The Painted Hills is a geologic site in

Wheeler County, Oregon Wheeler County is a county in the U.S. state of Oregon. As of the 2020 census, the population was 1,451, making it Oregon's least populous county. It is named in honor of Henry H. Wheeler. an early settler who owned a farm near Mitchell. ...

that is one of the three units of the

John Day Fossil Beds National Monument John Day Fossil Beds National Monument is a U.S. national monument in Wheeler and Grant counties in east-central Oregon. Located within the John Day River basin and managed by the National Park Service, the park is known for its well-preserve ...

along with Sheep Rock and Clarno. It totals and is located northwest of

Mitchell, Oregon Mitchell is a city in Wheeler County, Oregon, Wheeler County, Oregon, United States. The population was 130 at the 2010 United States Census, 2010 census. It was founded in 1873 and was named after John H. Mitchell, a politician. The Painted Hil ...

. The Painted Hills are listed as one of the Seven Wonders of Oregon. The layers of color for which the site is named can be traced back to cycling periods of wet and dry climate conditions associated with the transition from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

epoch to the cooler, more temperate

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

epoch. The different layers of colors are due to the soil being composed of a combination of

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...

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. Although its permeabil ...

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

and

lignite Lignite (derived from Latin ''lignum'' meaning 'wood'), often referred to as brown coal, is a soft, brown, combustible sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35% and is considered the lowest ...

Geology

Formation

The Painted Hills began to form 35 million years ago when pumice and ash from volcanic eruptions in the

Cascade Mountains The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as many of those in the ...

traveled 100 miles east and settled over the area. Once there, the ash and other sediments were mixed by natural processes including the flow of water, growth of plants, and the movement of animals. Over time, this led to oxidation of the ash on the surface. Buried under new layers and deposits, the ash turned into soils by way of compaction and cementation. With more time and weathering, the exterior surfaces of The Painted Hills were worn into clay. Now, they are primarily made of hard

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone and shale. Most of the particles of which the stone is composed are less than and are too small to ...

layers.Painted Hills Viewpoint
from the John Day Fossil Beds National Monument National Park Service.

Layers

The colors of the Painted Hills come from the combination of elements including

Aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

Silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...

Iron Iron is a chemical element; it has symbol Fe () 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, forming much of Earth's o ...

Magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

Manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

Sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

Calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

Phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

Titanium Titanium is a chemical element; it has symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...

Potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

Oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

, and

Hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

, among others, which arrived with the initial ash fall. Originally light in color, the ash mixed with soils and other elements to form the minerals that give the hills colors such as red, yellow, and black. The alternating red and tan layers within the hills are the result of cycling climate conditions, which were alternately warm and wet or cool and dry for a period of time between 34 and 28 million years ago. As the mild, humid

epoch gave way to the

, the tropical climate shifted, becoming cooler and drier.Bestland, E.A., Hammond, P.E., Blackwell, D.L.S., Kays, M.A., Retallack, G.J., & Stimac, J. (2002).
Geologic Framework of the Clarno Unit, John Day Fossil Beds National Monument, Central Oregon
(PDF). Red soils came from floodplain deposits during the more tropical periods, and are made up of

laterite Laterite is a soil type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by intensive and prolo ...

s, or soils rich in

iron Iron is a chemical element; it has symbol Fe () 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, forming much of Earth's o ...

and

aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

. These rust-colored layers are full of

and

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

in the form of

iron oxide An iron oxide is a chemical compound composed of iron and oxygen. Several iron oxides are recognized. Often they are non-stoichiometric. Ferric oxyhydroxides are a related class of compounds, perhaps the best known of which is rust. Iron ...

. The yellow layers are from a drier and cooler time and take on their yellow hue from

and

magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...

s. The darker, black soil is

that was once vegetative matter that grew along the floodplain. The grey coloring is

, and

. The black marks on the hills get their color from

manganese oxide Manganese oxide is any of a variety of manganese oxides and hydroxides.Wells A.F. (1984) ''Structural inorganic chemistry'' 5th edition Oxford Science Publications, . These include * Manganese(II) oxide, MnO * Manganese(II,III) oxide, Mn3O4 * Man ...

Fossils

Fossils are rare in the Painted Hills. The original deposits of ash arrived irregularly, creating poor conditions for

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 preserve ...

ization, and most organic matter decayed. Still, it is possible to find leaf fossils from ancient lake beds throughout the hills. Many of the fossilized leaf impressions that have been found indicate the presence of plants and trees including

redwood Sequoioideae, commonly referred to as redwoods, is a subfamily of Pinophyta, coniferous trees within the family (biology), family Cupressaceae, that range in the Northern Hemisphere, northern hemisphere. It includes the List of superlative tree ...

cinnamon Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, biscuits, b ...

fig The fig is the edible fruit of ''Ficus carica'', a species of tree or shrub in the flowering plant family Moraceae, native to the Mediterranean region, together with western and southern Asia. It has been cultivated since ancient times and i ...

, and

alder Alders are trees of the genus ''Alnus'' in the birch family Betulaceae. The genus includes about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few species ex ...

, which correspond to the warmer, more humid climate that predominated during the early formation of the hills. An abundance of fossil remains of early horses, camels, and rhinoceroses in the larger Painted Hills unit makes the area particularly important to vertebrate paleontologists.

Recreation

The Painted Hills are listed as one of the Seven Wonders of Oregon. The Painted Hills unit is open year-round with access for all visitors, but recreation can take a toll on the landscape; visitors who step off the trails can disrupt the naturally-occurring mineral layers, and damage the hills' visible features. There are several well-marked trails for visitors, who are encouraged to take a pledge to stay on the trails at all times: 'Don't Hurt the Dirt', and 'Leave No Trace'. On any given day, depending on the weather and the moisture in the hills, visitors might find variations in the colors of the Painted Hills. Light reflects differently when they are wet, causing the shades of color to vary in brightness and hue. In 2015, the annual visitor count at the Painted Hills rose from 45,849 to 74,873. On August 21, 2017, the Great American Eclipse passed directly over the park, allowing visitors a duration of totality of just over 2 minutes, 4 seconds.

Gallery

File: Painted Hills 2009.08.13.11.08.19.jpg File: Painted Hills 2009.08.13.11.08.52.jpg File: Painted Hills 2009.08.13.11.08.56.jpg File: Painted Hills in the John Day Fossil Beds National Monument near Mitchell Oregon.ogv, Bands of

give Painted Hills in the John Day Fossil Beds National Monument near Mitchell, Oregon their colorful appearance.

References

External links

* * Travel Oregon
/ref> – Painted Hills {{National Register of Historic Places Oregon John Day Fossil Beds National Monument Protected areas of Wheeler County, Oregon Articles containing video clips Landforms of Wheeler County, Oregon