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Show CHAPTER X. SEVIER VALLEY AND ITS ALLUVIAL CONGLOMERATES. The headwaters of Sevier Elver.â€"Upper Sevier, or Panquitch Valley.â€"Panquitch Canon.â€"Circle Valley.â€"Origin of the Sevier Valley.â€"Conglomerates.â€"Their various kinds.â€"Sources of the materials.â€"Transportation of coarse debris and the natural laws governing it.â€"Action of rivers upon transported materials.â€"Action of the sea.â€"Alluvial conglomerates.â€"Formation of alluvial cones at the openings of mountain gorges.â€"Their structure.â€"Alluvial cones now forming in the valleys of the district.â€"A comparison between the modern alluvial formations and the ancient conglomerates.â€"Identity of the process which formed both. The South Fork of the Sevier River heads in the Markagunt near its southwestern crest, the springs being scattered among the basalt fields, which cover a considerable area in that vicinity. Two fine creeks flow eastward in broad valleys, meandering down the slopes of the plateau until they meet the opposite slopes which descend from the western wall of the Paunsagunt. Here the southernmost creek (Asa's Creek) is deflected northward, and 6 miles below, Mammoth Creek joins it, the two forming the South Fork of the Sevier. Thence northward the stream flows for more than 50 miles, receiving a few insignificant tributaries, until at the foot of Circle Valley it is joined by the East Fork issuing from a mighty chasm, which cuts from top to bottom the great Sevier Plateau. Still northward it pursues its course nearly a hundred miles more, receiving one important affluent at Salina and another at Gunnison, until it suddenly springs westward at the Pavant and cuts a chasm through it; then turning south-southwest, it meanders through a forlorn desert for about 60 miles, and ends at Sevier Lake, a large, nauseous bittern of the Great Basin. The site of this lake was at a recent epoch covered by a southward extension of Lake Bonneville. It is interesting to reflect that as late as Post-Glacial time the waters which fell upon the crests of the Pink Cliffs of Southern Utah were there divided; a part to flow southward into the Grand Canon, the remainder to flow north- 211 |