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3. A structure characterized by a broad, shallow basin. Fractures and dissolution <br />features are very common in rocks above the Saline Zone. <br />4. A gentle surface topography conducive to continual commercial development of <br />the property. <br />4.2. GEOLOGY OF PICEANCE CREEK BASIN <br />4.2.1. Introduction <br />The Piceance Creek Basin in northwestern Colorado (Figure 4-1) is a Laramide <br />structure that during early to middle Tertiary was the depositional site for about <br />8,000 feet of fluvial, paludal, lacustrine and saline-lacustrine sediments. These <br />sediments, which are now lithified into sandstone, siltstone, claystone, marlstone, oil <br />shale and saline minerals, represent one of the most continuous sequences of <br />Tertiary strata in the Rocky Mountain region. The middle to upper part of the <br />sequence, namely the Green River Formation, contains tremendous resources of oil <br />shale and the saline minerals halite (NaCl), nahcolite (NaHC03) and dawsonite <br />(NaAI(C03)(OH)2). Estimates have placed the total oil shale resources of the Green <br />River Formation in the Piceance Creek Basin at about 1.5 trillion barrels (Johnson <br />and others, 2009), while the total nahcolite and dawsonite resources are placed at <br />43.3 and 19 billion tons, respectively (Murray and Haun, 1974; Beard and others, <br />1974; Johnson and Keiahin, 1981; Brownfield and others, 2009). <br />The Piceance Creek Basin has been the subject of geologic study since the Hayden <br />Surveys more than 100 years ago. Most workers have focused on the stratigraphy, <br />sedimentology, mineralogy, geochemistry, resources and groundwater hydrology of <br />the Green River Formation (see bibliographic reviews by Chronic and Matsushita, <br />1974; Mullens, 1977; Laramie Energy Technology Center, 1980). General geologic <br />studies of the basin have been published by Bradley (1931, 1948, 1970), Donnell <br />(1961), Dyni (1969), Trudell and others (1970, 1974), Murray and Haun (1974), <br />Newman (1980) and Johnson and Keighin (1981), while additional descriptions of <br />Daub & Associates, Inc. Page 4-7 NSI Mine Plan 2010 Rev. <br />Printed: 7/5/2010 Section 4 Geology