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• II.C.1 Hvdrologic Environment Several physical variables have an effect on the hydrologic <br />response of a given area. Among these are geology, soils, climate, and vegetation. Although each of <br />these subjects is covered in greater detail, in a separate portion of this application, an overview is <br />given here as an aid in understanding the hydrologic system of the coal lease and adjacent areas. <br />Individual points will be re-emphasized and strengthened, as necessary, in subsequent sections of this <br />report as data are presented and interpreted. <br />II.C.1.a Geology (See also Section II.B) The lease area lies on the southwest flank of the Red Wash <br />syncline, an asymmetrical structure on the northeast flank of the Rangely anticline. The axis of the syncline <br />trends northwesterly and lies northeast of the northern boundary of the lease area. Beds within the lease <br />area strike from northwest to southeast, with dips of about 7 degrees to the northeast near the center of the <br />lease area, to flat at the synclinal axis. Along the northern flank of the syncline, dips to as much as 70 <br />degrees are noted. <br />The axis of the Red Wash syncline trends northwest-southeast and plunges to the southeast into the much <br />larger synclinal structure of the Piceance basin (see Stose, 1935). <br />All rocks exposed in the lease area are within the 2500 to 3000-foot thick Mesaverde Group of upper <br />Cretaceous age. Stose (1935) and Cullins (1971) have further subdivided the Mesaverde Group into the <br />basal Iles Formation and the overlying Williams Fork Fonnation, with the contact lying atop the Trout Creek <br />• Sandstone member of the Iles Formation. Mapping by Cullins (1971) within the Rangely Quadrangle <br />identifies the Trout Creek Sandstone equivalent east of Douglas Creek, about three miles southeast of <br />Rangely and seven miles south of the lease area. <br />The principal coal zone within the Mesaverde Group occurs near the base of the Williams Fork Formation, <br />just above the Trout Creek Sandstone. Coals within the Iles Formation are thin and laterally discontinuous. <br />The formation lithology is dominated by laterally continuous sandstone and shales. <br />Based on this information and on data gathered during field mapping and exploratory drilling, the strata <br />exposed in the lease area have been subdivided into three members. That portion of the Mesaverde Group <br />in the lease area beneath the principal coal zone contains few, if any, significantly thick or continuous coal <br />seams. It also displays a greater abundance of coarser grain sediments (i.e., sandstones) than does the <br />overlying coal bearing interval. This sequence of rock is considered the Iles Formation equivalent. A <br />sandstone layer, which is locally referred to as the B Horizon Sandstone, is the uppermost continuous <br />sandstone in this lower portion of the Mesaverde Group and is presumably equivalent to the Trout Creek <br />Sandstone. <br />Immediately above the B Horizon, the lithology of the Mesaverde becomes notably finer grained. <br />Siltstones, mudstones, carbonaceous shales, and coal predominate, with coarser grained sediments filling <br />a secondary role as sporadically occurring, laterally discontinuous sandstones. On the basis of this <br />• Permit Renewal #3 (Rev. 8/99) II.C-3 <br />