| Colton Formation | |
|---|---|
| Stratigraphic range: Paleocene and Eocene | |
 Typical exposure of the Colton Formation | |
| Type | Formation |
| Underlies | Green River Formation |
| Overlies | North Horn Formation |
| Area | Central Utah |
| Thickness | 200–800 meters (660–2,620 ft) |
| Lithology | |
| Primary | Reddish mudstones and sandstones |
| Location | |
| Region | Utah |
| Country | United States |
| Type section | |
| Named by | P.T. Walton 1944 |
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.
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.
The only fossil described to date is a fragmentary skeleton of the aquatic bird Presbyornis recurvirostrus [4] from a lacustrine limestone.
