The Colton Formation is a geologic formation in Utah. Its age is based on its position between the Upper Cretaceous-Paleocene North Horn Formation and overlying Green River Formation.

Colton Formation
Stratigraphic range: Paleocene and Eocene
Typical exposure of the Colton Formation
TypeFormation
UnderliesGreen River Formation
OverliesNorth Horn Formation
AreaCentral Utah
Thickness200–800 meters (660–2,620 ft)
Lithology
PrimaryReddish mudstones and sandstones
Location
RegionUtah
CountryUnited States
Type section
Named byP.T. Walton 1944

The name was first used by P.T. Walton[1] in 1944 for strata below the Green River Formation at the base of the Roan Cliffs, Utah. However, the type section was first given by E.M. Spieker in 1946.[2] for exposures near the town of Colton on Soldier Summit, Utah County, Utah. Previously, the strata were assigned to the Wasatch Formation, which had become a rather generic name by the US Geological Survey for mudstone-sandstone strata of Eocene age.

The formation is composed of reddish-brown to green beds of mudstone and shaly siltstone, interlayered with yellowish- to grayish-orange and grayish-brown, thin, fine- to medium-grained quartzose sandstone beds. The mudstones are locally variegated in shades of red and gray. Many sandstones are cross-bedded in large and small trough sets and the thicker sandstones are interpreted as deltaic deposits growing into Lake Flagstaff and Lake Uinta.[3]

Root structures and mudcracks are common in the mudstone beds.

Mudstones and sandstones of the Colton Formation at the base of the Roan Cliffs in the background.

The only fossil described to date is a fragmentary skeleton of the aquatic bird Presbyornis recurvirostrus[4] from a lacustrine limestone.

See also

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References

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  • Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.
  1. ^ Walton, P.T., 1944, Geology of the Cretaceous of the Uinta basin, Utah: Geological Society of America Bulletin, v. 55, no. 1, p. 91-130.
  2. ^ Spieker, E.M., 1946, Late Mesozoic and early Cenozoic history of central Utah, IN Shorter contributions to general geology, 1943-45: U.S. Geological Survey Professional Paper, 205-D, p. D117-D161.
  3. ^ "Utah Geological Survey Interactive Map Portal". Utah Geological Survey.
  4. ^ J. W. Hardy. 1959. A previously undescribed recurvirostrid from the Eocene of Utah. Auk 76(1):106-108 [type of Coltonia recurvirostra, now Presbyornis recurvirostrus]