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• lithologic change, Mesaverde Group sediments lying above the top of the B Horizon are considered <br />Williams Fork Formation equivalents. <br />The Upper Mesaverde, or Williams Fork Formation equivalent, can be further subdivided on the basis of <br />lithology and depositional origin into an additional local member of the Mesaverde Group, referred to as the <br />Upper Williams Fork. The contact between the finer grained lagoonal-paludal, carbonaceous deposits of <br />the Lower Williams Fork and the coarser grained terrestrial deposits of the Upper Williams Fork is marked <br />by thick, cliff forming lenticular sandstones. <br />Below the Mesaverde Group lies the Mancos Shale, a lower Cretaceous, saline and gypsiferous marine <br />shale with local stringers of sandstone (Pearl, 1974). This shale creates a barrier to downward movement <br />of groundwater, restricting the vertical relative to the horizontal permeability. <br />Although small, local displacements may exist in the lease area, no major faulting has been noted. <br />Sporadic production of water while exploration drilling on air, indicates the existence of secondary <br />permeability (fractures and joints) of limited areal extent. <br />II.C.1.b Soils (See also Section II.I) No detailed soil survey covering the lease area was published by the <br />U.S. Soil Conservation Service until 1982. However, a reconnaissance Order III survey had been <br />conducted and published prior to the original permit issuance (U.S. Department of Agriculture, 1966). <br />According to this survey, the soils in the lease and adjacent contiguous areas are classified as shallow, light <br />colored loamy and rocky soils of the deserts, primarily members of the Haplorthent Great Group. Soils in <br />this calcareous outwash and local wind blown deposits cap some of the mesas and upland ridges. Recent <br />alluvial deposits are of only minor extent. <br />Surface soils are light colored, indicating a lack of organic matter. Their textures range from stoney or <br />gravelly sandy looms to clay looms, depending on the composition of the primary parent material <br />(sandstone or shale, respectively). Subsoils range from sandy loam to clay. Depth to bedrock is normally <br />less than 20 inches (U.S. Department of Agriculture, 1966). <br />The U.S. Department of Agriculture (1966) indicates that the inherent erosion hazard of the soils in the <br />lease area is high, particularly in narrow valleys and swales. It is assumed that these soils can be placed <br />into hydrologic soils group B or C (depending on the primary parent material), which indicates that the <br />infiltration rate is generally moderate to slow. <br />II.C.1.c Climate (See also Section II.E) The climate of the general area is arid to semiarid and <br />continental. Table II.C-1 gives mean monthly values of temperature and precipitation at Rangely, Colorado, <br />located about 7 miles southwest of the lease area. Similar conditions exist in the lease area. Mean <br />monthly temperatures in the Rangely area range from the low teens to the low 70's. Because temperatures <br />• Permit Renewal #3 (Rev. 8/99) II.C-4 <br />