Jeju Volcanic Island and Lava Tubes
The Jeju Volcanic Island and Lava Tubes is a World Heritage Site in South Korea. Jeju known as Jejudo, is a volcanic island, 130 kilometers from the southern coast of the Korean Peninsula; the largest island and smallest province in South Korea, the island has a surface area of 1,846 square kilometers. A central feature of Jeju is Hallasan, the tallest mountain in South Korea and a dormant volcano, which rises 1,950 meters above sea level; the main volcano includes 360 satellite volcanoes. Volcanic activity on Jeju began in the Cretaceous and lasted until the early Tertiary period; the most recent eruptions are estimated to be about 5,000 years ago, which puts the volcano into the active classification, meaning eruptions in the last 10,000 years. The designation as active is not agreed by all, as more monitoring and study are needed to better understand the volcano; the island is covered in volcanic rock and volcanic soil produced by Hallasan. Baengnokdam, the crater, lake in it are located at the peak of Hallasan, formed over 25,000 years ago.
Jeju is scientifically valuable for its extensive system of lava tubes. These natural conduits through which magma once flowed are now empty caves that are some of the largest in the world; the caves provide opportunities for scientific research and are popular tourist destinations. Off the shores of the city of Seogwipo are a vast belt of pillar-shaped rocks that are examples of the natural beauty of Jeju. Shellfish and animal fossils discovered in this area are very valuable as scientific resources. Beom Island and Mun Island off the city seacoast, are well preserved and scenic areas; the variety of animal and plant species on Jeju is an important reason for its value as a natural reserve. Half of all Korean vascular plants grow on the island while another 200 species of plants indigenous to Korea have been transported here. However, half of these species face extinction; the polar plants which came from the south during a glacial period and inhabit the peak of Jeju is one example. Other plants in the subtropical forest and lower regions of the island are endangered.
Hallasan is located in the central part of the island. Since 1966, any area 800 meters above sea level has been designated as a nature reserve; the park is unspoilt nature with hiking paths and park managerial facilities being the only man-made modifications in the area. The flora at the Mt. Halla National Park is unique. 1,565 vascular plant species have been recorded in the area thus far and is the highest number of plants in any mountain, 33 which are endemic to the island. Unlike most other Korean mountain environments, Hallsan has a unique vertical distribution of plants in three different zones: the subtropic and frigid zones. Over 17 mammals, 198 types of birds, 8 types of amphibians, 8 types of reptiles, 947 insect species have been catalogued in the nature reserve. Endangered species include the Capreolus capreolus pygargus and Felis bengalensis Manchuria, a resident population of Indo-Pacific bottlenose dolphins and finless porpoises; the island and adjacent waters had been migration colliders and resting areas for large whales such as western gray whales, North Pacific right whales, humpback whales, blue whales and fin whales.
Now extinct Japanese sea lions might have colonized on the island as well. Some pinnipeds still occur occasionally. Since the island was last connected to the Korean Peninsula 10,000 years ago, animals endemic to the island appeared at that time and this separation from the mainland is of biological significance. A famous part of the Mt. Halla Nature Reserve is the Pillemot Cave, a site dating to the Paleolithic period; the caves are significant because of the archaeological remains found there. Archaeological evidence from the cave suggests that people have occupied the island since the Paleolithic period. List of Korea-related topics World Heritage Sites in South Korea UNESCO World Heritage Site Jeju Volcanic Island and Lava Tubes, UNESCO World Heritage in Korea
A stalactite is a type of formation that hangs from the ceiling of caves, hot springs, or manmade structures such as bridges and mines. Any material, soluble, can be deposited as a colloid, or is in suspension, or is capable of being melted, may form a stalactite. Stalactites may be composed of lava, mud, pitch, sand and amberat. A stalactite is not a speleothem, though speleothems are the most common form of stalactite because of the abundance of limestone caves; the corresponding formation on the floor of the cave is known as a stalagmite. The most common stalactites are speleothems, they form through deposition of calcium carbonate and other minerals, precipitated from mineralized water solutions. Limestone is the chief form of calcium carbonate rock, dissolved by water that contains carbon dioxide, forming a calcium bicarbonate solution in underground caverns; the chemical formula for this reaction is: CaCO3 + H2O + CO2 → Ca2This solution travels through the rock until it reaches an edge and if this is on the roof of a cave it will drip down.
When the solution comes into contact with air the chemical reaction that created it is reversed and particles of calcium carbonate are deposited. The reversed reaction is: Ca2 → CaCO3 + H2O + CO2An average growth rate is 0.13 mm a year. The quickest growing stalactites are those formed by a constant supply of slow dripping water rich in calcium carbonate and carbon dioxide, which can grow at 3 mm per year; the drip rate must be slow enough to allow the CO2 to degas from the solution into the cave atmosphere, resulting in deposition of CaCO3 on the stalactite. Too fast a drip rate and the solution, still carrying most of the CaCO3, falls to the cave floor where degassing occurs and CaCO3 is deposited as a stalagmite. All limestone stalactites begin with a single mineral-laden drop of water; when the drop falls, it deposits the thinnest ring of calcite. Each subsequent drop that forms and falls deposits another calcite ring; these rings form a narrow, hollow tube known as a "soda straw" stalactite.
Soda straws can grow quite long, but are fragile. If they become plugged by debris, water begins flowing over the outside, depositing more calcite and creating the more familiar cone-shaped stalactite; the same water drops that fall from the tip of a stalactite deposit more calcite on the floor below resulting in a rounded or cone-shaped stalagmite. Unlike stalactites, stalagmites never start out as hollow "soda straws". Given enough time, these formations can meet and fuse to create pillars of calcium carbonate known as a "column". Stalactite formation begins over a large area, with multiple paths for the mineral rich water to flow; as minerals are dissolved in one channel more than other competing channels, the dominant channel begins to draw more and more of the available water, which speeds its growth resulting in all other channels being choked off. This is one reason; the larger the formation, the greater the interformation distance. Another type of stalactite is formed in lava tubes; the mechanism of formation is the deposition of material on the ceilings of caves, however with lava stalactites formation happens quickly in only a matter of hours, days, or weeks, whereas limestone stalactites may take up to thousands of years.
A key difference with lava stalactites is that once the lava has ceased flowing, so too will the stalactites cease to grow. This means; the generic term lavacicle has been applied to lava stalactites and stalagmites indiscriminately and evolved from the word icicle. Like limestone stalactites, they can leave lava drips on the floor that turn into lava stalagmites and may fuse with the corresponding stalactite to form a column. Shark tooth stalactites, it may begin as a small driblet of lava from a semi-solid ceiling, but grows by accreting layers as successive flows of lava rise and fall in the lava tube and recoating the stalactite with more material. They can vary from a few millimeters to over a meter in length. Splash stalactites As lava flows through a tube, material will be splashed up on the ceiling and ooze back down, hardening into a stalactite; this type of formation results in a irregularly shaped stalactite, looking somewhat like stretched taffy. They may be of a different color than the original lava that formed the cave.
Tubular lava stalactites When the roof of a lava tube is cooling, a skin will form that traps semi-molten material inside. Trapped gases force lava to extrude out through small openings that result in hollow, tubular stalactites analogous to the soda straws formed as depositional speleothems in solution caves, The longest known is 2 meters in length; these are common in Hawaiian lava tubes and are associated with a drip stalagmite that forms below as material is carried through the tubular stalactite and piles up on the floor beneath. Sometimes the tubular form collapses near the distal end, most when the pressure of escaping gases decreased and still-molten portions of the stalactites deflated and cooled; these tubular stalactites will acquire a twisted, vermiform appearance as bits of lava crystallize and force the flow in different directions. These tubular lava helictites may be influenced by air
Cave popcorn, or coralloids, are small nodes of calcite, aragonite or gypsum that form on surfaces in caves limestone caves. They are a common type of speleothem; the individual nodules of cave popcorn range in size from 5 to 20 mm and may be decorated by other speleothems aragonite needles or frostwork. The nodules tend to grow in the sides of other speleothems; these clusters may terminate in either an upward or downward direction, forming a stratographic layer. When they terminate in a downward direction, they may appear as flat bottomed formations known as trays. Individual nodes of popcorn can assume a variety of shapes from round to flattened ear or button like shapes; the color of cave popcorn is white, but various other colors are possible depending on the composition. Cave popcorn can form by precipitation. Water seeping through limestone walls or splashing onto them leaves deposits when CO2 loss causes its minerals to precipitate; when formed in this way, the resultant nodules have the characteristics of small balls of flowstone.
Cave popcorn can form by evaporation in which case it is chalky and white like edible popcorn. In the right conditions, evaporative cave popcorn may grow on the windward side of the surface to which it is attached or appear on the edges of projecting surfaces. Popcorn can occur on concrete structures outside the cave environment. Calthemite coralloids occur in "artificial caves" such as mines or railway or vehicle tunnels were there is a source of lime, mortar or cement from which the calcium ions can be leached. Coralloids can form by a number of different methods in caves. Due to solution evaporation, deposition of calcium carbonate occurs; the resulting coralloids are chalky with a cauliflower appearance. The Virtual Cave's page on cave popcorn The Virtual Cave's page on coralloids Underground Adventures Kids page on popcorn National Park Service page on popcorn
A lava tube is a natural conduit formed by flowing lava which moves beneath the hardened surface of a lava flow. Tubes can drain lava from a volcano during an eruption, or can be extinct, meaning the lava flow has ceased, the rock has cooled and left a long cave. A lava tube is a type of lava cave formed when a low-viscosity lava flow develops a continuous and hard crust, which thickens and forms a roof above the still-flowing lava stream. Tubes form in one of two ways: either by the crusting over of lava channels, or from pāhoehoe flows where the lava is moving under the surface. Lava leaves the point of eruption in channels; these channels tend to stay hot as their surroundings cool. This means they develop walls around them as the surrounding lava cools and/or as the channel melts its way deeper; these channels can get deep enough to crust over, forming an insulating tube that keeps the lava molten and serves as a conduit for the flowing lava. These types of lava tubes tend to be closer to the lava eruption point.
Farther away from the eruption point, lava can flow in an unchanneled, fan-like manner as it leaves its source, another lava tube leading back to the eruption point. Called pāhoehoe flows, these areas of surface-moving lava cool, forming either a smooth or rough, ropy surface; the lava continues to flow this way. At this point, the subsurface lava is still hot enough to break out at a point, from this point the lava begins as a new "source". Lava flows from the previous source to this breakout point as the surrounding lava of the pāhoehoe flow cools; this forms an underground channel. A broad lava-flow field consists of a main lava tube and a series of smaller tubes that supply lava to the front of one or more separate flows; when the supply of lava stops at the end of an eruption or lava is diverted elsewhere, lava in the tube system drains downslope and leaves empty caves. Such drained tubes exhibit step marks on their walls that mark the various depths at which the lava flowed, known as flow ledges or flow lines depending on how prominently they protrude from the walls.
Lava tubes have pāhoehoe floors, although this may be covered in breakdown from the ceiling. A variety of speleothems may be found in lava tubes including a variety of stalactite forms known as lavacicles, which can be of the splash, shark tooth, or tubular variety. Lavacicles are the most common of lava tube speleothems. Drip stalagmites may form under tubular lava stalactites, the latter may grade into a form known as a tubular lava helictite. A runner is a bead of lava, extruded from a small opening and runs down a wall. Lava tubes may contain mineral deposits that most take the form of crusts or small crystals, less as stalactites and stalagmites. Lava tubes can be up to 14–15 metres wide, though are narrower, run anywhere from 1–15 metres below the surface. Lava tubes can be long. A lava tube system in Kiama, consists of over 20 tubes, many of which are breakouts of a main lava tube; the largest of these lava tubes is 2 meters in diameter and has columnar jointing due to the large cooling surface.
Other tubes have radial jointing features. The tubes are infilled due to the low slope angle of emplacement. By far the largest known lava tubes in the Solar System are on Venus. Lunar lava tubes have been discovered and have been studied as possible human habitats, providing natural shielding from radiation. Martian lava tubes are associated with innumerable lava flows and lava channels on the flanks of Olympus Mons. Collapsed lava tubes are visible as chains of pit craters, broad lava fans formed by lava emerging from intact, subsurface tubes are common. Iceland Raufarhólshellir Surtshellir – For a long time, this was the longest known lava tube in the world. Kenya Leviathan Cave – At 12.5 kilometres, it is the longest lava tube in Africa. Portugal Gruta das Torres – Lava tube system of the Azores. South Korea Manjang Cave – more than 8 kilometers long, located in Jeju Island, is a popular tourism spot. Spain Cueva de los Verdes – Lava tube system. Lanzarote, Canary Islands. United States Kazumura Cave, Hawaii – Not only the world's most extensive lava tube, but at 40.7 miles has the greatest linear extent of any cave known.
Lava River Cave in Oregon's Newberry National Volcanic Monument – Newberry National Volcanic Monument Ape Cave, Washington – May be the third longest lava tube in the continental United States. Caving – Recreational pastime of exploring cave systems Geology of the Moon – Structure and composition of the Moon Lava cave – Cave formed in volcanic rock one formed via volcanic processes Mars habitat Speleology – Science of cave and karst systems Speleothem – A structure formed in a cave by the deposition of minerals from water
A helictite is a speleothem found in a limestone cave that changes its axis from the vertical at one or more stages during its growth. Helictites have a angular form that looks as if they were grown in zero gravity, they are most the result of capillary forces acting on tiny water droplets, a force strong enough at this scale to defy gravity. Helictites are the most delicate of cave formations, they are made of needle-form calcite and aragonite. Helictite forms have been described in several types: ribbon helictites, rods, butterflies, "hands", curly-fries, "clumps of worms", they have radial symmetry. They can be crushed or broken by the slightest touch; because of this, helictites are seen within arm's reach in tourist caves. Timpanogos Cave National Monument in Utah has one of the largest collections of these formations in the world. Large numbers are in the Jenolan Caves in Australia and in the Pozalagua Cave in Karrantza, Spain. A remarkable suite of helictites occurs in Asperge Cave, France.
The growth of helictites is still quite enigmatic. To this day, there has been no satisfactory explanation for. Formation by capillary forces is the most theory, but another theory based on wind formation is viable; the most theory explains helictites as a result of capillary forces. If the helictite has a thin central tube where the water flows like it does in straws, capillary forces would be able to transport water against gravity; this theory was inspired by some hollow helictites. However, the majority of helictites are not hollow. Despite this, droplets can be drawn to the tips of existing structures and deposit their calcite load anywhere thereon; this can lead to the curling structures seen in many helictites. Another theory names the wind in the cave as main reason for the strange look. Drops hanging on a stalactite are blown to one side, so the dripstone grows in that direction. If the wind changes, the direction of growth changes too. However, this theory is problematic, because wind directions change often.
The wind in caves depends on air pressure changes outside. The wind direction changes as as the weather conditions outside change, but the dripstones grow slowly – several centimeters in 100 years – meaning that the wind direction would have to stay steady for long periods of time, changing for every fragment of a millimeter of growth. A second problem with this theory is that many caves with helictites have no natural entrance where wind could enter. Another theory, proposed is that changing geological pressure causing stresses on the crystals at the base alters the piezo electrostatic potential and causes particle deposition to be oriented in some relationship to the prevailing pressure orientation. A recent theory, supported by observation, is that a prokaryotic bacterial film provides a nucleation site for mineralization process. A helictite starts its growth as a tiny stalactite; the direction of the end of the straw may wander, twist like a corkscrew, or the main part may form while small helictites pop out of its side like rootlets or fishhooks.
In some caves, helictites cluster together and form bushes as large as six feet tall. These bushes grow from the floor of the cave; when helictites are found on cave floors, they are referred to as heligmites, though there is debate as to whether this is a genuine subcategory. For an unknown reason, when the chemical composition of the water is altered, the single crystal structure can change from a cylindrical shape to a conical one. In some of these cases, each crystal fits into the prior one like an inverted stack of ice cream cones. Anthodite The Virtual Cave: Helictites Microbial mediation of complex subterranean mineral structures The Virtual Cave: Helictites Helictite or Eccentric? Does crystal splitting play a part in the curvature of helictites? By George W. Moore, Journal of Cave and Karst Studies, v. 62, p. 37
Seongsan Ilchulbong called ‘Sunrise Peak’, is an archetypal tuff cone formed by hydrovolcanic eruptions upon a shallow seabed about 5 thousand years ago. Situated on the eastern seaboard of Jeju Island and said to resemble a gigantic ancient castle, this tuff cone is 182 meters high, has a preserved bowl-like crater and displays diverse inner structures resulting from the sea cliff; these features are considered to be of geologic worth, providing information on eruptive and depositional processes of hydromagmatic volcanoes worldwide as well as past volcanic activity of Seongsan Ilchulbong itself. Seongsan Ilchulbong Tuff Cone was formed by Surtseyan-type hydrovolcanic activity upon a shallow seabed about 5,000 years ago when the sea level was same as the present. Most volcanic cones or oreums were formed by piles of scoria cones which are created by Hawaiian eruptions or Strombolian eruptions, but Seongsan Ilchulbong Tuff Cone and a few other oreums on Jeju Island were hydromagmatic volcanoes which were made by piles of volcanic ash, the interaction of hot ascending magma and seawater or ground water.
Seongsan Ilchulbong Tuff Cone is 180 meters high, its crater is about 600 meters in diameter. It is 90 meters from sea level to the crater floor. Seongsan Ilchulbong Tuff Cone erupted in moist and sticky conditions allowing a lot of water to permeate into the volcanic vent, making the diverse depositional features of a wet eruption; the wet hydrovolcanic activity continued until the end of the eruption. The tuff has a bowl-like crater unfilled by scoria or lava. Except for the northwestern park, the Seongsan Ilchulbong Tuff Cone forms a steep cliff because of the resultant wave following its eruptions. Through these eruptions, Seongsan Ilchulbong Tuff Cone shows a perfect cross section from the intracrater strata to the marginal strata, its diverse geological structures are considered to have great geological importance because they may be used to interpret not only the past volcanic activity of the Seongsan Ilchulbong Tuff Cone but eruptive and depositional processes of hydromagmatic volcanoes worldwide.
There are numerous hydromagmatic volcanoes similar to the Seongsan Ilchulbong, but there are no other known hydromagmatic volcanoes with a well-preserved tuff cone and diverse internal structures along a sea cliff. Because of these scientific values and remarkable scenery, Seongsan Ilchulbong Tuff Cone was able to be designated as a UNESCO World Natural Heritage site and it is worth preserving permanently as a natural heritage of humankind; the Seongsan Ilchulbong Tuff Cone’s flora is composed of 222 taxa. There are 6 rare plant species: a fern, Crypsinus hastatus, an orchid, Neofinetia falcata, two parasitic plants, Aeginetia indica and Orobanche coerulescens, two other herbaceous plants, Arisaema heterophyllum and Glehnia littoralis. Aeginetia indica in particular is considered an important plant in terms of plant distribution, because in Korea it can be found only in Jeju Island, in the crater of Seongsan Ilchulbong Tuff Cone. There are additionally 300 species of marine algae on the Seongsan Ilchulbong Tuff Cone.
Diverse new species were found in this area including Dasyiphonia chejuensis. Duration: It takes one hour to climb to the top and to go down. Opening Hours Summer 07:10-19:00 Winter 07:30-18:00 Parking Facilities Available and free Admission Fees Individuals - Adults 2,000 won / Youth 1,000 won / Children 1,000 won Groups - Adults 1,600 won / Youth 800 won / Children 800 won * Groups: 10 people or more * Adults, Children There is a luggage storage room before the entrance. World Heritage Sites in South Korea Hallasan Gimnyeonggul The Geomunoreum Lava Tube System Manjanggul Jeju Special Self-Governing Provincial Tourism Association "World Heritage sites". Korea Herald. 2010-03-30. "Jeju volcanic island and lava tubes: Invaluable ecological treasure trove". Korea Herald. 2008-09-12. "Jeju sites named UNESCO global geoparks". Korea Herald. 2010-10-04. "A UNESCO Sunrise Seongsan Ilchulbong". The Korea Times. 2008-06-26. "Seongsan Ilchulbong, Jeju's Floating Castle". The Jeju Weekly. 2011-01-16. "Visitors to Seongsan Sunrise Peak up 25% in 2011".
The Jeju Weekly. 2012-01-02. Jeju Volcanic Island and Lava Tubes, UNESCO Jeju Special Self-Governing Provincial Tourism Association Jeju Special Self-Governing Province Jeju World Natural Heritage