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Mayo and Associates, LC <br />• <br />I~ <br /> <br />high angles to the shoreline, continually fed the shoreline with sediments. Thus, coal <br />seams aze discontinuous and have variably thickness and quality. <br />Overtime the depositional systems prograded eastwazd causing the shoreline, responsible <br />for the coal swamps, basal foreshore and shoreface sand deposits that overlie and <br />interfmger with the marine shale (i.e., Mancos Shale), to migrated eastward from the <br />Uinta Basin to the Piceance Basin. Thus, the beach and subaqueous sands in the <br />Wasatch Plateau, Books Cliffs, and Somerset Coal Field are depositionally and lazgely <br />strafigraphically equivalent but not time synchronous (Figure 3). As the shoreline <br />migrated eastwazd thick accumulations of an upward coarsening succession of marine <br />shale, mud, siltstone and subaerial sand (i.e., Mesaverde Group) were deposited on the <br />terrestrial alluvial plain from rivers sweeping across the plain. <br />Locally, river channels incised into previously deposited shale and in some instances into <br />the organic deposits. Many of these channels were subsequently filled with coazse river <br />sand. Sandstone channels aze generally isolated from each other both laterally and <br />vertically bymud-rich over bank and interfluvial rocks (Galloway and Hobday, 1983). <br />The internal structures of sandstone bodies, which may induce groundwater flow into the <br />mines, are show in Figure 4. <br />The terrestrial coal, foreshore, and marine shoreface deposits aze known as the <br />Mesaverde Group (Spieker, 1931; Johnson, 1978; Stanley and Colinson, 1979; Knowles, <br />1983; Hintze, 1993; Chan and Phaff, 1991; Franczk and Pitman, 1991; Mayo et al., 2003; <br />Evaluation of Potential Groundwater Inflows 14 <br />Associated with E Seam Mining, <br />West Elk Mine, Somerset, Colorado <br />February 24, 2004 <br />