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l~ <br />GEOLOGY <br />2.04.6 (1) (a) (i) <br /> <br />The following comments are addressed to the alledged <br />"several inconsistencies" depicted on the geologic cross sections <br />and the respective drill hole logs. <br />The primary purpose for drawing cross sections through the <br />permit area is to illustrate through a simplified diagram the <br />general or representative lithologic relationships over the region. <br />These generalized relationships are important because they directly <br />relate to ground water movement, are necessary for assessment of <br />overburden chemistry and represent the geometric configuration of <br />the region to be mined. <br />With these basic premises in mind, cross sections are prepared <br />utilizing a combination of lithologic logs, geophysical logs and <br />core descriptions. Commonly, minor incremental descrepancies exist <br />between lithologic logs and electric logs. In selecting stratigraphic <br />horizons to be used on cross sections, a geologist uses a certain <br />amount of "artistic license" to generalize and simplistically <br />depict an otherwise infinitely complicated entanglement of inter- <br />finging lithologies. During this process thicker and more laterally <br />consistent lithologies are accentuated while thinner and more in- <br />consistent lithologies may be grouped into larger units and not <br />singled out. <br />The regulatory authority is specifically referred to Appendix <br />C, Page 10 which states "Because the stratigraphy within the permit <br />area is so highly interbedded and individual lithologic units are <br />lenticular, it is necessary to combine many of these units together <br />in order to better visualize lateral continuity, A generalized <br />statement of the stratigraphy in the area would be to say that the <br />sediments overlying the Sudduth Coal consist of two units. The <br />lower unit immediately above the coal consists of interbedded sand- <br />stone, sandy siltstones and mudstones, whereas the upper unit is <br />predominately 'sand free', consisting of highly interbedded shales, <br />mudstones and siltstones". Section 2,05.6(3)(b)(iv) Paqe 75 further <br />states, "The stratigraphy shown on these sections has been somewhat <br />idealized for the sake of simplicity and depicts a somewhat higher <br />lateral continuity than is actually found. Past and present exper- <br />ience in observation of lithologies in the mined areas concludes <br />that the Coalmont Formation is generally highly interbedded and <br />individual strata very lenticular in nature". <br />In the cases referred to on Page 1 and 2 of the Apparent <br />Completeness Review, the alledged "inconsistencies" on the cross- <br />sections do not constitute an inaccurate representation of the <br />geology of the permit area within the limitations of grouped lith- <br />ologies, artistic license and drafting limitations imposed by <br />minor tracing errors and map scale. <br />-1- <br />