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107-653: Elevations range from 6,400 feet (2,000 m) to 8,374 feet (2,552 m). The terrain is a volcanic plateau with 75% covered by water and conifer forests and the remainder being barren rock such as cliff faces, talus slopes and cinder cones. Most of this area has been preserved since 1932 which makes the Caribou Wilderness one of the few remaining pristine forests of the California Cascade region. There are 23 named lakes, innumerable unnamed ponds and tarns, cinder cones and volcanic buttes within

214-418: A forest dynamics perspective, old-growth forest is in a stage that follows understory reinitiation stage. Those stages are: Of importance is that while the stand switches from one tree community to another, the stand will not necessarily go through old-growth stage between those stages. Some tree species have a relatively open canopy. That allows more shade-tolerant tree species to establish below even before

321-478: A ghost town ) and Fourpeaked Mountain in Alaska, which, before its September 2006 eruption, had not erupted since before 8000 BCE. Old-growth forest An old-growth forest (also referred to as primary forest ) is a forest that has developed over a long period of time without disturbance . Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of

428-484: A magma chamber below the surface. The process that forms volcanoes is called volcanism . On Earth, volcanoes are most often found where tectonic plates are diverging or converging , and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas

535-432: A biodiversity that is different from other forest stages. The characteristic topography of much old-growth forest consists of pits and mounds. Mounds are caused by decaying fallen trees, and pits ( tree throws ) by the roots pulled out of the ground when trees fall due to natural causes, including being pushed over by animals. Pits expose humus -poor, mineral-rich soil and often collect moisture and fallen leaves, forming

642-464: A conifer area. Fungal spores blow in on the winds and take up residence at the foot of trees. One type, called the king bolete , is the edible mushroom most sought. Not all fungi have a symbiotic relationship with the trees, some fungi are parasitic, causing heartwood rot. Along some trails in the Caribou, hikers will see a timber-destroying (causes brown rot) pore fungi called the red-belt fomes . It

749-577: A different potential to store carbon. For example, this potential is particularly high in the Pacific Northwest where forests are relatively productive, trees live a long time, decomposition is relatively slow, and fires are infrequent. The differences between forests must, therefore, be taken into consideration when determining how they should be managed to store carbon. A 2019 study projected that old-growth forests in Southeast Asia ,

856-767: A different spatial location relative to the main canopy, hence each one receives a different amount of light. The mixed age of the forest is an important criterion in ensuring that the forest is a relatively stable ecosystem in the long term. A climax stand that is uniformly aged becomes senescent and degrades within a relatively short time to result in a new cycle of forest succession . Thus, uniformly aged stands are less stable ecosystems. Boreal forests are more uniformly aged, as they are normally subject to frequent stand-replacing wildfires. Forest canopy gaps are essential in creating and maintaining mixed-age stands. Also, some herbaceous plants only become established in canopy openings, but persist beneath an understory. Openings are

963-437: A graduated spectrum, with much overlap between categories, and does not always fit neatly into only one of these three separate categories. The USGS defines a volcano as "erupting" whenever the ejection of magma from any point on the volcano is visible, including visible magma still contained within the walls of the summit crater. While there is no international consensus among volcanologists on how to define an active volcano,

1070-563: A healthy fungal ecosystem, and presence of indicator species. Old-growth forests are often biologically diverse , and home to many rare species , threatened species , and endangered species of plants and animals, such as the northern spotted owl , marbled murrelet and fisher , making them ecologically significant. Levels of biodiversity may be higher or lower in old-growth forests compared to that in second-growth forests, depending on specific circumstances, environmental variables, and geographic variables. Logging in old-growth forests

1177-410: A moist, relatively mild climate, some old-growth trees have attained notable height and girth (DBH: diameter at breast height), accompanied by notable biodiversity in terms of the species supported. Therefore, for most people, the physical size of the trees is the most recognized hallmark of old-growth forests, even though the ecologically productive areas that support such large trees often comprise only

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1284-443: A paper was published suggesting a new definition for the word 'volcano' that includes processes such as cryovolcanism . It suggested that a volcano be defined as 'an opening on a planet or moon's surface from which magma , as defined for that body, and/or magmatic gas is erupted.' This article mainly covers volcanoes on Earth. See § Volcanoes on other celestial bodies and cryovolcano for more information. The word volcano

1391-704: A result of industrial logging operations. In 2006, about 61,000 hectares of tall-eucalypt RFA old-growth forests remained unprotected. Recent logging attempts in the Upper Florentine Valley have sparked a series of protests and media attention over the arrests that have taken place in this area. Additionally, Gunns Limited , the primary forestry contractor in Tasmania, has been under recent criticism by political and environmental groups over its practice of woodchipping timber harvested from old-growth forests. Increased understanding of forest dynamics in

1498-550: A result of tree death due to small impact disturbances such as wind, low-intensity fires, and tree diseases. Old-growth forests are unique, usually having multiple horizontal layers of vegetation representing a variety of tree species , age classes, and sizes, as well as "pit and mound" soil shape with well-established fungal nets . As old-growth forest is structurally diverse, it provides higher-diversity habitat than forests in other stages. Thus, sometimes higher biological diversity can be sustained in old-growth forests, or at least

1605-432: A severe disturbance, such as wildfire, insect infestation, or harvesting, is often called second-growth or 'regeneration' until enough time passes for the effects of the disturbance to be no longer evident. Depending on the forest, this may take from a century to several millennia. Hardwood forests of the eastern United States can develop old-growth characteristics in 150–500 years. In British Columbia , Canada, old growth

1712-486: A source of raw materials. These services include making breathable air, making pure water, carbon storage, regeneration of nutrients, maintenance of soils, pest control by insectivorous bats and insects, micro- and macro-climate control, and the storage of a wide variety of genes. The effects of old-growth forests in relation to global warming have been addressed in various studies and journals. The Intergovernmental Panel on Climate Change said in its 2007 report : "In

1819-412: A substrate for seedling trees. Intact soils harbor many life forms that rely on them. Intact soils generally have very well-defined horizons, or soil profiles . Different organisms may need certain well-defined soil horizons to live, while many trees need well-structured soils free of disturbance to thrive. Some herbaceous plants in northern hardwood forests must have thick duff layers (which are part of

1926-400: A thick organic layer that is able to nurture certain types of organisms. Mounds provide a place free of leaf inundation and saturation, where other types of organisms thrive. Standing snags provide food sources and habitat for many types of organisms. In particular, many species of dead-wood predators, such as woodpeckers , must have standing snags available for feeding. In North America,

2033-417: A useful number to measure. So, some forests may be excluded from being categorized as old-growth even if they have old-growth attributes just because they are too young. Also, older forests can lack some old-growth attributes and be categorized as old-growth just because they are so old. The idea of using age is also problematic, because human activities can influence the forest in varied ways. For example, after

2140-584: A very small portion of the total area that has been mapped as old-growth forest. (In high-altitude, harsh climates, trees grow very slowly and thus remain at a small size. Such trees also qualify as old growth in terms of how they are mapped, but are rarely recognized by the general public as such.) The debate over old-growth definitions has been inextricably linked with a complex range of social perceptions about wilderness preservation, biodiversity, aesthetics, and spirituality, as well as economic or industrial values. In logging terms, old-growth stands are past

2247-632: A volcano is largely determined by the composition of the lava it erupts. The viscosity (how fluid the lava is) and the amount of dissolved gas are the most important characteristics of magma, and both are largely determined by the amount of silica in the magma. Magma rich in silica is much more viscous than silica-poor magma, and silica-rich magma also tends to contain more dissolved gases. Lava can be broadly classified into four different compositions: Mafic lava flows show two varieties of surface texture: ʻAʻa (pronounced [ˈʔaʔa] ) and pāhoehoe ( [paːˈho.eˈho.e] ), both Hawaiian words. ʻAʻa

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2354-555: A volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are varied. The structure and behaviour of volcanoes depend on several factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus . Vents that issue volcanic material (including lava and ash ) and gases (mainly steam and magmatic gases) can develop anywhere on

2461-465: A volcano that has experienced one or more eruptions that produced over 1,000 cubic kilometres (240 cu mi) of volcanic deposits in a single explosive event. Such eruptions occur when a very large magma chamber full of gas-rich, silicic magma is emptied in a catastrophic caldera -forming eruption. Ash flow tuffs emplaced by such eruptions are the only volcanic product with volumes rivalling those of flood basalts . Supervolcano eruptions, while

2568-399: A wilderness. There are no man-made structures or conveniences, although occasionally evidence of prior land use before the wilderness designation, such as old fences and tree blazes are found. The Caribou is one of the areas protected by the first major legislation for setting aside lands from development and resource extraction. The 1964 Wilderness Act created the Caribou Wilderness out of what

2675-739: Is a volcanic field of over 60 cinder cones. Based on satellite images, it has been suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and the Moon. Stratovolcanoes (composite volcanoes) are tall conical mountains composed of lava flows and tephra in alternate layers, the strata that gives rise to the name. They are also known as composite volcanoes because they are created from multiple structures during different kinds of eruptions. Classic examples include Mount Fuji in Japan, Mayon Volcano in

2782-414: Is a contentious issue in many parts of the world. Excessive logging reduces biodiversity, affecting not only the old-growth forest itself, but also indigenous species that rely upon old-growth forest habitat. Some forests in the old-growth stage have a mix of tree ages, due to a distinct regeneration pattern for this stage. New trees regenerate at different times from each other, because each of them has

2889-596: Is a white and yellow fungi on the bark of both white fir and red fir trees. An interesting aspect of red-belt fomes is that it has a laquared feel if touched. Before this area became a federally protected wilderness in 1964, it had been previously protected as a primitive area since 1932. When the National Park Service was created in 1916, most of the first National Parks were carved out of National Forest Lands. Beginning in 1929, The United States Forest Service set some areas aside as primitive areas to keep

2996-669: Is affected. Climate change showed an impact on the mortality of some dominant tree species, as observed in the Korean pine . Climate change also showed an effect on the composition of species when forests were surveyed over a 10- and 20-year period, which may disrupt the overall productivity of the forest. According to the World Resources Institute , as of January 2009, only 21% of the original old-growth forests that once existed on Earth are remaining. An estimated one-half of Western Europe's forests were cleared before

3103-412: Is characterized by a rough, clinkery surface and is the typical texture of cooler basalt lava flows. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Pāhoehoe flows are sometimes observed to transition to ʻaʻa flows as they move away from the vent, but never the reverse. More silicic lava flows take the form of block lava, where

3210-615: Is defined as 120 to 140 years of age in the interior of the province where fire is a frequent and natural occurrence. In British Columbia's coastal rainforests , old growth is defined as trees more than 250 years, with some trees reaching more than 1,000 years of age. In Australia, eucalypt trees rarely exceed 350 years of age due to frequent fire disturbance. Forest types have very different development patterns, natural disturbances and appearances. A Douglas-fir stand may grow for centuries without disturbance while an old-growth ponderosa pine forest requires frequent surface fires to reduce

3317-565: Is derived from the name of Vulcano , a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan , the god of fire in Roman mythology . The study of volcanoes is called volcanology , sometimes spelled vulcanology . According to the theory of plate tectonics, Earth's lithosphere , its rigid outer shell, is broken into sixteen larger and several smaller plates. These are in slow motion, due to convection in

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3424-522: Is easy because the landscape has only moderate hills and valleys. No wilderness permits are required, only a California campfire permit for open fires. There are many other trails connecting to other lakes such as Evelyn Lakes as well as trails to the national park's backcountry wilderness area on the west. Backpacking and day hikes are possible with a variety of one-way or loop trips of any length. There are lakes within two miles (3 km) of any trailhead as well as volcanic cinder cones and rocky cliffs for

3531-584: Is expressed using the volcanic explosivity index (VEI), which ranges from 0 for Hawaiian-type eruptions to 8 for supervolcanic eruptions. As of December 2022 , the Smithsonian Institution 's Global Volcanism Program database of volcanic eruptions in the Holocene Epoch (the last 11,700 years) lists 9,901 confirmed eruptions from 859 volcanoes. The database also lists 1,113 uncertain eruptions and 168 discredited eruptions for

3638-433: Is more accurate in forests where the species that constitute old-growth have long lifespans and succession is slow. Common cultural definitions and common denominators regarding what comprises old-growth forest, and the variables that define, constitute and embody old-growth forests include: Additionally, in mountainous, temperate landscapes (such as Western North America), and specifically in areas of high-quality soil and

3745-919: Is not the most commercially viable timber—in British Columbia, Canada, harvesting in the coastal region is moving to younger second-growth stands. A 2001 scientific symposium in Canada found that defining old growth in a scientifically meaningful, yet policy-relevant, manner presents some basic difficulties, especially if a simple, unambiguous, and rigorous scientific definition is sought. Symposium participants identified some attributes of late-successional, temperate-zone, old-growth forest types that could be considered in developing an index of "old-growthness" and for defining old-growth forests: Structural features: Compositional features: Process features: Old-growth forests provide ecosystem services that may be far more important to society than their use as

3852-537: Is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analysed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near

3959-557: Is seen as extremely economically unproductive, as timber can only be collected from falling trees, and also potentially damaging to nearby managed groves by creating environments conducive to root rot. It may be more productive to cut the old growth down and replace the forest with a younger one. The island of Tasmania , just off the southeast coast of Australia, has the largest amount of temperate old-growth rainforest reserves in Australia with around 1,239,000 hectares in total. While

4066-471: Is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland , as well. Lava domes are built by slow eruptions of highly viscous lava. They are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount St. Helens , but can also form independently, as in

4173-617: The Cascade Volcanoes or the Japanese Archipelago , or the eastern islands of Indonesia . Hotspots are volcanic areas thought to be formed by mantle plumes , which are hypothesized to be columns of hot material rising from the core-mantle boundary. As with mid-ocean ridges, the rising mantle rock experiences decompression melting which generates large volumes of magma. Because tectonic plates move across mantle plumes, each volcano becomes inactive as it drifts off

4280-626: The Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere . Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus. Mars has significant volcanoes. In 2009,

4387-486: The Middle Ages , and 90% of the old-growth forests that existed in the contiguous United States in the 1600s have been cleared. The large trees in old-growth forests are economically valuable, and have been subject to aggressive logging throughout the world. This has led to many conflicts between logging companies and environmental groups . From certain forestry perspectives, fully maintaining an old-growth forest

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4494-717: The Regional Forest Agreement (RFA) attempted to prevent the clearfelling of defined "old-growth forests". This led to struggles over what constitutes "old growth". For example, in Western Australia, the timber industry tried to limit the area of old growth in the karri forests of the Southern Forests Region; this led to the creation of the Western Australian Forests Alliance , the splitting of

4601-474: The United Nations defines primary forests as naturally regenerated forests of native tree species where there are no clearly visible indications of human activity and the ecological processes are not significantly disturbed. One-third (34 percent) of the world's forests are primary forests. Old-growth features include diverse tree-related structures that provide diverse wildlife habitats that increases

4708-531: The biodiversity of the forested ecosystem . Virgin or first-growth forests are old-growth forests that have never been logged. The concept of diverse tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters, and diverse tree species and classes and sizes of woody debris. As of 2020 , the world has 1.11  billion   ha (2.7 billion acres) of primary forest remaining. Combined, three countries (Brazil, Canada, and Russia) host more than half (61 percent) of

4815-834: The landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Kīlauea in Hawaii. Volcanic craters are not always at the top of a mountain or hill and may be filled with lakes such as with Lake Taupō in New Zealand. Some volcanoes can be low-relief landform features, with the potential to be hard to recognize as such and be obscured by geological processes. Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter , Saturn , and Neptune ; and mud volcanoes , which are structures often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when

4922-535: The spotted owl is well known for needing standing snags for nesting habitat. Fallen timber, or coarse woody debris , contributes carbon -rich organic matter directly to the soil , providing a substrate for mosses , fungi, and seedlings , and creating microhabitats by creating relief on the forest floor. In some ecosystems such as the temperate rain forest of the North American Pacific coast , fallen timber may become nurse logs , providing

5029-652: The Liberal Government of Western Australia and the election of the Gallop Labor Government. Old-growth forests in this region have now been placed inside national parks . A small proportion of old-growth forests also exist in South-West Australia and are protected by federal laws from logging, which has not occurred there for more than 20 years. In British Columbia , Canada , old-growth forests must be maintained in each of

5136-477: The National Park Service was even in existence. And each new national park had to be approved by the U.S. Congress. Stephen T. Mather, Director of the National Park Service had made his ideas of park expansion at the expense of the national forest system increasingly apparent to the Forest Service. He had generated such support for the park system that there was at least a fair chance of many large areas in

5243-883: The Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift , the Wells Gray-Clearwater volcanic field , and the Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary , 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism , of which

5350-552: The Park Service from continuing to acquire forest lands. At least that is the conclusion of economist David Gerard, who wrote about the competing interests between the two federal agencies: The Park Service under the federal Department of the Interior and the Forest Service, managed by the federal Department of Agriculture . The forest service already managed 151 million acres (610,000 km) of forest reserves before

5457-622: The Philippines, and Mount Vesuvius and Stromboli in Italy. Ash produced by the explosive eruption of stratovolcanoes has historically posed the greatest volcanic hazard to civilizations. The lavas of stratovolcanoes are higher in silica, and therefore much more viscous, than lavas from shield volcanoes. High-silica lavas also tend to contain more dissolved gas. The combination is deadly, promoting explosive eruptions that produce great quantities of ash, as well as pyroclastic surges like

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5564-613: The USGS defines a volcano as active whenever subterranean indicators, such as earthquake swarms , ground inflation, or unusually high levels of carbon dioxide or sulfur dioxide are present. The USGS defines a dormant volcano as any volcano that is not showing any signs of unrest such as earthquake swarms, ground swelling, or excessive noxious gas emissions, but which shows signs that it could yet become active again. Many dormant volcanoes have not erupted for thousands of years, but have still shown signs that they may be likely to erupt again in

5671-446: The atmosphere. Proponents of harvesting the forest argue the carbon stored in wood is available for use as biomass energy (displacing fossil fuel use), although using biomass as a fuel produces air pollution in the form of carbon monoxide , nitrogen oxides , volatile organic compounds , particulates, and other pollutants, in some cases at levels above those from traditional fuel sources such as coal or natural gas. Each forest has

5778-510: The boundary with the Yukon Territory . Mud volcanoes (mud domes) are formations created by geo-excreted liquids and gases, although several processes may cause such activity. The largest structures are 10 kilometres in diameter and reach 700 meters high. The material that is expelled in a volcanic eruption can be classified into three types: The concentrations of different volcanic gases can vary considerably from one volcano to

5885-402: The case of Lassen Peak . Like stratovolcanoes, they can produce violent, explosive eruptions, but the lava generally does not flow far from the originating vent. Cryptodomes are formed when viscous lava is forced upward causing the surface to bulge. The 1980 eruption of Mount St. Helens was an example; lava beneath the surface of the mountain created an upward bulge, which later collapsed down

5992-421: The economic optimum for harvesting—usually between 80 and 150 years, depending on the species. Old-growth forests were often given harvesting priority because they had the most commercially valuable timber, they were considered to be at greater risk of deterioration through root rot or insect infestation, and they occupied land that could be used for more productive second-growth stands. In some regions, old growth

6099-799: The enormous area they cover, and subsequent concealment under vegetation and glacial deposits, supervolcanoes can be difficult to identify in the geologic record without careful geologic mapping . Known examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States); Lake Taupō in New Zealand; Lake Toba in Sumatra , Indonesia; and Ngorongoro Crater in Tanzania. Volcanoes that, though large, are not large enough to be called supervolcanoes, may also form calderas in

6206-431: The flow is covered with angular, vesicle-poor blocks. Rhyolitic flows typically consist largely of obsidian . Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface . These violent explosions produce particles of material that can then fly from

6313-439: The forest service for having ancient forests of white fir, western white pine, sugar pine, lodgepole pine, red fir, incense cedar and Jeffrey pine. This proposed addition did not make it into the 2006 Northern California Coastal Wild Heritage Wilderness Act . Volcanic A volcano is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from

6420-436: The forest will switch back to understory reinitiation stage. Using the stand dynamics definition, old-growth can be easily evaluated using structural attributes. However, in some forest ecosystems, this can lead to decisions regarding the preservation of unique stands or attributes that will disappear over the next few decades because of natural succession processes. Consequently, using stand dynamics to define old-growth forests

6527-489: The forests being transferred to the Park Service. These political maneuverings by the US Forest Service in the years 1929 - 1964 helped in the development of the wilderness preservation system of today. Wilderness areas are managed to preserve the natural, undeveloped conditions as much as possible so there are limitations in the use for recreation. No motorized equipment, vehicles or bicycles can be brought into

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6634-472: The forests is vital to climate change mitigation . Old-growth forests tend to have large trees and standing dead trees, multilayered canopies with gaps that result from the deaths of individual trees, and coarse woody debris on the forest floor. The trees of old-growth forests develop distinctive attributes not seen in younger trees, such as more complex structures and deeply fissured bark that can harbor rare lichens and mosses. A forest regenerated after

6741-447: The forests, destroying the forests in the process, to generate short-term profits, while environmentalists seek to preserve the forests in their pristine state for benefits such as water purification , flood control , weather stability, maintenance of biodiversity, and nutrient cycling . Moreover, old-growth forests are more efficient at sequestering carbon than newly planted forests and fast-growing timber plantations , thus preserving

6848-610: The formation of a submarine volcano off the coast of Mayotte . Subglacial volcanoes develop underneath ice caps . They are made up of lava plateaus capping extensive pillow lavas and palagonite . These volcanoes are also called table mountains, tuyas , or (in Iceland) mobergs. Very good examples of this type of volcano can be seen in Iceland and in British Columbia . The origin of the term comes from Tuya Butte , which

6955-585: The future. In an article justifying the re-classification of Alaska's Mount Edgecumbe volcano from "dormant" to "active", volcanologists at the Alaska Volcano Observatory pointed out that the term "dormant" in reference to volcanoes has been deprecated over the past few decades and that "[t]he term "dormant volcano" is so little used and undefined in modern volcanology that the Encyclopedia of Volcanoes (2000) does not contain it in

7062-466: The glossaries or index", however the USGS still widely employs the term. Previously a volcano was often considered to be extinct if there were no written records of its activity. Such a generalization is inconsistent with observation and deeper study, as has occurred recently with the unexpected eruption of the Chaitén volcano in 2008. Modern volcanic activity monitoring techniques, and improvements in

7169-492: The interior of a continent and lead to rifting. Early stages of rifting are characterized by flood basalts and may progress to the point where a tectonic plate is completely split. A divergent plate boundary then develops between the two halves of the split plate. However, rifting often fails to completely split the continental lithosphere (such as in an aulacogen ), and failed rifts are characterized by volcanoes that erupt unusual alkali lava or carbonatites . Examples include

7276-427: The landscape patterns and habitat conditions normally maintained in nature . This coarse filter approach to biodiversity conservation recognizes ecological processes and provides for a dynamic distribution of old growth across the landscape. And all seral stages—young, medium, and old—support forest biodiversity. Plants and animals rely on different forest ecosystem stages to meet their habitat needs. In Australia ,

7383-525: The late 20th century led the scientific community to identify a need to inventory, understand, manage, and conserve representative examples of old-growth forests with their associated characteristics and values. Literature around old growth and its management is inconclusive about the best way to characterize the true essence of an old-growth stand. A better understanding of natural systems has resulted in new ideas about forest management, such as managed natural disturbances, which should be designed to achieve

7490-620: The local Regional Forest Agreement (RFA) was originally designed to protect much of this natural wealth, many of the RFA old-growth forests protected in Tasmania consist of trees of little use to the timber industry. RFA old-growth and high conservation value forests that contain species highly desirable to the forestry industry have been poorly preserved. Only 22% of Tasmania's original tall-eucalypt forests managed by Forestry Tasmania have been reserved. Ten thousand hectares of tall-eucalypt RFA old-growth forest have been lost since 1996, predominantly as

7597-408: The logging of 30% of the trees, less time is needed for old-growth to come back than after removal of 80% of the trees. Although depending on the species logged, the forest that comes back after a 30% harvest may consist of proportionately fewer hardwood trees than a forest logged at 80% in which the light competition by less important tree species does not inhibit the regrowth of vital hardwoods. From

7704-413: The long term, a sustainable forest management strategy aimed at maintaining or increasing forest carbon stocks, while producing an annual sustained yield of timber, fibre, or energy from the forest, will generate the largest sustained mitigation benefit." Old-growth forests are often perceived to be in equilibrium or in a state of decay. However, evidence from analysis of carbon stored above ground and in

7811-481: The majority of which are in Indonesia and Malaysia , are able to sequester carbon or be a net emitter of greenhouse gases based on deforestation scenarios over the subsequent decades. Old-growth forests have the potential to impact climate change, but climate change is also impacting old-growth forests. As the effects of global warming grow more substantial, the ability of old-growth forests to sequester carbon

7918-419: The mid-oceanic ridge is above sea level, volcanic islands are formed, such as Iceland . Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. The oceanic plate subducts (dives beneath the continental plate), forming a deep ocean trench just offshore. In a process called flux melting , water released from the subducting plate lowers the melting temperature of

8025-551: The modelling of the factors that produce eruptions, have helped the understanding of why volcanoes may remain dormant for a long time, and then become unexpectedly active again. The potential for eruptions, and their style, depend mainly upon the state of the magma storage system under the volcano, the eruption trigger mechanism and its timescale. For example, the Yellowstone volcano has a repose/recharge period of around 700,000 years, and Toba of around 380,000 years. Vesuvius

8132-409: The more adventurous visitors. Off-trail travel is possible but challenging due to many large fallen trees and brush between wet meadows which is the nature of a wilderness area. A wilderness addition was proposed for areas just outside the present boundaries including Indian Meadow (near Hay Meadow) and the lake for which the wilderness is named. These 2,000 acres (8.1 km) have been identified by

8239-415: The most dangerous type, are very rare; four are known from the last million years , and about 60 historical VEI 8 eruptions have been identified in the geologic record over millions of years. A supervolcano can produce devastation on a continental scale, and severely cool global temperatures for many years after the eruption due to the huge volumes of sulfur and ash released into the atmosphere. Because of

8346-438: The mud volcano is actually a vent of an igneous volcano. Volcanic fissure vents are flat, linear fractures through which lava emerges. Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically but are characterized by relatively gentle effusive eruptions . Since low-viscosity magma

8453-452: The next. Water vapour is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide . Other principal volcanic gases include hydrogen sulfide , hydrogen chloride , and hydrogen fluoride . A large number of minor and trace gases are also found in volcanic emissions, for example hydrogen , carbon monoxide , halocarbons , organic compounds, and volatile metal chlorides. The form and style of an eruption of

8560-876: The north side of the mountain. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 metres (100 to 1,300 ft) high. Most cinder cones erupt only once and some may be found in monogenetic volcanic fields that may include other features that form when magma comes into contact with water such as maar explosion craters and tuff rings . Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico , Caja del Rio

8667-625: The northeast at 7,989 ft. Recreational activities include day hiking , backpacking, fishing, horseback riding , cross-country skiing, nature photography and rock climbing . The Forest Service encourages the practice of Leave No Trace principles of outdoor travel to minimize human impact on the environment . The forest is lodgepole pine , Jeffrey pine , ponderosa pine , Douglas fir , white and red fir , western white pine , incense cedar , and hemlock . 21 of Caribou's lakes are stocked by air with rainbow trout . Black-tailed deer and black bears along with squirrels, chipmunks, and

8774-549: The ocean surface as new islands or floating pumice rafts . In May and June 2018, a multitude of seismic signals were detected by earthquake monitoring agencies all over the world. They took the form of unusual humming sounds, and some of the signals detected in November of that year had a duration of up to 20 minutes. An oceanographic research campaign in May 2019 showed that the previously mysterious humming noises were caused by

8881-420: The ocean surface, due to the rapid cooling effect and increased buoyancy in water (as compared to air), which often causes volcanic vents to form steep pillars on the ocean floor. Hydrothermal vents are common near these volcanoes, and some support peculiar ecosystems based on chemotrophs feeding on dissolved minerals. Over time, the formations created by submarine volcanoes may become so large that they break

8988-471: The ocean's surface. In the deep ocean basins, the tremendous weight of the water prevents the explosive release of steam and gases; however, submarine eruptions can be detected by hydrophones and by the discoloration of water because of volcanic gases . Pillow lava is a common eruptive product of submarine volcanoes and is characterized by thick sequences of discontinuous pillow-shaped masses which form underwater. Even large submarine eruptions may not disturb

9095-468: The one that destroyed the city of Saint-Pierre in Martinique in 1902. They are also steeper than shield volcanoes, with slopes of 30–35° compared to slopes of generally 5–10°, and their loose tephra are material for dangerous lahars . Large pieces of tephra are called volcanic bombs . Big bombs can measure more than 1.2 metres (4 ft) across and weigh several tons. A supervolcano is defined as

9202-425: The overlying mantle wedge, thus creating magma . This magma tends to be extremely viscous because of its high silica content, so it often does not reach the surface but cools and solidifies at depth . When it does reach the surface, however, a volcano is formed. Thus subduction zones are bordered by chains of volcanoes called volcanic arcs . Typical examples are the volcanoes in the Pacific Ring of Fire , such as

9309-619: The plume, and new volcanoes are created where the plate advances over the plume. The Hawaiian Islands are thought to have been formed in such a manner, as has the Snake River Plain , with the Yellowstone Caldera being part of the North American plate currently above the Yellowstone hotspot . However, the mantle plume hypothesis has been questioned. Sustained upwelling of hot mantle rock can develop under

9416-402: The protected (from hunting) pine marten live here. There are bald eagles and ospreys overhead, mergansers and grebes on the ponds and lakes. Much smaller in size, but critically important to the forest ecosystem are the fungi . The cup fungus , for instance, can be found in the Caribou. As the sanitary agents of the forest that consume dead organic matter, fungi spread on the floor of

9523-524: The province's ecological units to meet biodiversity needs. In the United States , from 2001, around a quarter of the federal forests are protected from logging. In December 2023, Biden's administration introduced a rule, according to which, logging is strongly limited in old growth forests, but permitted in "mature forests", representing a compromise between the logging industry and environmental activists. In 2006, Greenpeace identified that

9630-435: The same time interval. Volcanoes vary greatly in their level of activity, with individual volcanic systems having an eruption recurrence ranging from several times a year to once in tens of thousands of years. Volcanoes are informally described as erupting , active , dormant , or extinct , but the definitions of these terms are not entirely uniform among volcanologists. The level of activity of most volcanoes falls upon

9737-492: The same way; they are often described as "caldera volcanoes". Submarine volcanoes are common features of the ocean floor. Volcanic activity during the Holocene Epoch has been documented at only 119 submarine volcanoes, but there may be more than one million geologically young submarine volcanoes on the ocean floor. In shallow water, active volcanoes disclose their presence by blasting steam and rocky debris high above

9844-607: The shade-tolerant species and regenerate the canopy species. In the boreal forest of Canada , catastrophic disturbances like wildfires minimize opportunities for major accumulations of dead and downed woody material and other structural legacies associated with old growth conditions. Typical characteristics of old-growth forest include the presence of older trees, minimal signs of human disturbance, mixed-age stands, presence of canopy openings due to tree falls, pit-and-mound topography , down wood in various stages of decay, standing snags (dead trees), multilayered canopies, intact soils ,

9951-462: The soil has shown old-growth forests are more productive at storing carbon than younger forests. Forest harvesting has little or no effect on the amount of carbon stored in the soil, but other research suggests older forests that have trees of many ages, multiple layers, and little disturbance have the highest capacities for carbon storage. As trees grow, they remove carbon from the atmosphere, and protecting these pools of carbon prevents emissions into

10058-516: The soil profile). Fungal ecosystems are essential for efficient in-situ recycling of nutrients back into the entire ecosystem. Stand age can also be used to categorize a forest as old-growth. For any given geographical area, the average time since disturbance until a forest reaches the old growth stage can be determined. This method is useful, because it allows quick and objective determination of forest stage. However, this definition does not provide an explanation of forest function. It just gives

10165-622: The solidified erupted material that makes up the mantle of a volcano may be stripped away that its inner anatomy becomes apparent. Using the metaphor of biological anatomy , such a process is called "dissection". Cinder Hill , a feature of Mount Bird on Ross Island , Antarctica , is a prominent example of a dissected volcano. Volcanoes that were, on a geological timescale, recently active, such as for example Mount Kaimon in southern Kyūshū , Japan , tend to be undissected. Eruption styles are broadly divided into magmatic, phreatomagmatic, and phreatic eruptions. The intensity of explosive volcanism

10272-406: The surrounding areas, and initially not seismically monitored before its unanticipated and catastrophic eruption of 1991. Two other examples of volcanoes that were once thought to be extinct, before springing back into eruptive activity were the long-dormant Soufrière Hills volcano on the island of Montserrat , thought to be extinct until activity resumed in 1995 (turning its capital Plymouth into

10379-434: The theory of plate tectonics. For example, some volcanoes are polygenetic with more than one period of activity during their history; other volcanoes that become extinct after erupting exactly once are monogenetic (meaning "one life") and such volcanoes are often grouped together in a geographical region. At the mid-ocean ridges , two tectonic plates diverge from one another as hot mantle rock creeps upwards beneath

10486-444: The thinned oceanic crust . The decrease of pressure in the rising mantle rock leads to adiabatic expansion and the partial melting of the rock, causing volcanism and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans, and so most volcanic activity on Earth is submarine, forming new seafloor . Black smokers (also known as deep sea vents) are evidence of this kind of volcanic activity. Where

10593-431: The underlying ductile mantle , and most volcanic activity on Earth takes place along plate boundaries, where plates are converging (and lithosphere is being destroyed) or are diverging (and new lithosphere is being created). During the development of geological theory, certain concepts that allowed the grouping of volcanoes in time, place, structure and composition have developed that ultimately have had to be explained in

10700-549: The understory reinitiation stage. The shade-tolerant trees eventually outcompete the main canopy trees in stem-exclusion stage. Therefore, the dominant tree species will change, but the forest will still be in stem-exclusion stage until the shade-tolerant species reach old-growth stage. Tree species succession may change tree species' composition once the old-growth stage has been achieved. For example, an old boreal forest may contain some large aspen trees, which may die and be replaced by smaller balsam fir or black spruce. Consequently,

10807-492: The volcano. Solid particles smaller than 2 mm in diameter ( sand-sized or smaller) are called volcanic ash. Tephra and other volcaniclastics (shattered volcanic material) make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geologic record. The production of large volumes of tephra is characteristic of explosive volcanism. Through natural processes, mainly erosion , so much of

10914-424: The volcanoes of the East African Rift . A volcano needs a reservoir of molten magma (e.g. a magma chamber), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice , typically a volcanic cone or mountain. The most common perception of

11021-526: The wilderness. Although there are no year round surface streams, the area provides high quality water for the headwaters of the Susan River , and Bailey Creek, a tributary of the Feather River . The high point is Red Cinder (8,363 ft) located near the boundary between the wilderness and the park. Other peaks are North Caribou (7,785 ft), South Caribou ( 7,753 ft) and Black Butte in

11128-432: The world's primary forest. The area of primary forest has decreased by 81 million ha (200 million acres) since 1990, but the rate of loss more than halved in 2010–2020 compared with the previous decade. Old-growth forests are valuable for economic reasons and for the ecosystem services they provide. This can be a point of contention when some in the logging industry desire to harvest valuable timber from

11235-413: The world's remaining intact forest landscapes are distributed among the continents as follows: [REDACTED]  This article incorporates text from a free content work. Licensed under CC BY-SA 3.0 ( license statement/permission ). Text taken from Global Forest Resources Assessment 2020 Key findings​ , FAO, FAO. [REDACTED]  This article incorporates text from

11342-421: Was a primitive area since 1932. As a result, an almost pristine, old-growth forest describes the Caribou. Three trailheads give access to the wilderness; Hay Meadows in the south, Cone Lake in the north and Silver Lake on the east which is also the most popular entry point; as well, the wilderness can be accessed by trails leading in from Lassen Volcanic National Park to the west. Travel by foot or horseback

11449-421: Was described by Roman writers as having been covered with gardens and vineyards before its unexpected eruption of 79 CE , which destroyed the towns of Herculaneum and Pompeii . Accordingly, it can sometimes be difficult to distinguish between an extinct volcano and a dormant (inactive) one. Long volcano dormancy is known to decrease awareness. Pinatubo was an inconspicuous volcano, unknown to most people in

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