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STRUCTURE OF COAL BASIN MINE AND ADJACENT AREA <br /> The Grand Hogback is a linear feature of steeply dipping <br /> sedimentary rocks of Mesozoic age running from the north <br /> western part of the state, near Meeker, down to the Marble <br /> area (Burbank, 1935) . The Grand Hogback is considered to be <br /> the western limit of the Rocky Mountain Province and the <br /> counter point to the eastward dipping hogbacks along the <br /> eastern edge of the Front Range. To the east of the Grand <br /> Hogback, the geology is complex and generally characterized <br /> by older, intruded and highly faulted Palezoic units . <br /> The Grand Hogback' is considered to be the eastern limit of <br /> the Colorado Plateau, a region characterized by a less complex <br /> geology, Mesozoic and younger bedrock units , and broad regional <br /> plateaus and mesas . The steeply dipping Dakota sandstone and <br /> older units in the hogback just east of the mine area are <br /> covered by a thick sequence of younger sedimentary units and <br /> do not emerge at the ground surface until the Uncompahgre <br /> Uplift southwest of Grand Junction (Burbank, 1935) . The <br /> sequence of younger sedimentary rocks overlying these units <br /> form the Piceance Basin (Tweto , 1978) . <br /> The Coal Basin Anticline occurs as a small spur near the <br /> southern end of the Grand Hogback and is confined in outcrop to <br /> the Mancos shale, Mesaverde formation, and, to a lesser extent , <br /> the Wasatch and Ohio Creek Conglomerate . These units are tilted <br /> over the buried intrusive body near the center of the <br /> anticline and dip to the north, west and south around the <br /> 11 <br />