Badlands are a type of dry terrain where softersedimentary rocks andclay-richsoils have been extensivelyeroded.[1] They are characterized by steep slopes, minimalvegetation, lack of a substantialregolith, and highdrainage density.[2]Ravines,gullies,buttes,hoodoos and other suchgeologic forms are common in badlands.
Badlands are found on every continent except Antarctica, being most common where there areunconsolidatedsediments. They are often difficult to navigate by foot, and are unsuitable for agriculture. Most are a result of natural processes, but destruction of vegetation byovergrazing orpollution can produceanthropogenic badlands.
Badlands are characterized by a distinctivebadlands topography.[3][4] This is terrain in which watererosion has cut a very large number of deep drainage channels, separated by short, steep ridges (interfluves).[5] Such a drainage system is said to have a very fine drainage texture,[6] as measured by itsdrainage density. Drainage density is defined as the total length of drainage channels per unit area of land surface. Badlands have a very high drainage density of 48 to 464 kilometres per square kilometre (77 to 747 miles per square mile).[5] The numerous deep drainage channels and highinterfluves creates a stark landscape ofhills,gullies, andravines.[3]
In addition to a dense system of drainages and interfluves, badlands often containbuttes andhoodoos. These are formed by resistant beds of sandstone, which form thecaprock of the buttes and hoodoos.[4]
Badlands arise from a combination of an impermeable but easily eroded ground surface, sparsevegetation, and infrequent but heavy rainfall.[6] The surfacebedrock is typicallymudrock, sometimes withevaporites, with only occasional beds of more resistantsandstone.[5] Infrequent heavy rains lead to heavy erosional dissection. Where sudden precipitation cannot penetrate impermeable clays, it is channeled into a very dense system of streamlets that erode a dense system of ever-enlarging, coalescing gulleys and ravines. Erosion is enhanced by pelting raindrops that dislodge soft sediments. The presence ofbentonite clay further increaseserodibility, as canrejuvenation of the drainage system from regionaluplift, as occurred atBadlands National Park.[4]
In addition to surface erosion, badlands sometimes have well-developedpiping, which is a system of pipes, joints,caverns, and other connected void spaces in the subsurface through which water can drain. However, this is not a universal feature of badlands. For example, theHenry Mountains badlands show very little piping.[2]
The precise processes by which the erosion responses take place vary depending on the precise interbedding of the sedimentary material.[7] However, it has been estimated that the badlands of Badlands National Park erode at the relatively high rate of about one inch or 25 millimetres per year.[8] TheWhite River draining Badlands National Park was so named for its heavy load of bentonite clay eroded from the badlands.[4]
Badlands are partially characterized by their thin to nonexistentregolith layers. The regolith profiles of badlands in arid climates are likely to resemble one another. In these regions, the upper layer (~1–5 cm or 0.4–2.0 in) is typically composed ofsilt,shale, andsand (a byproduct of theweathered shale). This layer can form either a compact crust or a looser, more irregular aggregation of "popcorn" fragments. Located beneath the top layer is a sublayer (~5–10 cm or 2.0–3.9 in), below which can be found a transitional shard layer (~10–40 cm or 3.9–15.7 in), formed largely of loose disaggregated shale chips, which in turn eventually gives way to a layer of unweathered shale. Badlands such as those found in theMancos Shale, theBrule Formation, theChadron Formation, and theDinosaur Provincial Park can be generally said to fit this profile.[2]
In less arid regions, the regolith profile can vary considerably. Some badlands have no regolith layer whatsoever, capping instead in bare rock such assandstone. Others have a regolith with a clay veneer, and still others have a biological crust ofalgae orlichens.[2]
In addition to lacking significant regolith, they also lack much vegetation. The lack of vegetation could very well be a result of the lack of a substantial regolith.[9]
Although most badland topography is natural, badlands have been produced artificially by destruction of vegetation cover, throughovergrazing,acid rain, oracid mine drainage.[5] TheCheltenham Badlands inCaledon, Ontario are an example of badlands produced bypoor farming practices. In the early 1900s, the area was used for agricultural purposes, predominantly cattlegrazing. Agricultural use ceased by 1931 and natural recovery of the majority of the property began.[10] Once established, however, this type of erosion can continue rapidly, if land clearing, overgrazing, and increased foot traffic by humans persists, as the shale is highly susceptible to erosion.[11]
An example of badlands created bymining is theRoman gold mine ofLas Médulas in northern Spain.[citation needed]
The wordbadlands is acalque from theCanadian French phraseles mauvaises terres, as the early French fur traders called theWhite River badlandsles mauvaises terres à traverser or 'bad lands to traverse', perhaps influenced by theLakota people who moved there in the late 1700s and who referred to the terrain asmako sica, meaning 'bad land' or 'eroded land'.[12]
The termmalpaís means 'badlands' inSpanish,[13] but refers to a terrain oflava flows that is unlike the eroded badlands of the White River.[14]
Badlands are generally unsuitable for agriculture, but attempts have been made to remediate badlands. For example,reforestation is being attempted in theGarbeta badlands of Eastern India.[15]Revegetation and reforestation have been studied in the blackmarl badlands of the FrenchAlps.Austrian black pine can become established and then be gradually replaced by nativedeciduous species. However, the time scale for this process is many decades.[16]
Badlands are found on all thecontinents exceptAntarctica. The presence of unconsolidated sediments is a strong control on their locations.[17]
TheValle de la Luna ("Valley of the Moon") is one of many examples of badland formations in midwesternArgentina.[18]
TheCheltenham Badlands are inCaledon, Ontario, not far from Canada's largest cityToronto.[19]
TheBig Muddy Badlands inSaskatchewan[20] gained notoriety as a hideout foroutlaws.[21]
There is a large badland area inAlberta, particularly in the valley of theRed Deer River, whereDinosaur Provincial Park is located, as well as inDrumheller, where theRoyal Tyrrell Museum of Palaeontology is located.[22]
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Zhangye National Geopark is a badlands area known for its colorful rock formations. It was voted by Chinese media outlets as one of the most beautiful landforms in China and became aUNESCO Global Geopark in 2019.[23]
Garbeta, Eastern India is a badlands located in a monsoon climate.[15]Chambal[24] spread across northern parts ofMadhya Pradesh, southeasternRajasthan and southern parts ofUttar Pradesh known for its lawlessness anddacoity is another example of badlands. A small strip of badlands is also found in westernUttar Pradesh andHaryana.
InItaly, badlands are called "calanchi". Some examples areAliano (Basilicata),Crete Senesi (Tuscany) andCivita di Bagnoregio (Lazio).
A well-known badlands formation inNew Zealand – thePūtangirua Pinnacles, formed by the erosion of theconglomerate of an oldalluvial fan – is located at the head of a small valley near the southern tip of theNorth Island.[25][26]
TheBardenas Reales nearTudela, Navarre, theTabernas Desert inTabernas, Almería, parts of the Granada Altiplano nearGuadix and possiblyLos Monegros inAragon are examples ofSpanish badlands.
Turkey has extensive badlands,[17] includingGöreme National Park.[27]
In the U.S.,Makoshika State Park inMontana andBadlands National Park inSouth Dakota are examples of extensive badland formations. Also located in this region isTheodore Roosevelt National Park, a United States National Park composed of three geographically separated areas of badlands in westernNorth Dakota named after former U.S. PresidentTheodore Roosevelt.Petrified Forest National Park inArizona which is part ofNavajo County encompasses numerous badlands that also abuts theNavajo Indian Reservation and is directly north ofJoseph City, Arizona. Manydinosaurs are believed to be buried in the immediate area and exploration has been ongoing since the early 20th century.[28]
Among theHenry Mountains area in Utah, about 4,900 ft (1,500 m) above sea level,Cretaceous- andJurassic-aged shales are exposed.[2] Another popular area of badland formations isToadstool Geologic Park in theOglala National Grassland located in northwesternNebraska.Dinosaur National Monument in Colorado and Utah are also badlands settings, along with several other areas in southern Utah, such as the Chinle Badlands inGrand Staircase–Escalante National Monument. A small badland calledHell's Half-Acre is present inNatrona County,Wyoming. Additional badlands also exist in various places throughout southwest Wyoming, such as nearPinedale and in theBridger Valley near the towns ofLyman andMountain View, near the highUintah Mountains.Pinnacles National Park in California also has areas of badlands, as does theMojave Desert ineastern California.
Badlands have become a populartrope inside various media, particularlywesterns.[29]
