Nugget Sandstone

Nugget Sandstone Stratigraphic range: Norian-Toarcian ~220–180 Ma PreЄ Є O S D C P T J K Pg N
Salmon-pink and white sandstones of the upper part of the Nugget Formation, Wind River Mountains, Wyoming
Type	Geological formation
Unit of	Glen Canyon Group
Underlies	Carmel Formation
Overlies	Chinle Formation
Thickness	200 m (660 ft)
Lithology
Primary	Sandstone
Other	Mudstone, siltstone
Location
Coordinates	[ ⚑ ] : 40°24′N 109°18′W / 40.4°N 109.3°W / 40.4; -109.3
Paleocoordinates	[ ⚑ ] 27°24′N 46°36′W / 27.4°N 46.6°W / 27.4; -46.6
Region	Colorado, Idaho, Utah
Country	United States
Extent	Colorado Plateau
Nugget Sandstone (the United States) Show map of the United States Nugget Sandstone (Utah) Show map of Utah

Nugget Sandstone near Red Fleet Reservoir, Uintah County, Utah. Uniform grain size and these large cross-stratification are indicative of an ancient sand dune.

Nugget Sandstone showing a bounding surface between two sets of ancient sand dunes, where wind scour eroded the top of the lower dune before the second dune advanced over it. Red Fleet Reservoir, Uintah County, Utah.

Eubrontes track in the Nugget Sandstone, Red Fleet State Park, Uintah County, Utah.

The Nugget Sandstone is a Late Triassic to Early Jurassic geologic formation that outcrops in Colorado, Idaho, Wyoming, and Utah, western United States .

In Wyoming, it is composed of a lower hematite-stained siltstone and thin-bedded sandstone. The upper part is a salmon-pink and light-gray, fine- to medium-grained cliff-forming sandstone that exhibits massive bedding to large scale cross-beds of dunes. Thickness ranges up to 86.9 m (285 feet).^[1]

Fossil theropod tracks have been reported from the formation.^[2]

Fossil content

Intermediate theropod, sphenosuchian, drepanosaurid and sphenodontian remains are known.^[3]

Other fossils

• Rhynchosauroides sp.
• Lepidosauria indet.

Ichnofossils

• Batrachopus sp.
• Brachychirotherium sp.
• Brasilichnium sp.
• Cochlichnus sp.
• Diplichnites sp.
• Grallator (Eubrontes)
• Gwyneddichnium sp.
• Octopodichnus sp.
• Otozoum sp.
• cf. Paleohelcura sp.
• Pterichnus sp.
• Scoyenia sp.
• Treptichnus sp.
• ?Acanthichnus sp.
• ?Apatopus sp.

See also

• List of pterosaur-bearing stratigraphic units
• List of dinosaur-bearing rock formations
  • List of stratigraphic units with theropod tracks

References

Bibliography

• Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN:0-520-24209-2

Further reading

• Lockley, M. G.; Tedrow, A. R.; Chamberlain, K. C.; Minter, N. J.; Lim, J.-D. (2011). "Footprints and invertebrate traces from a new site in the Nugget Sandstone (Lower Jurassic) of Idaho: implications for life in the northern reaches of the great Navajo-Nugget erg system in the western USA". Fossil Record 3. New Mexico Museum of Natural History and Science Bulletin 53: 344–356. https://econtent.unm.edu/digital/collection/bulletins/id/1425/rec/2. 
• Lockley, M. G. (2011). "Theropod- and prosauropod-dominated ichnofaunas from the Navajo-Nugget Sandstone (Lower Jurassic) at Dinosaur National Monument: implications for prosauropod behaviour and ecology". Fossil Record 3. New Mexico Museum of Natural History and Science Bulletin 53: 316–320. https://econtent.unm.edu/digital/collection/bulletins/id/1421/rec/2. 
• Lockley, M. G. (1986). "A Guide to Dinosaur Tracksites of the Colorado Plateau and American Southwest". University of Colorado at Denver Geology Department Magazine Special Issue 1: 1–56. 

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