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66-463: 41°27′03″S 175°13′20″E  /  41.4507°S 175.2223°E  / -41.4507; 175.2223 The Pūtangirua Pinnacles (also known colloquially simply as The Pinnacles ) are a geological formation and one of New Zealand's best examples of badlands erosion . They consist of a large number of earth pillars or hoodoos located at the head of a valley in the Aorangi Ranges , on

132-652: A UNESCO Global Geopark in 2019. Garbeta , Eastern India is a badlands located in a monsoon climate. Chambal spread across northern parts of Madhya Pradesh , southeastern Rajasthan and southern parts of Uttar Pradesh known for its lawlessness and dacoity is another example of badlands. A small strip of badlands is also found in western Uttar Pradesh and Haryana . In Italy , badlands are called "calanchi". Some examples are Aliano ( Basilicata ), Crete Senesi ( Tuscany ) and Civita di Bagnoregio ( Lazio ). A well-known badlands formation in New Zealand –

198-790: A desiccant due to its adsorption properties. Bentonite desiccants have been successfully used to protect pharmaceutical, nutraceutical, and diagnostic products from moisture degradation and extend shelf life . In most common package environments, bentonite desiccants offer a higher water adsorption capacity than silica gel desiccants. Bentonite complies with the FDA for contact with food and drugs. The application of clay technology by farmers in northeast Thailand, using bentonite clay, has dramatically reversed soil degradation and resulted in greater economic returns, with higher yields and higher output prices. Studies carried out by The International Water Management Institute and partners in 2002–2003 focused on

264-403: A foundry-sand bond in iron and steel foundries . Sodium bentonite is most commonly used for large castings that use dry molds, while calcium bentonite is more commonly used for smaller castings that use "green" or wet molds. Bentonite is also used as a binding agent in the manufacture of iron ore ( taconite ) pellets as used in the steelmaking industry . Bentonite, in small percentages,

330-444: A viscous , shear-thinning material. Most often, bentonite suspensions are also thixotropic , although rare cases of rheopectic behavior have also been reported. At high enough concentrations (about 60 grams of bentonite per litre of suspension , ~6wt.%), bentonite suspensions begin to take on the characteristics of a gel (a fluid with a minimum yield strength required to make it move). Bentonite has been widely used as

396-411: A base for many dermatologic formulas. Granular bentonite is being studied for use in battlefield wound dressings. Bentonite is also sold online and in retail outlets for a variety of indications. Bentoquatam is a bentonate-based topical medication intended to act as a shield against exposure to urushiol , the oil found in plants such as poison ivy or poison oak . Bentonite can also be used as

462-477: A chemical absorbent and container sealant. In 2018, China was the top producer of bentonite, with almost a one-quarter share of the world's production, followed by the United States and India. Total worldwide production was 24,400,000 metric tons of bentonite and 3,400,000 metric tons of fuller's earth. Most high-grade natural sodium bentonite is produced from the western United States in an area between

528-607: A clay veneer, and still others have a biological crust of algae or lichens . 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. Although most badland topography is natural, badlands have been produced artificially by destruction of vegetation cover, through overgrazing , acid rain , or acid mine drainage . The Cheltenham Badlands in Caledon, Ontario are an example of badlands produced by poor farming practices . In

594-413: A distinctive badlands topography . This is terrain in which water erosion has cut a very large number of deep drainage channels, separated by short, steep ridges ( interfluves ). Such a drainage system is said to have a very fine drainage texture, as measured by its drainage density . Drainage density is defined as the total length of drainage channels per unit area of land surface. Badlands have

660-742: A hideout for outlaws . There is a large badland area in Alberta , particularly in the valley of the Red Deer River , where Dinosaur Provincial Park is located, as well as in Drumheller , where the Royal Tyrrell Museum of Palaeontology is located. 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

726-670: A layer of unweathered shale. Badlands such as those found in the Mancos Shale , the Brule Formation , the Chadron Formation , and the Dinosaur Provincial Park can be generally said to fit this profile. In less arid regions, the regolith profile can vary considerably. Some badlands have no regolith layer whatsoever, capping instead in bare rock such as sandstone . Others have a regolith with

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792-424: A new trench elsewhere on the construction site. In addition, because the colloid is relatively impervious to water, a slurry wall can prevent the seepage of groundwater, which is useful in preventing the further spread of groundwater that has been contaminated by toxic material such as industrial waste. Plasticity is the property of clay that allows it to be manipulated and retain its shape without cracking after

858-416: A sealant since it provides a self-sealing, low- permeability barrier. It is used to line the base of landfills to prevent migration of leachate , for confining metal pollutants of groundwater , and for the sealing of subsurface disposal systems for spent nuclear fuel . Similar uses include making slurry walls , waterproofing of below-grade walls, and forming other impermeable barriers, e.g., to seal off

924-519: A soluble sodium salt such as sodium carbonate to wet bentonite, mixing well, and allowing time for the ion exchange to take place and water to remove the exchanged calcium. Some properties, such as viscosity and fluid loss of suspensions, of sodium-beneficiated calcium bentonite (or sodium-activated bentonite) may not be fully equivalent to those of natural sodium bentonite. For example, residual calcium carbonates (formed if exchanged cations are insufficiently removed) may result in inferior performance of

990-480: A sufficient hydraulic pressure in the well). Bentonite also curtails drilling fluid invasion by its propensity for aiding in the formation of mud cake . It plays an important role in the earth pressure balance and slurry shield variants of tunnel boring machines . Much of bentonite's usefulness in the drilling and geotechnical engineering industry comes from its unique rheological properties. Relatively small quantities of bentonite suspended in water form

1056-670: A terrain of lava flows that is unlike the eroded badlands of the White River. Badlands are generally unsuitable for agriculture, but attempts have been made to remediate badlands. For example, reforestation is being attempted in the Garbeta badlands of Eastern India. Revegetation and reforestation have been studied in the black marl badlands of the French Alps . Austrian black pine can become established and then be gradually replaced by native deciduous species. However,

1122-402: A very high drainage density of 48 to 464 kilometres per square kilometre (77 to 747 miles per square mile). The numerous deep drainage channels and high interfluves creates a stark landscape of hills , gullies , and ravines . In addition to a dense system of drainages and interfluves, badlands often contain buttes and hoodoos . These are formed by resistant beds of sandstone, which form

1188-431: A weak negative electrical charge, and this is neutralized by calcium or sodium cations that bind adjacent layers together, with a distance between layers of about 1 nanometer . Because the negative charge is weak, only a fraction of the possible cation sites on the surface of a TOT layer actually contain calcium or sodium. Water molecules can easily infiltrate between sheets and fill the remaining sites. This accounts for

1254-846: Is Toadstool Geologic Park in the Oglala National Grassland located in northwestern Nebraska . Dinosaur National Monument in Colorado and Utah are also badlands settings, along with several other areas in southern Utah, such as the Chinle Badlands in Grand Staircase–Escalante National Monument . A small badland called Hell's Half-Acre is present in Natrona County , Wyoming . Additional badlands also exist in various places throughout southwest Wyoming, such as near Pinedale and in

1320-449: Is a stub . You can help Misplaced Pages by expanding it . Badlands Badlands are found on every continent except Antarctica, being most common where there are unconsolidated sediments . They are often difficult to navigate by foot, and are unsuitable for agriculture. Most are a result of natural processes, but destruction of vegetation by overgrazing or pollution can produce anthropogenic badlands. Badlands are characterized by

1386-415: Is a high-charge TOT clay mineral, in which negatively charged sheets are bound relatively strongly by more numerous potassium cations , and so it is no longer a swelling clay and has few industrial uses. In contrast to the highly hydrated Na ions which act as "swellers" or "expanders" ions, poorly hydrated K ions behave as "collapsers" when exchanging with Na ions accessible in

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1452-484: 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, the Henry Mountains badlands show very little piping. The precise processes by which the erosion responses take place vary depending on the precise interbedding of the sedimentary material. However, it has been estimated that

1518-489: Is a useful adsorbent of ions in solution, as well as fats and oils. It is the main active ingredient of fuller's earth , probably one of the earliest industrial cleaning agents. It has significantly less swelling capacity than sodium bentonite. Calcium bentonite may be converted to sodium bentonite (termed sodium beneficiation or sodium activation) to exhibit many of sodium bentonite's properties by an ion exchange process. As commonly practiced, this means adding 5–10% of

1584-402: Is added to slow or prevent the settling of the glazes. It can also improve the consistency of application of glazes on porous biscuit-fired ware. Once a certain amount of glaze water has been absorbed by the biscuit the bentonite effectively clogs the pores and resists the absorption of further water resulting in a more evenly thick coat. Bentonite is used in industry and emergency response as

1650-441: Is an absorbent swelling clay consisting mostly of montmorillonite (a type of smectite ) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelling capacity than Ca-montmorillonite. Bentonite usually forms from the weathering of volcanic ash in seawater , or by hydrothermal circulation through the porosity of volcanic ash beds, which converts ( devitrification )

1716-447: Is applied to a type of claystone (a clay rock, not a clay mineral) composed mostly of montmorillonite (a clay mineral from the smectite group). It forms by devitrification of volcanic ash or tuff , typically in a marine environment. This results in a very soft, porous rock that may contain residual crystals of more resistant minerals, and which feels soapy or greasy to the touch. However, in commercial and industrial applications,

1782-465: 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 of bentonite clay further increases erodibility , as can rejuvenation of the drainage system from regional uplift , as occurred at Badlands National Park . In addition to surface erosion, badlands sometimes have well-developed piping , which

1848-478: Is described as low-charge TOT . This means that a crystal of montmorillonite consists of layers, each of which is made up of two T sheets bonded to either side of an O sheet. The T sheets are so called because each aluminium or silicon ion in the sheet is surrounded by four oxygen ions arranged as a tetrahedron. The O sheets are so called because each aluminium ion is surrounded by six oxygen or hydroxyl ions arranged as an octahedron. The complete TOT layer has

1914-562: Is often used in drilling mud for oil and gas wells and boreholes for geotechnical and environmental investigations. The property of swelling also makes sodium bentonite useful as a sealant, since it provides a self-sealing, low permeability barrier. It is used to line the base of landfills , for example. Bentonite is also part of the backfill material used at the nuclear Waste Isolation Pilot Project . Various surface modifications to sodium bentonite improve some rheological or sealing performance in geoenvironmental applications, for example,

1980-605: Is part of Navajo County encompasses numerous badlands that also abuts the Navajo Indian Reservation and is directly north of Joseph City, Arizona . Many dinosaurs are believed to be buried in the immediate area and exploration has been ongoing since the early 20th century. Among the Henry Mountains area in Utah, about 4,900 ft (1,500 m) above sea level, Cretaceous - and Jurassic -aged shales are exposed. Another popular area of badland formations

2046-804: Is the Roman gold mine of Las Médulas in northern Spain. The word badlands is a calque from the Canadian French phrase les mauvaises terres , as the early French fur traders called the White River badlands les mauvaises terres à traverser or 'bad lands to traverse', perhaps influenced by the Lakota people who moved there in the late 1700s and who referred to the terrain as mako sica , meaning 'bad land' or 'eroded land'. The term malpaís means 'badlands' in Spanish , but refers to

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2112-418: Is used as an ingredient in commercial and homemade clay bodies and ceramic glazes. It greatly increases the plasticity of clay bodies and decreases settling in glazes, making both easier to work with for most applications. The ionic surface of bentonite has a useful property in making a sticky coating on sand grains. When a small proportion of finely ground bentonite clay is added to hard sand and wetted,

2178-640: The Bridger Valley near the towns of Lyman and Mountain View , near the high Uintah Mountains . Pinnacles National Park in California also has areas of badlands, as does the Mojave Desert in eastern California . Badlands have become a popular trope inside various media, particularly westerns . Bentonite Bentonite ( / ˈ b ɛ n t ə n aɪ t / BEN -tə-nyte )

2244-845: The Putangirua Pinnacles , formed by the erosion of the conglomerate of an old alluvial fan – is located at the head of a small valley near the southern tip of the North Island . The Bardenas Reales near Tudela, Navarre , the Tabernas Desert in Tabernas, Almería , parts of the Granada Altiplano near Guadix and possibly Los Monegros in Aragon are examples of Spanish badlands. Turkey has extensive badlands, including Göreme National Park . In

2310-455: The annulus of a water well , to plug old wells. Bentonite can also be "sandwiched" between synthetic materials to create geosynthetic clay liners (GCLs) for the aforementioned purposes. This technique allows for more convenient transport and installation, and it greatly reduces the volume of bentonite required. It is also used to form barriers around newly planted trees to constrain the growth of its roots: in order to prevent damage to any of

2376-444: The caprock of the buttes and hoodoos. Badlands arise from a combination of an impermeable but easily eroded ground surface, sparse vegetation , and infrequent but heavy rainfall. The surface bedrock is typically mudrock , sometimes with evaporites , with only occasional beds of more resistant sandstone . Infrequent heavy rains lead to heavy erosional dissection. Where sudden precipitation cannot penetrate impermeable clays, it

2442-462: The volcanic glass ( obsidian , rhyolite , dacite ) present in the ash into clay minerals. In the mineral alteration process, a large fraction (up to 40–50 wt.%) of amorphous silica is dissolved and leached away, leaving the bentonite deposit in place. Bentonite beds are white or pale blue or green (traces of reduced Fe ) in fresh exposures, turning to a cream color and then yellow, red, or brown (traces of oxidized Fe ) as

2508-609: The North Island of New Zealand, in the Wellington region . Some 7 to 9 million years ago when sea levels were much higher, the Aorangi ranges were an island. As this landmass was eroded over time, large alluvial fans formed on its southern shores. Within a few million years however, sea levels rose again and the island was submerged. Since the ice ages , sea levels have receded, and the old alluvial fans have been exposed to

2574-598: The U.S., Makoshika State Park in Montana and Badlands National Park in South Dakota are examples of extensive badland formations. Also located in this region is Theodore Roosevelt National Park , a United States National Park composed of three geographically separated areas of badlands in western North Dakota named after former U.S. President Theodore Roosevelt . Petrified Forest National Park in Arizona which

2640-399: The active agent is uniformly dispersed and that pesticides and fertilizers are retained on the plants. Bentonite is used as a filler in a wide variety of products, including adhesives , cosmetics , paint , rubber , some greases , and soaps . It also acts as a stabilizer and extender in these products. The property of swelling on contact with water makes sodium bentonite useful as

2706-494: The addition of polymers. Sodium bentonite can be combined with elemental sulfur as fertilizer prills . These permit slow oxidation of the sulfur to sulfate , a plant nutrient needed for some crops like onions or garlic synthesizing a lot of organo-sulfur compounds, and maintain sulfate levels in rainfall-leached soil longer than either pure powdered sulfur or gypsum . Sulfur/bentonite pads with added organic fertilizers have been used for organic farming. Calcium bentonite

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2772-407: The application of locally sourced bentonite clays to degraded soils in the region. These applications were carried out in structured field trials. Applying bentonite clays effectively improved yields of forage sorghum grown under rain-fed conditions. Bentonite application also influenced the prices that farmers received for their crops. Production costs are higher, but due to higher production and

2838-439: The badlands of Badlands National Park erode at the relatively high rate of about one inch or 25 millimetres per year. The White River draining Badlands National Park was so named for its heavy load of bentonite clay eroded from the badlands. Badlands are partially characterized by their thin to nonexistent regolith layers. The regolith profiles of badlands in arid climates are likely to resemble one another. In these regions,

2904-469: The bentonite in geosynthetic liners. Illite is the main clay constituent of potash bentonite (a rock type also known as K-bentonite or potassium bentonite). K-bentonite is a term reserved to volcanic stratigraphy and tephrochronology and is related to the weathered clay rock type only. Illite, the clay mineral, is a potassium -rich phyllosilicate formed from the alteration of smectic clay in contact with groundwater rich in K ions. Illite

2970-597: The clay binds the sand particles into a moldable aggregate known as green sand used for making molds in sand casting . Some river deltas naturally deposit just such a blend of clay silt and sand, creating a natural source of excellent molding sand that was critical to ancient metalworking technology. Modern chemical processes to modify the ionic surface of bentonite greatly intensify this stickiness, resulting in remarkably dough-like yet strong casting sand mixes that stand up to molten metal temperatures. The same effluvial deposition of bentonite clay onto beaches accounts for

3036-651: The dominant clay species is illite (a non-swelling clay). However, in pure clay mineralogy, the term illite is more appropriate than "K-bentonite" (the "altered K-rock") because it is a distinct type of non-swelling clay while the commercial term bentonite implicitly refers to a swelling clay, a smectite (in the European and UK terminology), or a montmorillonite (in the US terminology). Sodium bentonite expands when wet, absorbing as much as several times its dry mass in water. Because of its excellent colloidal properties, it

3102-426: The early 1900s, the area was used for agricultural purposes, predominantly cattle grazing . Agricultural use ceased by 1931 and natural recovery of the majority of the property began. 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. An example of badlands created by mining

3168-525: The erosive forces of wind and water which have weathered away the conglomerate . In some places this conglomerate is protected from erosion by a cap of cemented silt or rock; this has resulted in the formation of spectacular pinnacles, many of which have prominent fluting caused by rainwater running down their sides during major storms. It is not known exactly how long the pinnacles have been forming but they are thought to be less than 125,000 years old; major erosion probably began 7,000 years ago and accelerated in

3234-454: The exposure is weathered further. As a swelling clay, bentonite has the ability to absorb large quantities of water, which increases its volume by up to a factor of eight. This makes bentonite beds unsuitable for building and road construction. However, the swelling property is used to advantage in drilling mud and groundwater sealants. The montmorillonite / smectite making up bentonite is an aluminium phyllosilicate mineral , which takes

3300-589: The form of microscopic platy grains. These give the clay a very large total surface area, making bentonite a valuable adsorbent . The plates also adhere to each other when wet. This gives the clay a cohesiveness that makes it useful as a binder and as an additive to improve the plasticity of kaolinite clay used for pottery . One of the first findings of bentonite was in the Cretaceous Benton Shale near Rock River, Wyoming . The Fort Benton Group , along with others in stratigraphic succession,

3366-494: The incidental use of inducing more rapid clarification of both red and white wines. Bentonite is also considered an effective low-cost adsorbent for the removal of chromium(VI) ions from aqueous solutions (contaminated wastewater). Bentonite is used in a variety of pet care items such as cat litter to absorb pet waste. It is also used to absorb oils and grease. Bentonite is used as an inert carrier for pesticides , fertilizers , and fire retardants . It helps ensure that

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3432-415: The interlayers space present between two TOT layers. Dehydrated K ions are preferentially located in between two face-to-face hexagonal cavities formed by six joined silica tetrahedra present at the surface of the basal plane of a TOT layer (see the corresponding figure showing an elementary TOT layer). Because dehydrated, these K ions are sometimes said to form inner-sphere bonds with

3498-691: The last 1,000 years with the deforestation of the area. The current erosion rate is approximately 1 cm per year. Part of the Paths of the Dead sequence in the film The Lord of the Rings: The Return of the King was filmed on location here, as was the opening sequence of Braindead . In December 2019, the approved official geographic name of the rocks was gazetted as "Pūtangirua Pinnacles". This Wellington Region -related geography article

3564-414: The nearby footpaths, parking lots, playgrounds, etc; or any of the surrounding underground infrastructures like the pipes, drainage systems, sewers, etc. Farmers use bentonite to seal retention ponds and line canals. High-purity calcium bentonite is treated with acid for use as a catalyst in cracking heavy petroleum fractions. Bentonite has been prescribed as a bulk laxative , and it is also used as

3630-454: The property of adsorbing relatively large amounts of protein molecules from aqueous solutions. Consequently, bentonite is uniquely useful in the process of winemaking , where it is used to remove excessive amounts of protein from white wines . Were it not for this use of bentonite, many or most white wines would precipitate undesirable flocculent clouds or hazes upon exposure to warm temperatures, as these proteins denature . It also has

3696-417: The quality of the food, clay farmers could afford to invest and grow more and better food, compared to nonclay-using farmers. Bentonite slurry walls (also known as diaphragm walls ) are used in construction, where the slurry wall is a trench filled with a thick colloidal mixture of bentonite and water. A trench that would collapse due to the hydraulic pressure in the surrounding soil does not collapse as

3762-496: The shaping force has been removed; clays with low plasticity are known as short or non-plastic . A small amount of bentonite added to clay can increase its plasticity, and hence ease forming of articles by some shaping techniques. However, bentonite typically contains minerals that affect the fired color of the mix, and its swelling properties can make such a mix prone to significant shrinkage and potential cracking as it dries. Ceramic glazes often contain bentonite. The bentonite

3828-406: The slurry balances the hydraulic pressure. Forms for concrete, and rebar, can be assembled in a slurry-filled trench, and then have concrete poured into the form. The liquid concrete being denser displaces the less-dense bentonite slurry and causes the latter to overflow from the trench. This displaced bentonite slurry is then channeled to a recycling unit from which it can subsequently be reused in

3894-406: The surrounding oxygen atoms present in the hexagonal cavity hosting them. It means there is no water molecule in between the K ion and the oxygen atoms attached to the silica tetrahedra (T). The main uses of bentonite are in drilling mud and as a binder , purifier, absorbent , and carrier for fertilizers or pesticides . As of around 1990, almost half of the US production of bentonite

3960-530: The swelling property of montmorillonite and other smectite clay minerals. The different types of bentonite are each named after the respective dominant cation. For industrial purposes, two main classes of bentonite are recognized: sodium and calcium bentonite. Sodium bentonite is the more valuable but calcium bentonite is more common. In stratigraphy and tephrochronology , completely devitrified (weathered volcanic glass) ash-fall beds are sometimes also referred to as "K-bentonites" (the illitized clay rock) when

4026-419: The term bentonite is used more generally to refer to any swelling clay composed mostly of smectite clay minerals, which includes montmorillonite. The undifferentiated reference to the weathered volcanic rock for the geologist or to the industrial mixture of swelling clays can be a source of confusion. The montmorillonite making up bentonite is an aluminium phyllosilicate mineral whose crystal structure

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4092-598: The time scale for this process is many decades. Badlands are found on all the continents except Antarctica . The presence of unconsolidated sediments is a strong control on their locations. The Valle de la Luna ("Valley of the Moon") is one of many examples of badland formations in midwestern Argentina . The Cheltenham Badlands are in Caledon, Ontario , not far from Canada's largest city Toronto . The Big Muddy Badlands in Saskatchewan gained notoriety as

4158-509: The upper layer (~1–5 cm or 0.4–2.0 in) is typically composed of silt , shale , and sand (a byproduct of the weathered 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

4224-631: The variety of plasticity of sand from place to place for building sand castles . Beach sand consisting of only silica and shell grains does not mold well compared to grains coated with bentonite clay. This is why some beaches are much better for building sandcastles than others. The self-stickiness of bentonite allows high-pressure ramming or pressing of the clay in molds to produce hard, refractory shapes, such as model rocket nozzles. Bentonites are used for decolorizing various mineral, vegetable, and animal oils. They are also used for clarifying wine, liquor, cider, beer, mead, and vinegar. Bentonite has

4290-521: Was named after Fort Benton, Montana , in the mid-19th century by Fielding Bradford Meek and F. V. Hayden of the U.S. Geological Survey. Bentonite has since been found in many other locations, including China and Greece (bentonite deposit of the Milos volcanic island in the Aegean Sea ). The total worldwide production of bentonite in 2018 was 20,400,000 metric tons. In geology, the term bentonite

4356-426: Was used as drilling mud. Minor uses include filler , sealant , and catalyst in petroleum refining . Calcium bentonite is sometimes marketed as fuller's earth , whose uses overlap with those of other forms of bentonite. Bentonite is used in drilling mud to lubricate and cool the cutting tools ( drill bit ), to remove cuttings, to stabilize the borehole walls, and to help prevent blowouts (by maintaining

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