The Navajo Sandstone is a geological

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

in the

Glen Canyon Group The Glen Canyon Group is a geologic group of formations that is spread across the U.S. states of Nevada, Utah, northern Arizona, north west New Mexico and western Colorado. It is called the Glen Canyon Sandstone in the Green River Basin of C ...

that is spread across the U.S. states of southern

Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, 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. N ...

, northern

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

, northwest

Colorado Colorado (, other variants) is a state in the 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 western edge of the ...

, 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 ...

as part of 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 o ...

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 Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

.Anonymous (2011b
''Navajo Sandstone''

. U.S. Geological Survey, Reston, Virginia. last accessed August 18, 2013

Description

The Navajo Sandstone is particularly prominent in southern Utah, where it forms the main attractions of a number of national parks and monuments including

Red Rock Canyon National Conservation Area The Red Rock Canyon National Conservation Area in Clark County, Nevada, is an area managed by the Bureau of Land Management as part of its National Landscape Conservation System, and protected as a National Conservation Area. It is about west ...

,''Red Rock Canyon National Conservation Area - Rock Climbing.''
Southern Nevada District Office, Bureau of Land Management, Reno, Nevada

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 of ...

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 ...

Glen Canyon National Recreation Area Glen Canyon National Recreation Area (shortened to Glen Canyon NRA or GCNRA) is a national recreation area and conservation unit of the United States National Park Service that encompasses the area around Lake Powell and lower Cataract Canyo ...

Grand Staircase–Escalante National Monument The Grand Staircase–Escalante National Monument (GSENM) is a United States national monument protecting the Grand Staircase, the Kaiparowits Plateau, and the Canyons of the Escalante ( Escalante River) in southern Utah. It was established in ...

, 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 ...

. Navajo Sandstone frequently overlies and interfingers with the

Kayenta Formation The Kayenta Formation is a geological formation in the Glen Canyon Group that is spread across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. Traditionally has been suggested ...

of the Glen Canyon Group. Together, these formations can result in immense vertical cliffs of up to . Atop the cliffs, Navajo Sandstone often appears as massive rounded domes and bluffs that are generally white in color.

Appearance and provenance

Navajo Sandstone frequently occurs as spectacular cliffs,

cuesta A cuesta (from Spanish ''cuesta'' "slope") is a hill or ridge with a gentle slope on one side, and a steep slope on the other. In geology the term is more specifically applied to a ridge where a harder sedimentary rock overlies a softer laye ...

s, domes, and bluffs rising from the desert floor. It can be distinguished from adjacent Jurassic sandstones by its white to light pink color, meter-scale

cross-bedding In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers. The origina ...

, and distinctive rounded weathering. The wide range of colors exhibited by the Navajo Sandstone reflect a long history of alteration by groundwater and other subsurface fluids over the last 190 million years. The different colors, except for white, are caused by the presence of varying mixtures and amounts of

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...

goethite Goethite (, ) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the "α" polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient t ...

, and

limonite Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·H2O, although this is not entirely accurate as the ratio of oxide to hydroxide ...

filling the pore space within the quartz sand comprising the Navajo Sandstone. The iron in these strata originally arrived via the erosion of iron-bearing

silicate In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is a ...

minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed ...

. Initially, this iron accumulated as iron-oxide coatings, which formed slowly after the sand had been deposited. Later, after having been deeply buried, reducing fluids composed of water and hydrocarbons flowed through the thick red sand which once comprised the Navajo Sandstone. The dissolution of the iron coatings by the reducing fluids bleached large volumes of the Navajo Sandstone a brilliant white. Reducing fluids transported the iron in solution until they mixed with oxidizing groundwater. Where the oxidizing and reducing fluids mixed, the iron precipitated within the Navajo Sandstone. Depending on local variations within the permeability, porosity, fracturing, and other inherent rock properties of the sandstone, varying mixtures of hematite, goethite, and limonite precipitated within spaces between quartz grains. Variations in the type and proportions of precipitated iron oxides resulted in the different black, brown, crimson, vermillion, orange, salmon, peach, pink, gold, and yellow colors of the Navajo Sandstone. The precipitation of iron oxides also formed laminae, corrugated layers, columns, and pipes of ironstone within the Navajo Sandstone. Being harder and more resistant to erosion than the surrounding sandstone, the ironstone weathered out as ledges, walls, fins, "flags", towers, and other minor features, which stick out and above the local landscape in unusual shapes.Chan, MA, and WT Parry (2002
''Mysteries of Sandstone Colors and Concretions in Colorado Plateau Canyon Country.'' PDF version, 468 KB
Public Information Series no. 77. Utah Geological Survey, Salt Lake City, Utah.Chan, M., BB Beitler, WT Parry, J Ormo, and G Komatsu (2005
''Red Rock and Red Planet Diagenesis: Comparison of Earth and Mars Concretions.'' PDF version, 3.4 MB
GSA Today. vol. 15, no. 8, pp. 4–10.

Age and history of investigation

The age of the Navajo Sandstone is somewhat controversial. It may originate from the

Late Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch ...

but is at least as young as the

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...

stages

Pliensbachian The Pliensbachian is an age (geology), age of the geologic timescale and stage (stratigraphy), stage in the stratigraphic column. It is part of the Early Jurassic, Early or Lower Jurassic epoch (geology), Epoch or series (stratigraphy), Series an ...

and

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 Toar ...

. There is no type locality of the name. It was simply named for the 'Navajo Country' of the

southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, N ...

. The two major subunits of the Navajo are the Lamb Point Tongue (Kanab area) and the Shurtz Sandstone Tongue (Cedar City area).Averitt, P and RF Wilson, JS Detterman, JW Harshbarger, CA Repenning (1955) ''Revisions in correlation and nomenclature of Triassic and Jurassic formations in southwestern Utah and northern Arizona.'' American Association of Petroleum Geologists Bulletin. 39(12):2515–2524. The Navajo Sandstone was originally named as the uppermost formation of the La Plata Group by Gregory and Stone in 1917. Baker reassigned it as the upper formation of Glen Canyon Group in 1936.Baker, AA (1936) ''Geology of the Monument Valley-Navajo Mountain region, San Juan County, Utah.'' Bulletin no. 865. U.S. Geological Survey, Reston, Virginia. 106 pp. Its age was modified by Lewis and others in 1961.Lewis, GE, JH Irwin, and RF Wilson (1961) ''Age of the Glen Canyon Group (Triassic and Jurassic) on the Colorado Plateau. '' Geological Society of America Bulletin. 72(9):1437–1440. The name was originally not used in northwest Colorado and northeast Utah, where the name 'Glen Canyon Sandstone' was preferred.Poole, FG, and JH Stewart (1964) ''Chinle Formation and Glen Canyon Sandstone in northeastern Utah and northwestern Colorado.'' In Geological Survey research 1964. Professional Paper, no. 501-D, pp. D30-D39, U.S. Geological Survey, Reston, Virginia. Its age was modified again by Padian in 1989.Padian, K (1989) ''Presence of dinosaur Scelidosaurus indicates Jurassic age for the Kayenta Formation (Glen Canyon Group, northern Arizona).'' Geology. 17(5):438-441. A 2019 radioisotopic analysis suggests that the Navajo Sandstone formation is entirely Jurassic, extending for about 5.5 million years from the Hettangian age to the Sinemurian age.Judith Totman Parrish, E. Troy Rasbury, Marjorie A. Chan & Stephen T. Hasiotis (2019) ''Earliest Jurassic U-Pb ages from carbonate deposits in the Navajo Sandstone, southeastern Utah, USA.'' Geology 47(11): 1015-1019.

Depositional environment

The

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 silicat ...

was deposited in an arid

erg The erg is a unit of energy equal to 10−7joules (100 nJ). It originated in the Centimetre–gram–second system of units (CGS). It has the symbol ''erg''. The erg is not an SI unit. Its name is derived from (), a Greek word meaning 'work' o ...

on the Western portion of the Supercontinent

Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...

. This region was affected by annual monsoons that came about each winter when cooler winds and wind reversal occurred.

Outcrop localities

Navajo Sandstone outcrops are found in these geologic locations: *

* Black Mesa Basin *

Great Basin The Great Basin is the largest area of contiguous endorheic watersheds, those with no outlets, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California. It is noted fo ...

province * Paradox Basin * Piceance Basin *

Plateau Sedimentary Province 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 of ...

* San Juan Basin *

Uinta Basin The Uinta Basin (also known as the Uintah Basin) is a physiographic section of the larger Colorado Plateaus province, which in turn is part of the larger Intermontane Plateaus physiographic division. It is also a geologic structural basin in ...

Uinta Uplift The Uinta Mountains ( ) are an east-west trending chain of mountains in northeastern Utah extending slightly into southern Wyoming in the United States. As a subrange of the Rocky Mountains, they are unusual for being the highest range in the co ...

* Uncompaghre Uplift The formation is also found in these parklands (incomplete list): *

Arches National Park Arches National Park is a national park in eastern Utah, United States. The park is adjacent to the Colorado River, north of Moab, Utah. More than 2,000 natural sandstone arches are located in the park, including the well-known Delicate Arch, ...

Dinosaur National Monument Dinosaur National Monument is an American national monument located on the southeast flank of the Uinta Mountains on the border between Colorado and Utah at the confluence of the Green and Yampa rivers. Although most of the monument area is i ...

Navajo National Monument Navajo National Monument is a National Monument located within the northwest portion of the Navajo Nation territory in northern Arizona, which was established to preserve three well-preserved cliff dwellings of the Ancestral Puebloan people: Keet ...

Colorado National Monument Colorado National Monument is a National Park Service unit near the city of Grand Junction, Colorado. Sheer-walled canyons cut deep into sandstone and granite–gneiss–schist rock formations. This is an area of desert land high on the Colorad ...

* Pink coral sand dunes, Kanab, Utah

Vertebrate paleofauna

Ornithodires

Indeterminate theropod remains geographically located in Arizona, USA.Weishampel, DB, P Dodson, and H Osmólska, Halszka (2007) ''The Dinosauria,'' 2nd, Berkeley: University of California Press. 861 pp. . Theropod tracks are geographically located in Arizona, Colorado, and Utah, USA. Ornithischian tracks located in Arizona, USA.

Iron oxide concretions

The Navajo Sandstone is also well known among

rockhound Amateur geology or rock collecting (also referred to as rockhounding in the United States and Canada) is the non-professional study and hobby of collecting rocks and minerals or fossil specimens from the natural environment.Sinkankas, John. Minera ...

s for its hundreds of thousands of

iron oxide Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of wh ...

concretion 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 ...

s. Informally, they are called "Moqui marbles" and are believed to represent an extension of

Hopi The Hopi are a Native American ethnic group who primarily live on the Hopi Reservation in northeastern Arizona, United States. As of the 2010 census, there are 19,338 Hopi in the country. The Hopi Tribe is a sovereign nation within the United ...

Native American traditions regarding ancestor worship ("moqui" translates to "the dead" in the Hopi language). Thousands of these concretions weather out of outcrops of the Navajo Sandstone within south-central and southeastern Utah within an area extending from Zion National Park eastward to Arches and Canyonland national parks. They are quite abundant within Grand Staircase–Escalante National Monument. The iron oxide concretions found in the Navajo Sandstone exhibit a wide variety of sizes and shapes. Their shape ranges from spheres to discs; buttons; spiked balls; cylindrical hollow pipe-like forms; and other odd shapes. Although many of these concretions are fused together like soap bubbles, many more also occur as isolated concretions, which range in diameter from the size of peas to baseballs. The surface of these spherical concretions can range from being very rough to quite smooth. Some of the concretions are grooved spheres with ridges around their circumference. The abundant concretions found in the Navajo Sandstone consist of sandstone cemented together by

(Fe₂O₃), and

(FeOOH). The iron forming these concretions came from the breakdown of iron-bearing

silicate minerals Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually con ...

by weathering to form iron oxide coatings on other grains. During later

diagenesis Diagenesis () is the process that describes physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play a ...

of the Navajo Sandstone while deeply buried, reducing fluids, likely

hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...

, dissolved these coatings. When the reducing fluids containing dissolved iron mixed with oxidizing

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit ...

, they and the dissolved iron were oxidized. This caused the iron to precipitate out as hematite and goethite to form the innumerable concretions found in the Navajo Sandstone. Evidence suggests that microbial metabolism may have contributed to the formation of some of these concretions.Weber, WA, TL Spanbauer, D Wacey, MR Kilburn, DB Loope, and RM Kettler (2012) ''Biosignatures link microorganisms to iron mineralization in a paleoaquifer.'' Geology. 40(8):747–750. These concretions are regarded as terrestrial analogues of the hematite spherules, called alternately Martian "blueberries" or more technically

Martian spherules Martian spherules (also known as hematite spherules, blueberries, & Martian blueberries) are small spherules (roughly spherical pebbles) that are rich in an iron oxide (grey hematite, α-Fe2O3) and are found at Meridiani Planum (a large plain on ...

, which the

Opportunity rover ''Opportunity'', also known as MER-B (Mars Exploration Rover – B) or MER-1, is a robotic rover that was active on Mars from 2004 until 2018. ''Opportunity'' was operational on Mars for sols (). Launched on July 7, 2003, as part of NASA's ...

found at

Meridiani Planum The Meridiani Planum (alternately Meridiani plain, Meridiani plains, Terra Meridiani, or Terra Meridiani plains) is either a large plain straddling the equator of Mars and covered with a vast number of spherules containing a lot of iron oxide or ...

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

Description

Appearance and provenance

Age and history of investigation

Depositional environment

Outcrop localities

Vertebrate paleofauna

Ornithodires

Iron oxide concretions

See also

References

Further reading

General

Scientific publications