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48-514: This type of cave was first formally described by Englishman Edwin Swift Balch in 1900, who suggested the French term glacieres should be used for them, even though the term ice cave was then, as now, commonly used to refer to caves simply containing year-round ice. Among speleologists , ice cave is the proper English term. A cavity formed within ice (as in a glacier) is properly called

96-867: A glacier cave . Ice caves occur as static ice caves, such as Peña Castil Ice Cave, and dynamic or cyclical ice caves, such as Eisriesenwelt . In most of the world, bedrock caves are thermally insulated from the surface and so commonly assume a near-constant temperature approximating the annual average temperature at the surface. In some cold environments, such as that surrounding Mount Erebus , average surface (and thus cave) temperatures are below freezing, and with surface water available in summer, ice caves are possible and are sometimes overlain by fumarolic ice towers . However, many ice caves exist in temperate climates, due to mechanisms that result in cave temperatures being colder than average surface temperatures where they formed. Cold traps : Certain cave configurations allow seasonal convection to import cold air from

144-400: A cave. Cave maps, called surveys , can be used to compare caves to each other by length, depth and volume, may reveal clues on speleogenesis , provide a spatial reference for further scientific study, and assist visitors with route-finding. Caves provide a home for many unique biota. Cave ecologies are very diverse, and not sharply distinct from surface habitats. Generally however, the deeper

192-549: A falls, so almost anything is possible given the right geological and hydrological setting. Waterfalls normally form in a rocky area due to erosion. After a long period of being fully formed, the water falling off the ledge will retreat, causing a horizontal pit parallel to the waterfall wall. Eventually, as the pit grows deeper, the waterfall collapses to be replaced by a steeply sloping stretch of river bed. In addition to gradual processes such as erosion, earth movement caused by earthquakes or landslides or volcanoes can lead to

240-421: A moisture-saturated cave may have an additional cooling effect due to the latent heat of evaporation . This may create a zone within the cave that is cooler than the rest of the cave. Because many caves have seasonally-reversing draughts, the corresponding warming of the cave through condensation in summer may occur at a different location within the cave, but in any event a moisture-saturated cave environment

288-465: A pioneering work on waterfalls. In 1942 Oscar von Engeln wrote of the lack of research on waterfalls: Waterfall sites more than any other geomorphic feature attract and hold the interest of the general public. Because they have such a popular approval waterfalls are not given serious attention by some students of systematic geomorphology. This attitude is not to be commended. Waterfalls are significant items for geomorphic investigation. As late as 1985

336-795: A role in many cultures, as religious sites and subjects of art and music. Many artists have painted waterfalls and they are referenced in many songs, such as those of the Kaluli people in Papua New Guinea . Michael Harner titled his study of the Jivaroan peoples of Ecuador The Jivaro: People of the Sacred Waterfalls. Artists such as those of the Hudson River School and J. M. W. Turner and John Sell Cotman painted particularly notable pictures of waterfalls in

384-603: A scholar felt that "waterfalls remain a very much neglected aspect of river studies". Studies of waterfalls increased dramatically in the second half of the 20th century. Numerous waterfall guidebooks exist, and the World Waterfall Database is a website cataloging thousands of waterfalls. Many explorers have visited waterfalls. European explorers recorded waterfalls they came across. In 1493, Christopher Columbus noted Carbet Falls in Guadeloupe , which

432-402: A sinkhole, frogs swept into a cave by a flash flood, etc. The two factors that limit cave ecologies are generally energy and nutrients. To some degree moisture is always available in actively forming Karst caves. Cut off from the sunlight and steady deposition of plant detritus, caves are poor habitats in comparison with wet areas on the surface. Most of the energy in cave environments comes from

480-506: A stream or river flowing into a glacier continues to flow into a valley after the glacier has receded or melted. The large waterfalls in Yosemite Valley are examples of this phenomenon, which is referred to as a hanging valley . Another reason hanging valleys may form is where two rivers join and one is flowing faster than the other. When warm and cold water meets by a gorge in the ocean, large underwater waterfalls can form as

528-408: Is a type of stream pool formed at the bottom of a waterfall. A waterfall may also be referred to as a "foss" or "force". Waterfalls are commonly formed in the upper course of a river where lakes flow into valleys in steep mountains. A river sometimes flows over a large step in the rocks that may have been formed by a fault line . Waterfalls can occur along the edge of a glacial trough , where

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576-824: Is also no agreement how to measure the height of a waterfall, or even what constitutes one. Angel Falls in Venezuela is the tallest waterfall in the world , the Khone Phapheng Falls in Laos are the widest, and the Inga Falls on the Congo River are the biggest by flow rate , while the Dry Falls in Washington are the largest confirmed waterfalls ever. The highest known subterranean waterfall

624-524: Is cooler than the cave air. Some cold traps may ensnare surface snow and shade it from the summer sun ’s rays , which may further contribute to the colder cave temperature. Permafrost : Even temperate environments can include pockets of bedrock that are below freezing year round, a condition called permafrost . For example, winter wind and an absence of snow cover may allow freezing deep enough to be protected from summer thaw, particularly in light-colored rock that does not readily absorb heat. Although

672-466: Is fractured or otherwise more erodible. Hydraulic jets and hydraulic jumps at the toe of a falls can generate large forces to erode the bed, especially when forces are amplified by water-borne sediment. Horseshoe-shaped falls focus the erosion to a central point, also enhancing riverbed change below a waterfall. A process known as "potholing" involves local erosion of a potentially deep hole in bedrock due to turbulent whirlpools spinning stones around on

720-426: Is highly favorable for the growth of microbes . Microbial assemblages in caves include archaea , bacteria , fungi and other micro- eukaryotes , these highly adapted microbial communities represent the living-backbone of cave ecosystems and play a key role in shaping structures and sustaining trophic networks. The creation of an accurate, detailed map is one of the most common technical activities undertaken within

768-551: Is likely to experience much more evaporative cooling than condensative warming. Different freezing mechanisms result in visually and structurally distinct types of perennial cave ice. Ponded water : Surface water that collects and ponds in a cave before freezing will form a clear ice mass, and can be tens of metres thick and of great age. Large ice masses are plastic and can slowly flow in response to gravity or pressure from further accumulations. Sculpting from air flow and sublimation may reveal ancient accumulation bands within

816-521: Is the scientific study of caves and other karst features, as well as their composition , structure, physical properties , history, ecology , and the processes by which they form ( speleogenesis ) and change over time (speleomorphology). The term speleology is also sometimes applied to the recreational activity of exploring caves, but this is more properly known as caving , potholing (British English), or spelunking (United States and Canadian English). Speleology and caving are often connected, as

864-804: Is undoubtedly presented by the continent of Africa, the 'darkness' of which is almost entirely due to this cause." Waterfalls are often visited by people simply to see them. Hudson theorizes that they make good tourism sites because they are generally considered beautiful and are relatively uncommon. Activities at waterfalls can include bathing, swimming, photography, rafting , canyoning , abseiling , rock climbing , and ice climbing . Waterfalls can also be sites for generating hydroelectric power and can hold good fishing opportunities. Wealthy people were known to visit areas with features such as waterfalls at least as early as in Ancient Rome and China . However, many waterfalls were essentially inaccessible due to

912-477: The Gocta Cataracts were first announced to the world in 2006. Waterfalls can pose major barriers to travel. Canals are sometimes built as a method to go around them, other times things must be physically carried around or a railway built . In 1885, the geographer George Chisholm wrote that, "The most signal example of the effect of waterfalls and rapids in retarding the development of civilisation

960-541: The black swift and white-throated dipper . These species preferentially nest in the space behind the falling water, which is thought to be a strategy to avoid predation. Some waterfalls are also distinct in that they do not flow continuously. Ephemeral waterfalls only flow after a rain or a significant snowmelt. Waterfalls can also be found underground and in oceans. The geographer Andrew Goudie wrote in 2020 that waterfalls have received "surprisingly limited research." Alexander von Humboldt wrote about them in

1008-400: The 1820s. There is no name for the specific field of researching waterfalls, and in the published literature been described as "scattered", though it is popular to describe studying waterfalls as "waterfallology". An early paper written on waterfalls was published in 1884 by William Morris Davis , a geologist known as the "father of American geography". In the 1930s Edward Rashleigh published

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1056-444: The 18th century, they have received increased attention as tourist destinations, sources of hydropower , and—particularly since the mid-20th century—as subjects of research. A waterfall is generally defined as a point in a river where water flows over a steep drop that is close to or directly vertical. In 2000 Mabin specified that "The horizontal distance between the positions of the lip and plunge pool should be no more than c 25% of

1104-703: The 19th century. One of the versions of the Shinto purification ceremony of misogi involves standing underneath a waterfall in ritual clothing. In Japan the Nachi Falls are a site of pilgrimage, as are falls near Tirupati , India, and the Saut-d'Eau , Haiti. The Otavalos use Piguchi waterfall as part of the Churru ritual which serves as a coming of age ceremony. Many waterfalls in Africa were places of worship for

1152-426: The base of the waterfall by abrasion , creating a deep plunge pool in the gorge downstream. Streams can become wider and shallower just above waterfalls due to flowing over the rock shelf, and there is usually a deep area just below the waterfall because of the kinetic energy of the water hitting the bottom. However, a study of waterfalls systematics reported that waterfalls can be wider or narrower above or below

1200-441: The bed, drilling it out. Sand and stones carried by the watercourse therefore increase erosion capacity. This causes the waterfall to carve deeper into the bed and to recede upstream. Often over time, the waterfall will recede back to form a canyon or gorge downstream as it recedes upstream, and it will carve deeper into the ridge above it. The rate of retreat for a waterfall can be as high as one-and-a-half metres per year. Often,

1248-418: The cave becomes, the more rarefied the ecology. Cave environments fall into three general categories: Cave organisms fall into three basic classes: There are also so-called accidental trogloxenes which are surface organisms that enter caves for no survival reason. Some may even be troglophobes (“cave haters”), which cannot survive in caves for any extended period. Examples include deer which fell through

1296-621: The cave walls and ceiling. Needle ice : Infiltrating water that freezes within the bedrock can sometimes be forced into the cave passage. Intrusions : The weight of a surface glacier perched atop a cave entrance can force glacial ice a short distance into the cave. The only known examples of this phenomenon are the several 'ice plugs' at the back of Castleguard Cave in Alberta . Speleologist Speleology (from Ancient Greek σπήλαιον ( spḗlaion )  'cave' and -λογία ( -logía )  'study of')

1344-401: The cold water rushes to the bottom. The caprock model of waterfall formation states that the river courses over resistant bedrock , erosion happens slowly and is dominated by impacts of water-borne sediment on the rock, while downstream the erosion occurs more rapidly. As the watercourse increases its velocity at the edge of the waterfall, it may pluck material from the riverbed, if the bed

1392-580: The concept of speleology as a distinct area of study. In 1895 Martel founded the Société de Spéléologie , the first organization devoted to cave science in the world. Other early speleologists include Herbert E. Balch . An international speleological congress was proposed at a meeting in Valence-sur-Rhone , France in 1949 and first held in 1953 in Paris . The International Union of Speleology (UIS)

1440-652: The decomposition of the materials can happen as well. A speleothem is a geological formation by mineral deposits that accumulate over time in natural caves . Speleothems most commonly form in calcareous caves due to carbonate dissolution reactions. They can take a variety of forms, depending on their depositional history and environment. Their chemical composition, gradual growth, and preservation in caves make them useful paleoclimatic proxies. Caves have an absence of stable temperature , high relative humidity , low rates of evaporation and limited supply of organic material , which help in creating an environment which

1488-568: The disasters that can devastate or destroy underground biological communities. Speleologists also work with archaeologists in studying underground ruins, tunnels, sewers and aqueducts, such as the various inlets and outlets of the Cloaca Maxima in Rome . Waterfall A waterfall is any point in a river or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over

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1536-623: The edge of a tabular iceberg or ice shelf . Waterfalls can be formed in several ways, but the most common method of formation is that a river courses over a top layer of resistant bedrock before falling onto softer rock, which erodes faster, leading to an increasingly high fall. Waterfalls have been studied for their impact on species living in and around them. Humans have had a distinct relationship with waterfalls since prehistory, travelling to see them, exploring and naming them. They can present formidable barriers to navigation along rivers. Waterfalls are religious sites in many cultures. Since

1584-678: The environment of the waterfall itself. A 2012 study of the Agbokim Waterfalls , has suggested that they hold biodiversity to a much higher extent than previously thought. Waterfalls also affect terrestrial species. They create a small microclimate in their immediate vicinity characterized by cooler temperatures and higher humidity than the surrounding region, which may support diverse communities of mosses and liverworts . Species of these plants may have disjunct populations at waterfall zones far from their core range. Waterfalls provide nesting cover for several species of bird, such as

1632-415: The formation of waterfalls. Waterfalls are an important factor in determining the distribution of lotic organisms such as fish and aquatic invertebrates, as they may restrict dispersal along streams. The presence or absence of certain species can have cascading ecological effects, and thus cause differences in trophic regimes above and below waterfalls. Certain aquatic plants and insects also specialize in

1680-506: The ice. Accumulated snow : Compressed under the weight of ongoing accumulations, snow sliding or falling into a cave entrance may eventually form ice that is coarsely crystalline, akin to glacier ice. True underground glaciers are rare. Ice formations : Water that freezes before ponding may form icicles , ice- stalagmites , ice columns or frozen waterfalls . Airborne moisture (water vapor) : Freezing vapor can form frost crystals, frost feathers and two-dimensional ice plates on

1728-661: The native peoples and got their names from gods in the local religion. "In Chinese tradition, the waterfall represents" the season of autumn , yin , and the Chinese dragon 's power over water that comes from the former two. There are thousands of waterfalls in the world, though no exact number has been calculated. The World Waterfall Database lists 7,827 as of 2013, but this is likely incomplete; as noted by Hudson, over 90% of their listings are in North America. Many guidebooks to local waterfalls have been published. There

1776-416: The physical skills required for in situ study are the same. Speleology is a cross-disciplinary field that combines the knowledge of chemistry , biology , geology , physics , meteorology , and cartography to develop portraits of caves as complex, evolving systems. Before modern speleology developed, John Beaumont wrote detailed descriptions of some Mendip caves in the 1680s. The term speleology

1824-440: The portion of a cave within this permafrost zone will be below freezing, permafrost generally does not allow water percolation , so ice formations are often limited to crystals from vapor , and deeper cave passages may be arid and completely ice-free. Ice caves in permafrost need not be cold-traps (although some are), provided they do not draught significantly in summer. Evaporative cooling : In winter, dry surface air entering

1872-728: The rise of Romanticism , and increased importance of hydropower with the Industrial Revolution . European explorers often preferred to give waterfalls names in their own language; for instance, David Livingstone named Victoria Falls after Queen Victoria , though it was known by local peoples as Mosi-oa-Tunya. Many waterfalls have descriptive names which can come from the river they are on, places they are near, their features, or events that happened near them. Some countries that were colonized by European nations have taken steps to return names to waterfalls previously renamed by European explorers. Exploration of waterfalls continues;

1920-504: The rock stratum just below the more resistant shelf will be of a softer type, meaning that undercutting due to splashback will occur here to form a shallow cave-like formation known as a rock shelter under and behind the waterfall. Eventually, the outcropping , more resistant cap rock will collapse under pressure to add blocks of rock to the base of the waterfall. These blocks of rock are then broken down into smaller boulders by attrition as they collide with each other, and they also erode

1968-403: The surface in winter, but not warm air in summer. A typical example is an underground chamber located below a single entrance. In winter, cold dense air settles into the cave, displacing any warmer air which rises and exits the cave. In summer, the cold cave air remains in place as the relatively warm surface air is lighter and cannot enter. The cave will only exchange air when the surface air

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2016-419: The surplus of the ecosystems outside. One major source of energy and nutrients in caves is dung from trogloxenes, most of which is deposited by bats. Other sources are mentioned above. Cave ecosystems are very fragile. Because of their rarity and position in the ecosystem they are threatened by a large number of human activities. Dam construction, limestone quarrying, water pollution and logging are just some of

2064-546: The treacherous terrain surrounding them until improvements began to be made such as paths to the falls, becoming common across the United Kingdom and America in the 1800s and continuing through the 1900s and into the 21st century. Remote waterfalls are now often visited by air travel. Human development has also threatened many waterfalls. For instance, the Guaíra Falls , once one of the most powerful waterfalls in

2112-423: The waterfall height." There are various types and methods to classify waterfalls. Some scholars have included rapids as a subsection. What actually constitutes a waterfall continues to be debated. Waterfalls are sometimes interchangeably referred to as "cascades" and "cataracts", though some sources specify a cataract as being a larger and more powerful waterfall and a cascade as being smaller. A plunge pool

2160-677: The world, were submerged in 1982 by a human-made dam, as were the Ripon Falls in 1952. Conversely, other waterfalls have seen significantly lower water levels as a result of diversion for hydroelectricity , such as the Tyssestrengene in Norway. Development of the areas around falls as tourist attractions has also destroyed the natural scene around many of them. Waterfalls are included on thirty-eight World Heritage Sites and many others are protected by governments. Waterfalls play

2208-563: Was coined by Émile Rivière in 1890. Prior to the mid-nineteenth century the scientific value of caves was considered only in its contribution to other branches of science, and cave studies were considered part of the larger disciplines of geography , geology or archaeology . Very little cave-specific study was undertaken prior to the work of Édouard-Alfred Martel (1859–1938), the 'father of modern speleology', who through his extensive and well-publicised cave explorations introduced in France

2256-608: Was founded in 1965. The growth of speleology is directly linked with that of the sport of caving , both because of the stimulation of public interest and awareness, and the fact that most speleological field-work has been conducted by sport cavers . Karst is a landscape that has limestone underneath which has been eroded. Caves are usually formed through chemical corrosion via a process of dissolution . Corrosion has several ways of doing this, it can be on carbonate rocks through chemical reactions, in gypsum and rock salt it can happen physically, and in silicate rocks and warm climate

2304-551: Was likely the first waterfall Europeans recorded seeing in the Americas. In the late 1600s, Louis Hennepin visited North America, providing early descriptions of Niagara Falls and the Saint Anthony Falls . The geographer Brian J. Hudson argues that it was uncommon to specifically name waterfalls until the 1700s. The trend of Europeans specifically naming falls was in tandem with increased scientific focus on nature,

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