Denver Basin> were deposited in well drained swamps, and light colored silts and clays deposited on levees. The coal, developed from peat layers, along with dark gray, organic rich claystones and clay-shales, accumulated in poorly drained swamps in overbank or flood bank areas. Some coal deposits may have been developed in abandoned channels. The thickest cool beds were formed in more stable parts of the swamp. The Laramie sandstone and Fox Hills sandstone (Laramie-Fox Hills aquifer) lie approximately 210 foot below the expected maximum depth of mining and should not be affected by ash disposal nctivlties. The Laramie formation overlying the Fox Hiller Sandstone consists of yellow-brown and gray to blue-gray soft carbonaceous shale and clay-shales interbedded with sand and ahaly sand. It contains cross-bedded gray to buff sandstone, which is slightly to well-cemented, and contains coal seams in the lower portion. The Laramie Forma the bedrock across all o£ the mine site and is covered by unconsolidated Tertiary and Quaternary deposits consisting of dune sand, alluvium and terrace deposits dipping slightly westward. All beds below the Tertiary and Quaternary • deposits dip slightly to the west. -10-