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• characteristics of the Iles Formation can be described. The Iles Formation is continuous and <br />can be correlated over a large area. Trout Creek Sandstone, the upper member of the Iles <br />Formation, has been mapped to be 7~ feet thick. This sandstone is easily recognized and is <br />considered a marker bed for the top of the Iles formation. Trout Creek Sandstone is a white, <br />fine-grained and well sorted sandstone. It is fairly uniform in thickness in the general area. <br />Beneath the Iles Formation lies the Mancos Shale. The Mancos Shale is a marine shale with <br />thin interbeds of siltstones and limestones and is estimated to be over 5,000 feet thick in this <br />area. This shale forms the base of the regional groundwater system in the area. These shales <br />are relatively impermeable and do not store or transmit appreciable quantities of <br />groundwater. The Mancos Shale is exposed north of the permit area and is found at depth <br />beneath the permit site. <br />The permit area straddles the southern limb of the Collum Syncline. The syncline is a <br />regional structure trending in a southeast northwest direction parallel to the major geologic <br />structure of the area in the Axial Basin. The Williams Fork and the Iles Formations are <br />truncated north of the permit area and the Mancos Shale is exposed as a result of the regional <br />geologic structure. <br />Goodspring, Taylor and Wilson Creeks are tributaries to the Yampa River, a major surface <br />water feature located some distance from the mine property. Water resources on the mine <br />property are connected to the Yampa River only by surface water discharge and then only <br />during periods of infrequent snowmelts and thunderstorm events. A second major surface <br />• water feature in the area is the Williams Fork River. However, the Williams Fork River, <br />which is a tributary to the Yampa River, does not receive discharge from Wilson, Goodspring <br />or Taylor Creeks. Instead, the Williams Fork flows into the Yampa River near the town of <br />Hamilton. This location is far above the confluence of'the Yampa River with Mitk Creek, the <br />immediate receiving system of water from Goodspring, Wilson and Taylor Creeks. <br /> <br />2.04.7-2 <br />