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At the western end of the Uinta Mountains Triassic rocks rest unconformably on the Permian Park City formation. From the base upward the Triassic formations are (1) red Woodside shale, (2) marine Thaynes limestone, and (3) Ankareh redbeds. The Ankareh is overlain by the Jurassic Nugget (Navajo) sandstone. The Thaynes tongues out eastward, and east of its edge the Woodside and the Ankareh can not be differentiated.
At the eastern end of the mountains Woodside redbeds rest on the Pennsylvanian
(?) Weber sandstone. The lower part of the Woodside is the equivalent of the upper Park City (Phosphoria). The Woodside is cut by an unconformity above which lies a conglomerate. The conglomerate has been classed as the basal member of the Ankareh. The upper Ankareh consists of variegated shales and varicolored sandstones and is overlain directly by massive Nugget (Navajo) sandstone.
The erosion surface below the conglomerate, and the overlying variegated beds are readily recognized from one end of the range to the other. At the western end of the conglomerate and variegated beds were classed as the basal member of the Nugget by Boutwell (1912, 1933) and by Mathews (1931). At the eastern end these same beds were called Ankareh by Schultz (1920) and by Sears (1925). The conglomerate and variegated beds, therefore, constitute an important un-named lithologic unit which lies unconformably above the type Ankareh and below the restricted Nugget at the western end of the Uinta Mountains and unconformably above the Woodside and below the Nugget at the eastern end of the range.
The Jurassic formations of the western Uinta Mountains, from base upward are: (1) Navajo sandstone (Nugget of earlier reports), (2) Twin Creek limestone, (3) Preuss redbeds, (4) Stump sandstone, and (5) Morrison formation. Eastward along the mountains (1) the Navajo sandstone persists, (2) the Twin Creek limestone intertongues with the Carmel redbeds, (3) the Preuss redbeds grade into the cross-bedded Entrada sandstone, (4) the Stump sandstone grades into the Curtis shales and limestones, and (5) the Morrison formation thins and becomes less conglomeratic. At the west end of the mountains Belemnites occur in a sandstone (Stump) in the middle of the thick Beckwith formation of earlier reports, within 35 miles of Salt Lake City, and in the Curtis in all other sections to the east. At th eastern end of the Uintas the Curtis redbeds tongue out so that Navajo is directly overlain by Entrada, forming a single sandstone unit.
The equivalents of the Navajo, Carmel (Twin Creek), Entrada, and Curtis can be recognized in the Sundance formation of eastern Wyoming.
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