The Kayenta Formation is a
geological formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...
in the
Glen Canyon Group that is spread across the
Colorado Plateau
The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area ...
province of the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...
, including northern
Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, AlÄ á¹£onak ) is a U.S. state, state in the Southwestern United States. It is the list of U.S. states and territories by area, 6th largest and the list of U.S. states and territories by population, 14 ...
, northwest
Colorado
Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...
,
Nevada
Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
, and
Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...
. Traditionally has been suggested as
Sinemurian
In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian an ...
-Pliensbachian, but more recent
dating of detrital zircons has yielded a depositional age of 183.7 ± 2.7 Ma, thus a Pliensbachian-
Toarcian
The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.1 Ma. It follows the Pliensbachian and is followed by the Aalenian.
The Toarc ...
age is more likely
A previous depth work recovered a solid Lower-Middle Pliensbachian age from measurements done in the
Tenney Canyon Tenney may refer to:
People
* Anne Tenney, actress
* Asa Wentworth Tenney, federal judge
* Charles Daniel Tenney, American educator and diplomat to China
* Charles H. Tenney, "City Father" in Methuen, Massachusetts; hat merchant and banker, New Yo ...
.
[
This rock formation is particularly prominent in southeastern Utah, where it is seen in the main attractions of a number of national parks and monuments. These include ]Zion National Park
Zion National Park is an American national park located in southwestern Utah near the town of Springdale. Located at the junction of the Colorado Plateau, Great Basin, and Mojave Desert regions, the park has a unique geography and a variety o ...
, Capitol Reef National Park
Capitol Reef National Park is an American national park in south-central Utah. The park is approximately long on its northsouth axis and just wide on average. The park was established in 1971 to preserve of desert landscape and is open all ye ...
, the San Rafael Swell
The San Rafael Swell is a large geologic feature located in south-central Utah, United States about west of Green River. The San Rafael Swell, measuring approximately , consists of a giant dome-shaped anticline of sandstone, shale, and limest ...
, and Canyonlands National Park
Canyonlands National Park is an American national park located in southeastern Utah near the town of Moab. The park preserves a colorful landscape eroded into numerous canyons, mesas, and buttes by the Colorado River, the Green River, and their ...
.
The Kayenta Formation frequently appears as a thinner dark broken layer below Navajo Sandstone
The Navajo Sandstone is a geological formation in the Glen Canyon Group that is spread across the U.S. states of southern Nevada, northern Arizona, northwest Colorado, and Utah as part of the Colorado Plateau province of the United States.Anonym ...
and above Wingate Sandstone (all three formations are in the same group). Together, these three formations can result in immense vertical cliffs of or more. Kayenta layers are typically red to brown in color, forming broken ledges.
Kayenta Formation in Utah
Southeast Utah
In most sections that include all three geologic formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
s of the Glen Canyon group the Kayenta is easily recognized. Even at a distance it appears as a dark-red, maroon, or lavender band of thin-bedded material between two thick, massive, cross bedded strata
In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as e ...
of buff, tan, or light-red color. Its position is also generally marked by a topographic break. Its weak beds form a bench or platform developed by stripping the Navajo sandstone back from the face of the Wingate cliffs. The Kayenta is made up of beds of sandstone, shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...
, and limestone, all lenticular
Lenticular is an adjective often relating to lenses. It may refer to:
* A term used with two meanings in botany: see
* Lenticular cloud, a lens-shaped cloud
* Lenticular galaxy, a lens-shaped galaxy
* Lenticular (geology), adjective describing a ...
, uneven at their tops, and discontinuous within short distances. They suggest deposits made by shifting streams of fluctuating volume. The sandstone beds, from less than to more than thick, are composed of relatively coarse, well-rounded quartz
Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...
grains cemented by lime and iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
. The thicker beds are indefinitely cross bedded. The shales are essentially fine-grained
Granularity (also called graininess), the condition of existing in granules or grains, refers to the extent to which a material or system is composed of distinguishable pieces. It can either refer to the extent to which a larger entity is su ...
, very thin sandstones that include lime concretions
A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...
and balls of consolidated mud. The limestone appears as solid gray-blue beds, a few inches to a few feet thick, and as lenses of limestone conglomerate
Conglomerate or conglomeration may refer to:
* Conglomerate (company)
* Conglomerate (geology)
* Conglomerate (mathematics)
In popular culture:
* The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes
** Co ...
. Most of the limestone lenses are less than long, but two were traced for nearly and one for .
Viewed as a whole, the Kayenta is readily distinguished from the geologic formations above and below it. It is unlike them in composition, color, manner of bedding, and sedimentary history. Obviously the conditions of sedimentation changed in passing from the Wingate Sandstone formation to the Kayenta and from the Kayenta to the Navajo sandstone, but the nature and regional significance of the changes have not been determined. In some measured sections the transition from Wingate to Kayenta is gradual; the material in the basal Kayenta, beds seems to have been derived from the Wingate immediately below and redeposited with only the discordance characteristic of fluviatile sediments. But in many sections the contact between the two formations is unconformable; the basal Kayenta consists of conglomerate and lenticular sandstone that fills depressions eroded in the underlying beds. In Moqui Canyon near Red Cone Spring nearly of Kayenta limestone conglomerate rests in a long meandering valley
A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over ...
cut in Wingate. Likewise, the contact between the Kayenta and the Navajo in places seems to be gradational, but generally a thin jumbled mass of sandstone and shales, chunks of shale and limestone, mud balls, and concretions of lime and iron, lies at the base of the fine-grained, cross bedded Navajo. Mud cracks, a few ripple marks, and incipient drainage channels were observed in the topmost bed of the Kayenta on Red Rock Plateau; and in west Glen Canyon, wide sand-filled cracks appear at the horizon. These features indicate that, in places at least, the Wingate and Kayenta were exposed to erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is di ...
before their overlying geologic formations were deposited, are it may be that the range in thickness of the Kayenta thus in part (is) accounted for.
Southwest Utah
The red and mauve Kayenta siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...
s and sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates ...
s that form the slopes at base of the Navajo Sandstone
The Navajo Sandstone is a geological formation in the Glen Canyon Group that is spread across the U.S. states of southern Nevada, northern Arizona, northwest Colorado, and Utah as part of the Colorado Plateau province of the United States.Anonym ...
cliffs record the record of low to moderate energy streams. Poole (1997) has shown that the streams still flowed toward the east depositing from 150 to 210 m (500 to about 700 feet) of sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...
here. The sedimentary structures
Sedimentary structures include all kinds of features in sediments and sedimentary rocks, formed at the time of deposition.
Sediments and sedimentary rocks are characterized by bedding, which occurs when layers of sediment, with different partic ...
showing the channel and flood plain deposits of streams
A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams ...
are well exposed on switchbacks below the tunnel in Pine Creek Canyon.
In the southeastern part of Zion National Park a stratum of cross bedded sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates ...
is found roughly halfway between the top and bottom of the Kayenta Formation. It is a "tongue" of sandstone that merges with the Navajo formation east of Kanab, and it shows that desert conditions occurred briefly in this area during Kayenta time. This tongue is the ledge that shades the lower portion of the Emerald Pool Trail, and it is properly called Navajo, not Kayenta.
Fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
mudcracks attest to occasional seasonal climate
Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologica ...
, and thin limestones
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when t ...
and fossilized trails of aquatic snails
A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Ga ...
or worm
Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always).
Worms vary in size from microscopic to over in length for marine polychaete worm ...
s mark the existence of ponds and lake
A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much lar ...
s. The most interesting fossils, however, are the dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
tracks that are relatively common in Kayenta mudstone.
These vary in size, but all seem to be the tracks of three-toed reptiles
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephali ...
that walked upright, leaving their tracks in the muds on the flood plains. Unfortunately, so far no bone materials have been found in Washington County that would enable more specific identification.
Apparently during Kayenta time Zion was situated in a climatic belt like that of Senegal
Senegal,; Wolof: ''Senegaal''; Pulaar: 𞤅𞤫𞤲𞤫𞤺𞤢𞥄𞤤𞤠(Senegaali); Arabic: السنغال ''As-Sinighal'') officially the Republic of Senegal,; Wolof: ''Réewum Senegaal''; Pulaar : 𞤈𞤫𞤲𞤣𞤢𞥄𞤲𞤣𞤠...
with rainy summers and dry winters at the southern edge of a great desert. The influence of the desert was about to predominate, however, as North America drifted northward into the arid desert belt.
Glen Canyon
The Kayenta Formation is approximately thick and consists of a fine-grained sandstone interbedded with layers of siltstone. The alternation of these units generally produces a series of ledges and slopes between the cliffs of the Navajo and Moenave formation. Dinosaur tracks are fairly common in the siltstone, and fresh water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...
mussels
Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which ...
and snail
A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class G ...
s occur but are rare. The Kayenta Formation is colored pale red and adds to the splendor of the Vermilion Cliffs. It accumulated as deposits of rivers.
Fossils
Invertebrates
Fishes
The "Kayenta Fish Fauna" is the last one recovered from the Glen Canyon Group sequence and it is delimited mostly to the silty facies of the Lower-Middle Part of the formation. This Fauna is rather scarce and delimited to several concrete locations with proper lacustrine or fluvial deposition, and are also scarce due to preservation bias.[ Another aspect that can explain the lack of fish fossils found is the use of different research techniques than used on the ]Chinle Formation
The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. In ...
.[
]
Chondrichthyes
Actinopterygii
Sarcopterygii
Amphibia
Reptilia
Rhynchocephalia
Testudinatans
Crocodylomorphs
Dinosauria
Indeterminate ornithischian remains located in Arizona, USA. Ornithischian tracks located in Arizona, USA.[Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Jurassic, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): ''The Dinosauria'', 2nd, Berkeley: University of California Press. pp. 530–32. .] Indeterminate theropod remains located in Arizona, US. Theropod tracks located in Arizona and Utah, US. Possible theropod tracks located in Arizona, Colorado, and Utah, US.
Pterosauria
Synapsida
Ichnofossils
Plants
See also
* Kayenta, Arizona
* List of dinosaur-bearing rock formations
This list of dinosaur-bearing rock formations is a list of geologic formations in which dinosaur fossils have been documented.
Containing body fossils
* List of stratigraphic units with dinosaur body fossils
** List of stratigraphic units with f ...
* List of fossil sites
This list of fossil sites is a worldwide list of localities known well for the presence of fossils. Some entries in this list are notable for a single, unique find, while others are notable for the large number of fossils found there. Many of t ...
''(with link directory)''
Footnotes
References
* ''Geology of Eastern Iron County, Utah'' by Herbert E. Gregory
Herbert Ernest Gregory (October 15, 1869 – January 23, 1952) was a Yale University geologist well known for his early 20th-century explorations of the Colorado Plateau in Arizona and Utah. One of his most important works is ''Colorado Plateau Reg ...
Utah Geological and Mineral Survey Bulletin No. 37 (1950)
* ''The San Juan Country – A Geographic and Reconnaissance of Southeastern Utah'' by Herbert E. Gregory
Herbert Ernest Gregory (October 15, 1869 – January 23, 1952) was a Yale University geologist well known for his early 20th-century explorations of the Colorado Plateau in Arizona and Utah. One of his most important works is ''Colorado Plateau Reg ...
. U.S. Geological Survey Professional Paper No. 188
* ''Geology Studies,'' Vol. 15 Part 5 (1968)
* Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): ''The Dinosauria'', 2nd, Berkeley: University of California Press. 861 pp. .
External links
U.S.G.S Lexicon of Colorado Plateau Stratigraphy
{{Chronostratigraphy of Nevada
Sandstone formations of the United States
Siltstone formations
Geologic formations of Arizona
Geologic formations of Colorado
Geologic formations of Nevada
Geologic formations of Utah
Early Jurassic North America
Jurassic Arizona
Jurassic Colorado
Jurassic geology of Nevada
Jurassic geology of Utah
Paleontology in Arizona
Paleontology in Utah
Paleontology in Nevada
Jurassic System of North America
Ichnofossiliferous formations