![Hows-e Sultan](https://upload.wikimedia.org/wikipedia/commons/3/34/Hows-e_Sultan.jpg)
A dry lake bed, also known as a playa, is a basin or depression that formerly contained a standing surface water body, which disappears when evaporation processes exceeds recharge. If the floor of a dry lake is covered by deposits of alkaline compounds, it is known as an alkali flat. If covered with salt, it is known as a ''
salt flat.''
Terminology
If its basin is primarily
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
, then a dry lake bed is called a ''
salt pan'', ''pan'', or ''salt flat'' (the latter being a remnant of a
salt lake
A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per litre). ...
). ''Hardpan'' is the dry terminus of an internally drained basin in a dry climate, a designation typically used in the
Great Basin
The Great Basin is the largest area of contiguous endorheic basin, 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 ...
of the western United States.
![Tunisia 10-12 - 141 - Salt Flats (6609472321)](https://upload.wikimedia.org/wikipedia/commons/5/51/Tunisia_10-12_-_141_-_Salt_Flats_%286609472321%29.jpg)
Another term for dry lake bed is ''playa''. The Spanish word ''playa'' () literally means "beach". Dry lakes are known by this name in some parts of Mexico and the western United States. This term is used e.g. on the
Llano Estacado
The Llano Estacado (), sometimes translated into English as the Staked Plains, is a region in the Southwestern United States that encompasses parts of eastern New Mexico and northwestern Texas. One of the largest mesas or tablelands on the North A ...
and other parts of the Southern
High Plains High Plains refers to one of two distinct land regions:
* High Plains (United States), land region of the western Great Plains
*High Plains (Australia)
The High Plains of south-eastern Australia are a sub-region, or more strictly a string of adja ...
and is commonly used to address
paleolake
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 larger ...
sediments in the
Sahara
, photo = Sahara real color.jpg
, photo_caption = The Sahara taken by Apollo 17 astronauts, 1972
, map =
, map_image =
, location =
, country =
, country1 =
, ...
like
Lake Ptolemy
Lake Ptolemy is a former lake in Sudan. This lake formed during the Holocene in the Darfur region, during a time when the monsoon over Africa was stronger. The existence of the lake is dated between about 9,100–2,400 years before present. This ...
.
In South America, the usual term for a dry lake bed is ''salar'' or ''salina'', Spanish for ''salt pan''.
''Pan'' is the term used in most of South Africa. These may include the small round
highveld
The Highveld (Afrikaans: ''Hoëveld'', where ''veld'' means "field") is the portion of the South African inland plateau which has an altitude above roughly 1500 m, but below 2100 m, thus excluding the Lesotho mountain regions to the south-east of ...
pans, typical of the
Chrissiesmeer
Chrissiesmeer (Lake Chrissie) is a small town situated in Msukaligwa Local Municipality, in a wetland area of Mpumalanga province in South Africa, on the northern banks of the eponymous Lake Chrissie
Lake Chrissie ( af, Chrissiesmeer) is a la ...
area, to the extensive pans of the
Northern Cape
The Northern Cape is the largest and most sparsely populated province of South Africa. It was created in 1994 when the Cape Province was split up. Its capital is Kimberley. It includes the Kalahari Gemsbok National Park, part of the Kgalagadi T ...
province.
Terms used in Australia include ''salt pans'' (where
evaporite
An evaporite () is a water-soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as ocea ...
minerals are present) and ''clay pans''.
In Arabic, a salt flat is called a ''
sabkha
A sabkha ( ar, سبخة) is a coastal, supratidal mudflat or sandflat in which evaporite-saline minerals accumulate as the result of semiarid to arid climate. Sabkhas are gradational between land and intertidal zone within restricted coastal p ...
'' (also spelled ''sabkhah'', ''subkha'' or ''sebkha'') or ''shott'' (''
chott
In geology, a chott, shott, or shatt (; ar, شط, šaṭṭ, lit=bank, coast) is a salt lake in Africa's Maghreb that stays dry for much of the year but receives some water in the winter. The elevation of a chott surface is controlled by the pos ...
''). In Central Asia, a similar "cracked mud" salt flat is known as a
takyr. In
Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
salt flats are called ''kavir''.
Formation
![Racetrack Playa in Death Valley National Park](https://upload.wikimedia.org/wikipedia/commons/2/20/Racetrack_Playa_in_Death_Valley_National_Park.jpg)
A dry lake is formed when water from rain or other sources, like intersection with a water table, flows into a dry depression in the landscape, creating a pond or lake. If the total annual evaporation rate exceeds the total annual inflow, the depression will eventually become dry again, forming a dry lake. Salts originally dissolved in the water precipitate out and are left behind, gradually building up over time. A dry lake appears as a flat bed of clay, generally encrusted with precipitated salts. These evaporite minerals are a concentration of weathering products such as sodium carbonate, borax, and other salts. In deserts, a dry lake may be found in an area ringed by
bajadas.
Dry lakes are typically formed in semi-
arid
A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ar ...
to arid regions of the world. The largest concentration of dry lakes (nearly 22,000) is in the southern High Plains of
Texas
Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...
and eastern
New Mexico
)
, population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano)
, seat = Santa Fe
, LargestCity = Albuquerque
, LargestMetro = Tiguex
, OfficialLang = None
, Languages = English, Spanish ( New Mexican), Navajo, Ker ...
. Most dry lakes are small. However,
Salar de Uyuni
Salar de Uyuni (or "Salar de Tunupa") is the world's largest salt flat, or playa, at over in area. It is in the Daniel Campos Province in Potosí in southwest Bolivia, near the crest of the Andes at an elevation of above sea level.
The Sal ...
in
Bolivia
, image_flag = Bandera de Bolivia (Estado).svg
, flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center
, flag_alt2 = 7 × 7 square p ...
, near
Potosí
Potosí, known as Villa Imperial de Potosí in the colonial period, is the capital city and a municipality of the Department of Potosí in Bolivia. It is one of the highest cities in the world at a nominal . For centuries, it was the location o ...
, the largest salt flat in the world, comprises 4,085 square miles (10,582 square km).
Many dry lakes contain shallow water during the rainy season, especially during wet years. If the layer of water is thin and is moved around the dry lake bed by wind, an exceedingly hard and smooth surface may develop. Thicker layers of water may result in a "cracked-mud" surface and
teepee structure
Teepee (also spelled tepee or tipi) structures are sedimentary structures interpreted to represent formation in peritidal environments. Teepees are largely the result of evaporation of water and subsequent precipitation of minerals within sediment ...
desiccation features. If there is very little water,
dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...
s can form.
The
Racetrack Playa
The Racetrack Playa, or The Racetrack, is a scenic dry lake feature with " sailing stones" that inscribe linear "racetrack" imprints. It is located above the northwestern side of Death Valley, in Death Valley National Park, Inyo County, Califor ...
, located in
Death Valley, California
Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. During summer, it is the hottest place on Earth.
Death Valley's Badwater Basin is the point of lowest elevation in North A ...
, features a geological phenomenon known as "
sailing stones
Sailing stones (also called sliding rocks, walking rocks, rolling stones, and moving rocks) are part of the geological phenomenon in which rocks move and inscribe long tracks along a smooth valley floor without animal intervention. The movement ...
" that leave linear "racetrack" imprints as they slowly move across the surface without human or animal intervention. These rocks have been recently filmed in motion by the Scripps Institution of Oceanography at UC San Diego and are due to a perfect coincidence of events. First, the playa has to fill with water, which must be deep enough to form floating ice during winter, but still shallow enough that the rocks are exposed. When the temperature drops at night, this pond freezes into thin sheets of "windowpane" ice, which then must be thick enough to maintain strength, but thin enough to move freely. Finally, when the sun comes out, the ice melts and cracks into floating panels; these are blown across the playa by light winds, propelling the rocks in front of them. The stones only move once every two or three years and most tracks last for three or four years.
Ecology
While a dry lake bed is itself typically devoid of vegetation, they are commonly ringed by
shadscale
''Atriplex confertifolia'', the shadscale or spiny saltbush, is a species of evergreen shrub in the family Amaranthaceae, which is native to the western United States and northern Mexico
Mexico (Spanish: México), officially the United Me ...
,
saltbrush
''Atriplex'' () is a plant genus of about 250 species, known by the common names of saltbush and orache (; also spelled orach). It belongs to the subfamily Chenopodioideae of the family Amaranthaceae ''s.l.''.
The genus is quite variable and w ...
and other salt-tolerant plants that provide critical winter fodder for
livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals ...
and other
herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s.
![Seasonally flooded playa in SW Idaho](https://upload.wikimedia.org/wikipedia/commons/8/84/Seasonally_flooded_playa_in_SW_Idaho.JPG)
In southwest
Idaho
Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyom ...
and parts of
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 ...
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 it ...
there are a number of rare species that occur nowhere else but in the inhospitable environment of seasonally flooded playas. A new species of
giant fairy shrimp
''Branchinecta gigas'' is a species of fairy shrimp that lives in western Canada and the United States. It is the largest species of fairy shrimp, growing up to long. It is known commonly as the giant fairy shrimp.
Description
Females reach sex ...
was found in 2006. Although a large predatory species, it evaded detection because of the murkiness of the playa's water caused by winds and a fine clay load. This shrimp species is able to regenerate using tiny undetectable cysts that can remain in a dry lake bed for years until conditions are optimum for hatching.
''
Lepidium davisii
''Lepidium'' is a genus of plants in the mustard/cabbage family, Brassicaceae. The genus is widely distributed in the Americas, Africa, Asia, Europe, and Australia.[southern Idaho
Southern Idaho is a generic geographical term roughly analogous with the areas of the U.S. state of Idaho located in the Mountain Time Zone. It particularly refers to the combined areas of the Boise metropolitan area, the Magic Valley and Eastern ...]
and northern Nevada.
Far from major rivers or lakes, playas are often the only water available to wildlife in the desert.
Antelope
The term antelope is used to refer to many species of even-toed ruminant that are indigenous to various regions in Africa and Eurasia.
Antelope comprise a wastebasket taxon defined as any of numerous Old World grazing and browsing hoofed mammals ...
and other wildlife gather there after rainstorms to drink.
Threats to dry lakes include pollution from concentrated animal feeding operations such as cattle
feedlot
A feedlot or feed yard is a type of animal feeding operation (AFO) which is used in intensive animal farming, notably beef cattle, but also swine, horses, sheep, turkeys, chickens or ducks, prior to slaughter. Large beef feedlots are called conc ...
s and dairies. Results are erosion; fertilizer, pesticide and sediment runoff from farms; and
overgrazing
Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature res ...
.
A non-native shrub that has been used for rangeland restoration in the west, ''
Kochia prostrata
''Bassia prostrata'', the forage kochia, is a Eurasian plant in the subfamily Camphorosmoideae of the family Amaranthaceae
Amaranthaceae is a family of flowering plants commonly known as the amaranth family, in reference to its type genus ''A ...
'', also poses a significant threat to playas and their associated rare species, as it capable of crowding out native vegetation and draining a playa's standing water because of its root growth.
Human use
![01-2007-Trona-CA-01](https://upload.wikimedia.org/wikipedia/commons/4/4f/01-2007-Trona-CA-01.jpg)
The extremely flat, smooth and hard surfaces of dry lake beds make them ideal for fast motor vehicles and motorcycles. Large-sized dry lakes are excellent spots for pursuing
land speed record
The land speed record (or absolute land speed record) is the highest speed achieved by a person using a vehicle on land. There is no single body for validation and regulation; in practice the Category C ("Special Vehicles") flying start regula ...
s, as the smoothness of the surface allows low-clearance vehicles to travel very fast without any risk of disruption by surface irregularities, and the path traveled has no obstacles to avoid. The dry lake beds at
Bonneville Salt Flats
The Bonneville Salt Flats are a densely packed salt pan in Tooele County in northwestern Utah. A remnant of the Pleistocene Lake Bonneville, it is the largest of many salt flats west of the Great Salt Lake. It is public land managed by the Bur ...
in Utah and
Black Rock Desert
__NOTOC__
The Black Rock Desert is a semi-arid region (in the Great Basin shrub steppe eco-region) of lava beds and playa, or alkali flats, situated in the Black Rock Desert–High Rock Canyon Emigrant Trails National Conservation Area, a si ...
in
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 ...
have both been used for setting land speed records.
Lake Eyre
Lake Eyre ( ), officially known as Kati Thanda–Lake Eyre, is an endorheic lake in east-central Far North South Australia, some north of Adelaide. The shallow lake is the depocentre of the vast endorheic Lake Eyre basin, and contains the ...
and
Lake Gairdner
Lake Gairdner is a large endorheic salt lake in the Australian state of South Australia, to the north of the Eyre Peninsula. When in flood, the lake is considered the third largest salt lake in Australia.
Description
Lake Gairdner is located a ...
in
South Australia
South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...
have also been used for various land speed record attempts. Dry lake beds that very rarely fill with water are sometimes used as locations for air bases, for similar reasons. Examples include
Groom Lake
Area 51 is the common name of a highly classified United States Air Force (USAF) facility within the Nevada Test and Training Range. A remote detachment administered by Edwards Air Force Base, the facility is officially called Homey Airport ...
at
Area 51
Area 51 is the common name of a highly classified United States Air Force (USAF) facility within the Nevada Test and Training Range. A remote detachment administered by Edwards Air Force Base, the facility is officially called Homey Airport ...
in Nevada, and
Edwards Air Force Base
Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, but its eastern end is in San Bernardino County and a southern arm is in Los Angeles County. The hub of the base is E ...
(originally known as Muroc Dry Lake) in California.
Brine
Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for br ...
s from the subsurface of dry lakes are often
exploited for valuable minerals in solution. See, for example
Searles Dry Lake
Searles Lake is an endorheic dry lake in the Searles Valley of the Mojave Desert, in northwestern San Bernardino County, California. The lake in the past was also called Slate Range Lake and Borax Lake.
The mining community of Trona is on its w ...
and
Lithium resources.
Under United States law, a "playa lake" may be considered isolated
wetland
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...
s, and may be eligible to enroll in the new wetlands component of the
Conservation Reserve Program
The Conservation Reserve Program (CRP) is a cost-share and rental payment program of the United States Department of Agriculture (USDA). Under the program, the government pays farmers to take certain agriculturally used croplands out of produc ...
, enacted in the
2002 farm bill
The Farm Security and Rural Investment Act of 2002, also known as the 2002 Farm Bill, includes ten titles, addressing a great variety of issues related to agriculture, ecology, energy, trade, and nutrition. This act has been superseded by the 2007 ...
(P.L. 107–171, Sec. 2101).
The
Burning Man
Burning Man is an event focused on community, art, self-expression, and self-reliance held annually in the western United States. The name of the event comes from its culminating ceremony: the symbolic burning of a large wooden effigy, referred ...
yearly event takes place in a playa in the
Black Rock Desert
__NOTOC__
The Black Rock Desert is a semi-arid region (in the Great Basin shrub steppe eco-region) of lava beds and playa, or alkali flats, situated in the Black Rock Desert–High Rock Canyon Emigrant Trails National Conservation Area, a si ...
in western Nevada every year.
Gallery
File:Devil's Golf Course in Death Valley NP.jpg, Devil's Golf Course in Death Valley National Park
Death Valley National Park is an American national park that straddles the California–Nevada border, east of the Sierra Nevada. The park boundaries include Death Valley, the northern section of Panamint Valley, the southern section of Eureka ...
, western United States
Image:Lake Hart.jpg,
Image:Jfader playa.jpg,
Image:EtoshaPan 2005-06 comparison.jpg,
See also
*
*
*
*
References
Bibliography
*
*John H. Wellington, ''Southern Africa: a geographical study'', Chapter 16 LAKES AND PANS
{{Authority control
Endorheic lakes
Aeolian landforms
Lacustrine landforms