The sediments that formed the Blackhawk Formation originated from erosion of the Sevier Uplift in western Utah.

At this time, the Seaway was also withdrawing (regression) eastwards, but this was irregular, with occasional episodes of the sea advancing (transgression) to cover coastal lands.

[4] Swamps were probably developed on the delta plains and on the floodplain (bottomlands) adjacent to the meandering rivers, rather than in brackish-water of lagoons because of the low sulfur content of the coals.

The plant community of the swamp environment was dominated by the evergreen conifer Sequoia cuneata and a deciduous angiosperm tree Rhamnites eminens.

Other, less abundant trees include Protophyllocladus polymorpha, Moriconia cyclotoxon, Brachyphyllum squammnosum, Podozamites sp., and the angiosperms “Cissus” marginata, Platanus raynoldsii, "Cornus” praetimpressa, Dryophyllum subfalcatum, “Ficus” planicostata, and Myrtophyllum torreyii.

Other angiosperm trees also present, but in lesser abundance include Phoenocites, “Cercidophyllum” arcticum, “Ficus” laurophylla, Laurophyllum coloradensis, Manihotites georgiana, Platanus alata, Menispermites sp., and “Viburnum” antiquum; conifers were absent.

These include rare bone fossils of fishes, turtles and crocodiles in the collections of the Prehistoric Museum in Price Utah.

The most abundant vertebrate fossils are the tracks of dinosaurs, including the blunt, three-toed hadrosaurs, long, slendered toed theropods, and the short-wide, four-toed ceratopsians.

One of these elongated hadrosaur tracks was named Dinosauropodes and heralded as the footprint of the world's biggest dinosaur.

[11] The hadrosaur tracks from the Blackhawk Formation provide insights into the behavior of these dinosaurs that is not available from their skeletons.

These individuals may have been feeding,[8] thus supporting the hypothesis by Yale paleontologist John Ostrom that hadrosaurs fed on conifers.

The full size range of tracks from the coal mines indicate individuals from 0.4 m (1.25 ft.) to 16 m (52.5 ft.) and that this species spent its entire life in the swamps.

ChlorophyceaePediastrum sp.SphenopsidaEquisetum sp.PteropsidaAllantodiopsis erosa Cyathea pinnata Onoclea hebridica Osmunda hollicki Saccoloma gardneriCycadophytaNageiopsis sp.

Widdringtonites reichiiMagnoliophytaAnnona robusta Apocynophyllum giganteum Cercidiphyllum arcticum "Cissus" marginata "Cornus" praeimpressa Cyperacites sp.

Dryophyllum subfalcatum "Ficus" laurophylla "Ficus" planicostata Phoenocites imperialis Laurophyllum coloradensis Manihotites georgiana Menispermum dauricumoides Myrtophyllum torreyi Nymphaeites dawsoni Platanus alata Platanus raynoldsii Rhamnites eminens Sabalites grayanus Trapa paulula Salix proteaefolia Viburnum antiguum[4] Asterosoma Aulichnites Chondrites Gyrochorte Helminthoida Ophiomorpha Pelecypodichnus Teichichnus Terebellina Thalassinoides [4] Anomia Brachidontes Corbula Crassostrea Ursirivus Viviparus [11]