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Coal Basin Tract <br /> August is, 1996 <br /> INTRODUCTION <br /> Coal Basin is a east-facing drainage located on the western side of <br /> the Grand Hogback, a linear feature which extends from McClure Pass <br /> north along the west side of the White River Uplift. The hogback <br /> is a monoclinal feature composed of Cretaceous rocks that dip gent- <br /> ly to the west into the Piceance Basin. The Coal Basin anticline <br /> lies within the hogback. The anticlinal axis parallels Coal Creek <br /> and strikes N65*W. The beds dip 139SW in the area from west of the <br /> axis and to Huntsman Ridge (Collins, 1977) . The majority of the <br /> Mesaverde section is exposed in the hogback. Battlement Mesa, Roan <br /> Plateau, and Grand Mesa are several prominent features west of the <br /> hogback. The Roaring Fork Syncline, Sawatch Range Anticline, and <br /> White River Uplift are located to the east. Numerous good coking <br /> coal seams found in the Mesaverde formation were mined by Mid- <br /> Continent Coal and Coking Company for many years. <br /> The stratigraphic section includes a thick Tertiary group of fine- <br /> grained sedimentary units which overlie upper Cretaceous sandstones <br /> and shales. Below these upper Cretaceous units are lower Creta- <br /> ceous and upper Jurassic sandstones and shales. <br /> The Tertiary Wasatch and Ohio Creek formations include variegated <br /> claystone, siltstone, sandstone, and conglomerate with some lignite <br /> at the base of the Wasatch. The Mesaverde Group combines several <br /> units with economic beds of coking quality coal. The Mesaverde has <br /> been divided into two formations, Williams Fork and Iles. The <br /> Williams Fork is composed of light-brown to white sandstone, grey <br /> to black shale, and coal beds. The Iles consists of massive light- <br /> brown to white sandstone and interbedded shale with coal seams. <br /> Remnants of numerous recent debris flows can be found in the basin <br /> including a major one in 1977. A debris flow is a form of rapid <br /> mass movement composed of granular solids, water, and air (Costa <br /> and Jarrett, 1981) . These flows are capable of moving large vol- <br /> umes of rock. The 1977 flow transported boulders up to 6.5 feet in <br /> diameter. Several distinctly different rock levees can be found on <br /> the north side of Dutch Creek. The levees are of various heights <br /> and lengthes, but show clearly the magnitude of the past flows. <br /> Evidence of debris flows can be seen at the junction of Coal Creek <br /> with the Crystal River. Costa and Jarrett (1981) note that smaller <br /> and steeper basins tend ,to transport an increasing percentage of <br /> eroded material by mass-wasting means because the surficial depos- <br /> its are essentially unstable on the steep sided slopes. These <br /> deposits of poorly sorted colluvium created from exposed bedrock <br /> that is jointed, fractured, or faulted on sparsely vegetated or <br /> unvegetated side slopes above timber line become slope failures. <br /> The elevations to the west in the headwaters of Coal Basin along <br /> 2 <br />