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2.04.6 Geology Description <br />• This section of the permit application addresses information required by Section 2.04.6(3). <br />Included are descriptions of site - specific geologic conditions in the PSCM permit area and adjacent <br />areas as a basis for characterization of mining conditions, evaluation of potential mining related <br />impacts, and development of any appropriate plans for conservation of resources and control or <br />mitigation of impacts related to site geology. Additional information addressing the hydrologic <br />component of this section can be found in Section 2.04.7 of this permit application. The surface <br />geology in the PSCM permit and adjoining areas are presented on Map 2.04.6 -M1, Surface <br />Geology. <br />The information presented in this section is based on research of available published reports and <br />documents; contacts with Federal, State, and local agencies; and the results of several exploration <br />programs over the past 25 years. In reference to the geologic information presented and the <br />overburden characterization associated with addressing the feasibility of the reclamation plan it <br />should be noted that the PSCM underground facilities are located next to, and surface facilities <br />partly overlap, the Seneca II reclaimed surface mine. This surface mine has been successfully <br />reclaimed and the underground mine's surface facilities will utilize similar resources and <br />reclamation techniques as applied to the surface mine. <br />The various exploration drilling programs involved drilling and logging of numerous exploration <br />drill holes and sampling and analysis of selected core samples from these drill holes. From these <br />drill holes a subset was selected to have the drill cuttings or cores submitted for laboratory analyses <br />of over- and under - burden suitability parameters. The location of the drill holes are presented on <br />• <br />Map 2.04.6 -M2, Boreholes and Stratigraphic Cross Sections. <br />Surface mining is not proposed in this permit revision application; therefore, Subsection 2.04.6 (2) is <br />not covered under this permit application. <br />Topography <br />The topography in the PSCM permit area ranges from low- relief, gently rolling terrain to rough, <br />high- relief terrain characterized by deeply incised slopes and cliffs. Map 2.05.4 -M2, Pre PSCM <br />Topography, presents the pre -mine topography of the PSCM permit area. The form of the land <br />surface is greatly affected by the lithologic and structural setting of the local area. Easily eroded <br />shales overlying the axis of the Hayden syncline form a gently rolling terrain with very low relief. <br />The rough high - relief terrain in the permit area results from the erosion of the resistant sandstone <br />members of the Mesa Verde Group on the limbs of the Hayden Syncline. The roughest terrain of <br />this type occurs on the eastern limbs of the Fish Creek and Tow Creek anticlines (Robson & <br />Stewart, 1990). The local gradient is dependent upon the location of underlying folds. Elevations <br />range from approximately 6,600 feet amsl along Scotchmans Gulch in the northwestern part of the <br />permit area to 7,800 feet amsl at Chavez point in the northeastern part of the permit area. <br />Stratigraphy <br />Upper Cretaceous strata underlying the PSCM permit area were deposited during a five-million- <br />year time span that began approximately 70 million years ago (Berman & others, 1980). The strata <br />have undergone a long and relatively complex history of deposition followed by structural <br />deformation related to tectonic activity. This activity has impacted depositional patterns, coal <br />PSCM Permit App. 2.04 -24 6/15/09 <br />