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• Stratigraphy <br />The rocks exposed in the Hesperus area of the San Juan Basin consist of <br />the Mancos Shale, Point Lookout Sandstone, the Menefee Formation, and <br />the Cliff House Sandstone of the Mesaverde Formation. <br />Mancos Shale <br />The Mancos Shale, the oldest formation exposed in the Hesperus area, <br />comprises a sequence of dark gray to drab, locally buff marine shale, <br />2,000 to 3,000 feet thick. The shale weathers to a drab color and is <br />characterized by rolling badlands and terraces. Only the upper part of <br />the formation is exposed in the Hesperus area. <br />Mesaverde Formation <br />The Mesaverde Formation, which overlays the Mancos Shale, is divided <br />• into three members which are, in ascending order: <br />• Point Lookout Sandstone. <br />• Menefee Formation. <br />• Cliff House Sandstone. <br />Point Lookout Sandstone. The Point Lookout Sandstone is a conspicuous, <br />cliff-forming white to buff sandstone, 300 to 400 feet thick. The lower <br />part of the Member consists of thin-bedded sandstone which grades <br />downward into the Mancos Shale and upward into a massive sandstone. <br />Cross bedding is common, but is not conspicuous in the massive portion. <br />Menefee Formation. The Menefee Formation comprises a sequence of <br />interbedded shale and sandstone, approximately 350 feet thick. The <br />Formation contains several coal beds, 2 of which are persistent and <br />potentially workable over wide areas. In general, the Menefee <br />Formations thins eastward from a maximum of about 350 feet to about 150 <br />• feet. Lenses and beds of sandstone are irregularly interbedded with <br />shale. The proportion of sandstone to shale is highly variable. <br />2.04-9 <br />