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Thermokarst
Thermokarst is a type of terrain characterised by very irregular surfaces of marshy hollows and small hummocks formed as ice-rich permafrost thaws. The land surface type occurs in Arctic areas, and on a smaller scale in mountainous areas such as the Himalayas and the Swiss Alps. These pitted surfaces resemble clusters of small lakes formed by dissolution of limestone in some karst areas, which is how they came to have "''karst''" attached to their name, even though no limestone is actually present. Small domes that form on the surface due to frost heaving with the onset of winter are only temporary features. They collapse during the following summer thaw, leaving a small surface depression. Some ice lenses grow and form larger surface hummocks ("pingos") which can last for many years, and sometimes become covered with grasses and sedges, until they begin to thaw. These domed surfaces eventually collapse – either annually or after longer periods – and form depressions which bec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retrogressive Thaw Slumps
Retrogressive thaw slumps (RTS), are a type of landslide that occur in the terrestrial Arctic's permafrost region of the circumpolar Northern Hemisphere when an ice-rich section thaws. RTSs develop quickly and can extend across several hectares modifying Arctic coastlines and permafrost terrain. They are the most active and dynamic feature of thermokarstthe collapse of the land surface as ground ice melts. They are thermokarst slope failures due to abrupt thawing of ice-rich permafrost or glaciated terrains. These horseshoe-shaped landslides contribute to the thawing of hectares of permafrost annually and are considered to be one of the most active and dynamic features of thermokarstthe "processes and landforms that involve collapse of the land surface as a result of the melting of ground ice." They are found in permafrost or glaciated regions of the Northern Hemispherethe Tibetan Plateau, Siberia, from the Himalayas to northern Greenland, and in northern Canada's Northwest Territo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retrogressive Thaw Slumps
Retrogressive thaw slumps (RTS), are a type of landslide that occur in the terrestrial Arctic's permafrost region of the circumpolar Northern Hemisphere when an ice-rich section thaws. RTSs develop quickly and can extend across several hectares modifying Arctic coastlines and permafrost terrain. They are the most active and dynamic feature of thermokarstthe collapse of the land surface as ground ice melts. They are thermokarst slope failures due to abrupt thawing of ice-rich permafrost or glaciated terrains. These horseshoe-shaped landslides contribute to the thawing of hectares of permafrost annually and are considered to be one of the most active and dynamic features of thermokarstthe "processes and landforms that involve collapse of the land surface as a result of the melting of ground ice." They are found in permafrost or glaciated regions of the Northern Hemispherethe Tibetan Plateau, Siberia, from the Himalayas to northern Greenland, and in northern Canada's Northwest Territo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permafrost Thaw Ponds In Hudson Bay Canada Near Greenland
Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface is underlain by permafrost, with the total area of around 18 million km2. This includes substantial areas of Alaska, Greenland, Canada and Siberia. It can also be located on mountaintops in the Southern Hemisphere and beneath ice-free areas in the Antarctic. Permafrost does not have to be the first layer that is on the ground. It can be from an inch to several miles deep under the Earth's surface. It frequently occurs in ground ice, but it can also be present in non-porous bedrock. Permafrost is formed from ice holding various types of soil, sand, and rock in combination. Permafrost contains large amounts of biomass and decomposed biomass that has been stored as methane and carbon dioxide, making tundra soil a carbon sink. As global war ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Talik
A talik is a layer of year-round unfrozen ground that lies in permafrost areas. In regions of continuous permafrost, taliks often occur underneath shallow thermokarst lakes and rivers, where the deep water does not freeze in winter and thus the soil underneath does not freeze either. Sometimes closed, open, and through taliks are distinguished. These terms refer to whether the talik is surrounded by permafrost, open at the top (e.g. a thermokarst lake), or open both at the top and above an unfrozen layer beneath the permafrost. Supra-permafrost taliks Due to climate fluctuation or change, some permafrost regions may develop an unfrozen layer between the seasonally thawing and freezing top layer and the permafrost. The layer is called a supra-permafrost ("above the permafrost") talik; it is different from traditional taliks, which are usually associated with water bodies, in that a supra-permafrost talik occurs because the ground that thawed in the summer does not completely refre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pingo
Pingos are intrapermafrost ice-cored hills, high and in diameter. They are typically conical in shape and grow and persist only in permafrost environments, such as the Arctic and subarctic. A pingo is a periglacial landform, which is defined as a non-glacial landform or process linked to colder climates. It is estimated that there are more than 11,000 pingos on Earth. The Tuktoyaktuk peninsula area has the greatest concentration of pingos in the world with a total of 1,350 pingos. There is currently remarkably limited data on pingos. History In 1825, John Franklin made the earliest description of a pingo when he climbed a small pingo on Ellice Island in the Mackenzie Delta. However, it was in 1938 that the term ''pingo'' was first borrowed from the Inuvialuit by the Arctic botanist Alf Erling Porsild in his paper on Earth mounds of the western Arctic coast of Canada and Alaska. Porsild Pingo in Tuktoyaktuk is named in his honour. The term pingos, which in Inuvialuktun m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permafrost
Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface is underlain by permafrost, with the total area of around 18 million km2. This includes substantial areas of Alaska, Greenland, Canada and Siberia. It can also be located on mountaintops in the Southern Hemisphere and beneath ice-free areas in the Antarctic. Permafrost does not have to be the first layer that is on the ground. It can be from an inch to several miles deep under the Earth's surface. It frequently occurs in ground ice, but it can also be present in non-porous bedrock. Permafrost is formed from ice holding various types of soil, sand, and rock in combination. Permafrost contains large amounts of biomass and decomposed biomass that has been stored as methane and carbon dioxide, making tundra soil a carbon sink. As global war ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Batagaika Crater
The Batagaika crater is a thermokarst depression in the Chersky Range area. The biggest permafrost crater in the world, it administratively belongs to the Sakha Republic, Russia, and is in its Verkhoyansky District. Description The depression is in the form of a one-kilometre-long gash up to 100 metres (328 feet) deep, and growing, in the East Siberian taiga, located southeast of Batagay and northeast of the settlement Ese-Khayya, about north-northeast of the capital Yakutsk. The structure is named after the near-flowing Batagayka, a right tributary of the river Yana. The land began to sink due to the thawing permafrost in the 1960s after the surrounding forest was cleared. Flooding also contributed to the enlargement of the crater. Paleontologists have found Ice Age fossils buried in the mud around the rim of the crater. The rim is extremely unstable as there are regular landslides into the crater and the permafrost is constantly thawing. The crater is currently growing in si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Himalayas
The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 100 peaks exceeding in elevation lie in the Himalayas. By contrast, the highest peak outside Asia (Aconcagua, in the Andes) is tall. The Himalayas abut or cross five countries: Bhutan, India, Nepal, China, and Pakistan. The sovereignty of the range in the Kashmir region is disputed among India, Pakistan, and China. The Himalayan range is bordered on the northwest by the Karakoram and Hindu Kush ranges, on the north by the Tibetan Plateau, and on the south by the Indo-Gangetic Plain. Some of the world's major rivers, the Indus, the Ganges, and the Tsangpo–Brahmaputra, rise in the vicinity of the Himalayas, and their combined drainage basin is home to some 600 million people; 53 million people live in the Himalayas. The Himalayas have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swiss Alps
The Alpine region of Switzerland, conventionally referred to as the Swiss Alps (german: Schweizer Alpen, french: Alpes suisses, it, Alpi svizzere, rm, Alps svizras), represents a major natural feature of the country and is, along with the Swiss Plateau and the Swiss portion of the Jura Mountains, one of its three main physiographic regions. The Swiss Alps extend over both the Western Alps and the Eastern Alps, encompassing an area sometimes called Central Alps. While the northern ranges from the Bernese Alps to the Appenzell Alps are entirely in Switzerland, the southern ranges from the Mont Blanc massif to the Bernina massif are shared with other countries such as France, Italy, Austria and Liechtenstein. The Swiss Alps comprise almost all the highest mountains of the Alps, such as Dufourspitze (4,634 m), the Dom (4,545 m), the Liskamm (4,527 m), the Weisshorn (4,506 m) and the Matterhorn (4,478 m). The other following major summits can be found in this list of mountains of S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karst
Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant rocks, such as quartzite, given the right conditions. Subterranean drainage may limit surface water, with few to no rivers or lakes. However, in regions where the dissolved bedrock is covered (perhaps by debris) or confined by one or more superimposed non-soluble rock strata, distinctive karst features may occur only at subsurface levels and can be totally missing above ground. The study of ''paleokarst'' (buried karst in the stratigraphic column) is important in petroleum geology because as much as 50% of the world's hydrocarbon reserves are hosted in carbonate rock, and much of this is found in porous karst systems. Etymology The English word ''karst'' was borrowed from German in the late 19th century, which entered German much earlier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frost Heaving
Frost heaving (or a frost heave) is an upwards swelling of soil during freezing conditions caused by an increasing presence of ice as it grows towards the surface, upwards from the depth in the soil where freezing temperatures have penetrated into the soil (the freezing front or freezing boundary). Ice growth requires a water supply that delivers water to the freezing front via capillary action in certain soils. The weight of overlying soil restrains vertical growth of the ice and can promote the formation of lens-shaped areas of ice within the soil. Yet the force of one or more growing ice lenses is sufficient to lift a layer of soil, as much as or more. The soil through which water passes to feed the formation of ice lenses must be sufficiently porous to allow capillary action, yet not so porous as to break capillary continuity. Such soil is referred to as "frost susceptible". The growth of ice lenses continually consumes the rising water at the freezing front. Differential fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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