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Show CHAPTER XII. THE FISH LAKE PLATEAU.â€"THE A WAP A.â€"THOUSAND LAKE MOUNTAIN. Southern extension of the Wasatch monocline across Salina Canon.â€"Its bifurcation into the Sevier and Grass Valley faults.â€"Strawberry Valley.â€"Ascent of the northern slopes of Fish Lake Plateau.â€" Summit Valley.â€"Tertiary exposures.â€"Fish.Lake Plateau.â€"Its summit.â€"The great gorge and cliffs.â€"Sources of the volcanic sheets.-â€"Origin of the gorge.â€"Fish Lake.â€"Moraines.â€"Reversal of the course of the drainage.â€"Alcoves in the plateau wall.â€"Succession of beds.â€"Trachytes and dolerites.â€"Augitic andesites.â€"Location of the vents and sources of the lavas.â€"Outlet of the lake.â€" Mount Terrill.â€"Mount Marvine.â€"Origin of Summit Valley.â€"Isolation of Mount Marvine from its parent mass.â€"Moraine Valley. â€"Exposures of Tertiary beds.â€"Mount Hilgard.â€"Gilson's Crest.â€" Lavas of Mount Hilgard.â€"The Awapa.â€"Its general configuration and structure.â€"Its desolate character.â€"Great variety of rocks displayed in the Awapa.â€"Hornblendic and granitoid tra-chytes.:â€"Conglomerates.â€"Propylites.â€"Basaltic fields of ancient date.â€"Rabbit Valley.â€" Its structural origin.â€"Erosion of the lava sheets around the borders of the valley.â€"Accumulation of modern alluvial conglomerates.â€"Exposures of Tertiary beds in Rabbit Valley.â€"Thousand Lake Mountain.â€"A remnant of the grand erosion of the Plateau Province.â€"Lava Cap.â€"Underlying Tertiary.â€"Absence of the Cretaceous and unconformity of the Tertiary with the Jurassic.â€" The Water Pocket flexure and its age.â€"Jurassic sandstone.â€"Triassic beds.â€"The Shinarump and its sculptured cliff.â€"The Red Gate.â€"The separation of the mountain from the Aquarius Plateau. The third range of plateaus, including the Fish Lake, the Awapa, and the Aquarius, are not inferior in interest to those already described. Connected with them are the masses of Mounts Marvine and Hilgard with the intervening valleys. Far to the northward, in the extension of the same line, is the Wasatch Plateau, of which the structure has already been described. The great monoclinal slope which forms its western flank splits gradually into two displacements in its southward extension, one of which forms the Sevier fault, and the other, passing gradually from a monoclinal into a sharp dislocation, forms the Grass Valley fault on the eastern side of Grass Valley. The uplifting along the course of the Sevier fault has produced the Sevier Plateau. The uplifting along the other branch or Grass Valley fault has given rise to the Fish Lake table and the Awapa Plateau. 257 17 H P |