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• sr~ 2 , 04 . b Doc Date:1 211 112 0 01 GEOLOGY DESCRIPTION i, Local Geology: The local area is characterized by southerly dipping, sedimentary rocks, of Cretaceous age which have been deeply eroded to the North. III II The uppermost formation exposed locally is the Cliff House Formation, which is the upper member of the Mesa Verde group. It is of marine orJgin and is composed of irregular to lenticular lenses of hard, medium-to fine-grained, calcareous sandstone in soft argillaceious sandstone, mudstone and silt} shale. The top of this formation has been removed by erosion, leaving an iaverage thickness of 350 feet. The Cliff House Formation overlies the Menefee) Forma- tion. a The Menefee Formation, which is the middle member of the Mesa Verde Group is composed of a complex assemblage of cross-bedded sandstones, black shales and coal beds. Up to seven coal seams have been identified by the U.S. Geological survey. The Menefee Formation has an average local thickness of 300 feet. The Menefee overlies the Point Lookout Formation. The Point Lookout Formation, which is the basal member of the Mesa Verde Grouo, is divided into two parts, The upper member consists of thick massive beds of even-textured, medium grained sandstone. The lower member consists of thin sandstone beds with interbedded shale and grades transitional- ly into the Mancos Shale below. The Point Lookout Formation has an average local thickness of 400 feet, The Pfancos Shale, which is exposed approximately four miles North of the Blue Flame Coal Mine, is of marine origin and composed of dark gray to black shale and silty to sandy shale with small lenses of dark gray argillace- ous limestone. The Mancos Shale has an average local thuckness of 2,000 feet. The bedding of the above mentioned sedimentary rocks dip 3° to 4° in a Southerly direction, flattening to the South.