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.
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.
The Kaiparowits Plateau covers 3,600 km2 and preserves strata located roughly 120 km east of the leading edge of the thrust front at the time of deposition.
[2] First analyzed for its coal content, the Straight Cliffs Formation was assessed by Gregory and Moore (1931)[3] and later by Peterson (1969a, 1969b)[4][5] and Vaninetti (1979).
Work done by Allen and Johnson (2010a, b, 2011)[9][10][11] in the Rogers Canyon area reassessed some of the interpretations made by Shanley and McCabe (1991)[7] and found multiple retrogradationally stacked parasequences creating overall transgressive-regressive cycles.
[5] The top of the formation is distinguished by the Calico Bed, a braided fluvial unit, named for its white and orange coloring.
[15][16][4][7][6] The overlying Drip Tank Member consists of a coarse-grained fluvial facies thought to reflect a braided river environment.
The Straight Cliffs Formation was deposited in a variety of sub- environments that varied through time as the relative sea level of the Western Interior Seaway changed.
In the southwestern region of the plateau the John Henry Member preserves ancient river systems which were carrying sediment into the basin from the uplifting Mogollon highlands and Sevier fold – thrust belt.
[15][17] On the eastern side of the Kaiparowits Plateau the John Henry Member preserves interfingered marine and coastal deposits.
Oysters are one of the most common invertebrate fossils found in the Straight Cliffs Formation and are often preserved in large shell hash beds in marginal marine parts of the section.
[8] The Tibbet Canyon Member was initially dated based a middle Turonian index fossil Inoceramus howelli which indicates the Prionocyclus hyatti ammonite zone.
[13] A variety of invertebrate fossils have been found in the John Henry Member including the ammonite Baculites codyensis and the bivalve Endocostea baltica.
[8] Analysis of foraminifera and ostracods has helped refine depositional environment interpretations for a variety of shallow marine sub-environments such as lagoons, bays, and estuaries[19][20] Vertebrate fossils have been found throughout the Straight Cliffs Formation.
[22] Recovered fossils include sharks, rays, lepisosteid fishes, crocodyliforms, and fragmentary marsupial mammal teeth.