The Moenave was deposited on anerosion surface on theChinle Formation following an earlyJurassic uplift andunconformity that represents about ten million years of missing sedimentation.[1] Periodic incursions of shallow seas from the north during the Jurassic flooded parts of Wyoming, Montana, and a northeast–southwest trending trough on the Utah/Idaho border.[2] The Moenave was deposited in a variety of river, lake, and flood-plain environments,[3] near the ancientLake Dixie.[1]
The oldest beds of this formation belong to the Dinosaur Canyon Member, a reddish, slope-forming rock layer with thin beds of siltstone that are interbedded with mudstone and fine sandstone.[4] The Dinosaur Canyon, with a local thickness of 140 to 375 feet (43 to 114 m), was probably laid down in slow-moving streams, ponds and large lakes.[5] Evidence for this is in cross-bedding of the sediments and large numbers of fish fossils.
The upper member of the Moenave is the pale reddish-brown with a thickness of 75 to 150 feet (23 to 46 m) and cliff-forming Springdale Sandstone.[5] It was deposited in swifter, larger, and more voluminous streams than the older Dinosaur Canyon Member.[4] Fossils of largesturgeon-like freshwaterfish have been found in the beds of the Springdale Sandstone.[4] The next member in the Moenave Formation is the thin-bedded Whitmore Point, which is made of mudstone andshale.[4] The lower red cliffs visible from the Zion Human History Museum (until 2000 the Zion Canyon Visitor Center) and theSt. George Dinosaur Discovery Site, discovered on February 26, 2000, are accessible examples of this formation.[6]
Dinosaur remains are among the fossils that have been recovered from the formation, with only one species-level taxon,Protosuchus richardsoni, based onbody fossils.
^abBiek, Robert F.; Grant C. Willis, Micheal D. Hylland, and Hellmut H. Doelling (August 2003). "Geology of Zion National Park, Utah". In Paul B. Anderson (editor). Geology of Utah's Parks and Monuments. Bryce Canyon Natural History Association and Utah Geological Association.ISBN1-882054-10-5
^abcdHarris, Ann G.; Tuttle, Esther; Tuttle, Sherwood D. (1997).Geology of National Parks (5th ed.). Iowa: Kendall/Hunt Publishing. pp. 30–42.ISBN0-7872-5353-7.
^Lucas, S. G., A. B. Heckert, J. W. Estep, and O. J. Anderson. 1997. "Stratigraphy, biostratigraphy, and sequence stratigraphy of the Upper Triassic Chinle Group, Four Corners region". pp. 81–107 in Anderson, O. J., B. Kues, and S. G. Lucas, editors.Mesozoic geology and paleontology of the Four Corners Region. New Mexico Geological Society, Socorro, NM. New Mexico Geological Society, 48th Field Conference.
Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.):The Dinosauria, 2nd ed., Berkeley: University of California Press. 861 pp. ISBN0-520-24209-2.
United States
Arizona,
Nevada and
Utah
