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<br /> <br />(.::1 <br /> <br /> <br />',C " <br /> <br /> <br /> <br />.0" <br /> <br />. , <br /> <br /> <br />Figure 8, Gypslferous Summerville Formation near Hanksville, Utah. <br /> <br />The thickest marine shale in the succession, and one of the great <br />,contributors to the degradation of Colorado River quality, is the Late <br />Cretaceous Mancos shale and its equivalents, seen in Figure 9 near its <br />type locality. There are Mancos badlands along the Paria and at many <br />other places in the drainage basin. <br /> <br />From the area in western Colorado where the North Fork, the <br />Gunnison, and the Uncompahgre join to make the Colorado, to the <br />vicinity of Cisco in Utah, the course of the river is bordered on the north <br />by a wide badlands eroded on the outcrop area of the Mancos shale (Fig. <br />10). The shale formation is about 5,000 feet thick, and the outcrop belt <br />probably averages more than 10 miles in width. Numerous tributaries <br />. that rise in the Book Cliffs above the badlands, carry runoff across the <br />gray clays to the Colorado. West of Crescent Junction where the drainage <br />goes to the Green River, the Price River, and Saleratus Wash carry <br />Mancos shale runoff to the main stream. <br /> <br /> <br />Further south and west, the Henrys Mountain syncline has <br />preserved a wide outcrop of Mancos shale, drained to the north by <br />Sweetwater Creek, and to the south by Bullfrog Creek. The former joins <br />the Fremont, the latter goes directly to Lake Powell. Further <br />downstream an outcrop belt of Mancos surrounds the Kaiparowitz <br />Plateau. <br /> <br />','.' <br /> <br />I <br /> <br />8 <br /> <br />-,.,,-... <br /> <br /> <br />