Colton Formation
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. See alsoReferences
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