Straight Cliffs Formation

Straight Cliffs Formation Stratigraphic range: Late Cretaceous (Turonian to Campanian 92-81 Ma)
Type	Geological formation
Underlies	Wahweap Formation
Overlies	Tropic Shale Formation
Thickness	750 meters maximum
Location
Region	South central Utah
Country	United States
Extent	3,600 km2
Type section
Named for	Straight Cliffs
Named by	Gregory and Moore (1931)

The Straight Cliffs Formation is a stratigraphic unit in the Kaiparowits Plateau of south central Utah. It is Late Cretaceous (latest Turonian – early Campanian) in age and contains fluvial (river systems), paralic (swamps and lagoons), and marginal marine (shoreline) siliciclastic strata. It is well exposed around the margin of the Kaiparowits Plateau in the Grand Staircase – Escalante National Monument in south central Utah. The formation is named after the Straight Cliffs, a long band of cliffs creating the topographic feature Fiftymile Mountain.

The Straight Cliffs Formation was deposited in a marginal marine basin system along the western edge of the Cretaceous Western Interior Seaway. It is bounded below by the Tropic Shale and above by the Wahweap Formation. A variety of fossil species have been found within the Straight Cliffs including ammonites, mollusks, foraminifera, ostracods, sharks, fish, amphibians, turtles, lizards, crocodyliforms, dinosaurs, and mammals.