Their research on firn aquifers in Southeast Greenland, published in Frontiers in Earth Science, shows that the water in the firn aquifer they studied did eventually reach the ocean.
|
|
The snow and firn must be warmed to freezing before melt can start.
|
|
Winds make the firn vibrate, creating a flute-like effect across the dunes.
|
|
The layer, called the firn, isn't perfectly smooth, but covered in undulations and hills like sand dunes.
|
|
The firn layer in the ice sheet, the boundary between snow and ice, is heating up and becoming denser.
|
|
The recently published paper marks the first time scientists have examined what happens to water entrapped in firn aquifers.
|
|
After years of snowfall, when it gets to about 160 feet, the firn fuses and becomes a block of ice.
|
|
The deepest layers, which were laid down long before recorded history, are under enormous pressure, and the firn is compressed into ice.
|
|
The refrozen snow and firn, bare ice, and meltwater ponds are much darker and absorb more sunlight than fresh snow, promoting even more melt.
|
|
At the top of the sheet there's airy snow, known as firn, that fell last year and the year before and the year before that.
|
|
Journalist Mike Firn in Tokyo told CNN he felt the trembles in a building some 900 kilometers, or more than 550 miles away from the epicenter.
|
|
"The firn layer was buzzing with seemingly constant, pulsating vibration," Douglas MacAyeal, a glaciologist at the University of Chicago, wrote in a commentary about Chaput's findings.
|
|
Bentley would drill a hole deep enough to reach the compact layer of snow known as firn or, better yet, solid ice; place in it an explosive charge; and then register the shock wave using geophones.
|
|
These are called "firn aquifers," and occur when surface-level glacier ice melts in the summer, then keeps its liquid state year-round—thanks to snow that creates a blanket on top of it, trapping it beneath the surface, Poinar said.
|
|
While these reservoirs also exist outside of Greenland—in the Arctic and in mountain glaciers around the world—Poinar described Greenland as "more of a wildcard" in terms of how its melting ice could ultimately contribute to sea level rise, so understanding these firn aquifers is very important.
|
|
Not all meltwater goes into the ocean; the firn has pores, like a sponge, that allows some of the meltwater to refreeze and acts as a buffer to sea level rise, but increasing surface melt is filling the pores, which will lead to more meltwater runoff into the ocean.
|
|
Left to right: West Northwall Firn, East Northwall Firn, Meren Glacier, and Carstensz Glacier. The Meren Glacier disappeared before the West Northwall Firn did. See also animation. Sometime between 1936 and 1962, a single Northwall Firn split into several separate glaciers, the largest being the West Northwall Firn and the East Northwall Firn. Research presented in 2004 of IKONOS satellite imagery of the New Guinean glaciers indicated that in the two years from 2000 to 2002, the West Northwall Firn had lost a further 19.4% of its surface area.
|
|
Where the crystals touch they bond together, squeezing the air between them to the surface or into bubbles. In the summer months, the crystal metamorphosis can occur more rapidly because of water percolation between the crystals. By summer's end, the result is firn. The minimum altitude that firn accumulates on a glacier is called the firn limit, firn line or snowline.
|
|
Puncak Jaya glaciers in 1972. Left to right: West Northwall Firn, East Northwall Firn, Meren Glacier, and Carstensz Glacier. The first and third have now disappeared. See also animation.
|
|
Indeed, in or before 2017, the West Northwall Firn had completely disappeared and the eastern Firn had broken up in three small patches . The East Northwall Firn glaciers are remnants of an icecap that in 1850 measured about and had developed approximately 5,000 years ago. At least one previous icecap also existed in the region between 15,000 and 7,000 years ago.
|
|
Puncak Jaya glaciers in 1972. Left to right: West Northwall Firn, East Northwall Firn, Meren Glacier (now disappeared), and Carstensz Glacier. See also animation. The remaining remnant glaciers on Punkak Jaya were once part of an icecap that developed approximately 5,000 years ago.
|
|
In the cirques the snow firn, which forms specific natural habitat, melts in mid-June.
|
|
The department manages the Florida Information Resource Network (FIRN), which provides Internet access to public schools.
|
|
Sampling the surface of a glacier. There is increasingly dense firn between surface snow and blue glacier ice. Firn field on the top of Säuleck, Hohe Tauern Firn (; from Swiss German "last year's", cognate with before) is partially compacted névé, a type of snow that has been left over from past seasons and has been recrystallized into a substance denser than névé. It is ice that is at an intermediate stage between snow and glacial ice.
|
|
Sometime between 1936 and 1962, a single Northwall Firn split into several separate glaciers, the largest being the East Northwall Firn and the West Northwall Firn. Research presented in 2004 of IKONOS satellite imagery of the New Guinean glaciers indicated that in the two years from 2000 to 2002, the East Northwall Firn had lost a further 4.5% of its surface area. An expedition to the remaining glaciers on Puncak Jaya in 2010 discovered that the ice on the glaciers there is about thick and thinning at a rate of annually. At that rate, the remaining glaciers in the immediate region near Puncak Jaya were expected to last only to the year 2015.
|
|
Firn including penitentes occurs on the mountain at elevations of over and is visible over large distances but there are no presently active, moving glaciers unless they are buried beneath a snow cover. Some sources consider Sillajhuay's firn a glacier however, in which case it would be considered to be the southernmost glacier north of the Arid Diagonal of the Andes. Between 1989 and 2011 the firn lost over half of its surface, interrupted by some small advances, and further retreat is likely. Ice loss between 2000 and 2003 amounted to about .
|
|
Drills may be designed with more than one anti-torque system in order to take advantage of the different performance of the different designs in different kinds of snow and ice. For example, a drill may have skates to be used in hard firn or ice, but also have a leaf-spring system, which will be more effective in soft firn.
|
|
If the fluid is only used in the lower part of the hole, permeability is not an issue. Alternatively the hole can be cased down past the point where the firn turns to ice. If water is used as a drilling fluid, in cold enough temperatures, it will turn to ice in the surrounding snow and firn and seal the hole.Talalay (2014), pp. 341–342.
|
|
Névé in a valley of Haute-Savoie, France Névé is a young, granular type of snow which has been partially melted, refrozen and compacted, yet precedes the form of ice. This type of snow is associated with glacier formation through the process of nivation. Névé that survives a full season of ablation turns into firn, which is both older and slightly denser. Firn eventually becomes glacial ice – the long-lived, compacted ice that glaciers are composed of.
|
|
The definition of Glaciovolcanism is “the interactions of magma with ice in all its forms, including snow, firn and any meltwater.”Smellie, 2000. Subglacial eruptions. In: Sigurdsson, H. (ed.) Encyclopaedia of Volcanoes.
|
|
That research between 1973 and 1976 showed glacier retreat for the Meren Glacier of while the Carstensz Glacier lost . The Northwall Firn, the largest remnant of the icecap that once was atop Puncak Jaya, has itself split into two separate glaciers after 1942. IKONOS satellite imagery of the New Guinean glaciers indicated that by 2002 only glacial area remained, that in the two years from 2000 to 2002, the East Northwall Firn had lost 4.5%, the West Northwall Firn 19.4% and the Carstensz 6.8% of their glacial mass, and that sometime between 1994 and 2000, the Meren Glacier had disappeared altogether. An expedition to the remaining glaciers on Puncak Jaya in 2010 discovered that the ice on the glaciers there is about thick and thinning at a rate of annually.
|
|
The outside barrel of the Prairie Dog is the same as the diameter of the PICO auger, and since the Prairie Dog's anti-torque blades do not perform well in soft snow and firn, it is common to start a hole with the PICO auger and then continue it with the Prairie Dog once dense firn is reached.Bentley et al. (2009), pp. 258–259. The Prairie Dog is relatively heavy, and can require two drillers to handle it as it is being removed from the hole.
|
|
Ecology and Evolution is a biweekly open-access scientific journal covering all areas of ecology, evolution, and conservation. The Editors in Chief of this journal are Allen Moore, Andrew Beckerman, Jenn Firn, Chris Foote, and Gareth Jenkins.
|
|
The depth at which borehole closure prevents dry drilling is strongly dependent on the temperature of the ice; in a temperate glacier, the maximum depth might be , but in a very cold environment such as parts of East Antarctica, dry drilling to might be possible.Bentley et al. (2009), p. 223. Snow and firn are permeable to air, water, and drilling fluids, so any drilling method that requires liquid or compressed air in the hole needs to prevent them from escaping into the surface layers of snow and firn.
|
|
The size of a crystal is related to its growth rate, which in turn depends on the temperature, so the properties of the bubbles can be combined with information on accumulation rates and firn density to calculate the temperature when the firn formed., p. 1098. Radiocarbon dating can be used on the carbon in trapped . In the polar ice sheets there is about 15–20 µg of carbon in the form of in each kilogram of ice, and there may also be carbonate particles from wind-blown dust (loess).
|
|
When drilling deep holes, which require drilling fluid, the hole must be cased (fitted with a cylindrical lining), since otherwise the drilling fluid will be absorbed by the snow and firn. The casing has to reach down to the impermeable ice layers. To install casing a shallow auger can be used to create a pilot hole, which is then reamed (expanded) until it is wide enough to accept the casing; a large diameter auger can also be used, avoiding the need for reaming. An alternative to casing is to use water in the borehole to saturate the porous snow and firn; the water eventually turns to ice.
|
|
Another core at Dye 3 was drilled in 1978 using a Shallow (US) drill type, 10.2 cm diameter, to 90 m. Measurements of [SO42−] and [NO3−] in firn samples spanning the period 1895–1978 were taken from the Dye 3 1978 core down to 70 m.
|
|
Sampling the surface of alt=A scientist in a pit of snow An ice core is a vertical column through a glacier, sampling the layers that formed through an annual cycle of snowfall and melt. As snow accumulates, each layer presses on lower layers, making them denser until they turn into firn. Firn is not dense enough to prevent air from escaping; but at a density of about 830 kg/m3 it turns to ice, and the air within is sealed into bubbles that capture the composition of the atmosphere at the time the ice formed. The depth at which this occurs varies with location, but in Greenland and the Antarctic it ranges from 64 m to 115 m.
|
|
Tetrahydrocannabinol (THC) is one of at least 113 cannabinoids identified in cannabis. THC is the principal psychoactive constituent of cannabis. With chemical name (−)-trans-Δ⁹-tetrahydrocannabinol, the term THC also refers to cannabinoid isomers. Like most pharmacologically active secondary metabolites of plants, THC is a lipid found in cannabis,Firn, Richard (2010).
|
|
The foundation stone was laid in 1870 by the Bishop of Peterborough. The church was the gift of William Perry-Herrick and built to the designs of the architect Ewan Christian. The contractor for the foundations was Firn of Leicester, Osbourne of Leicester constructed the building. The clerk of works was James Nichols.
|
|
Nival is a synonym for snowy. A serac is a group or column of ice intersecting crevasses on a glacier. Firn is a type of snow that has been left over from past seasons and has been recrystallized into a substance denser than névé. It is at an intermediate stage between snow and glacial ice.
|
|
The snowfall provides insulation and the temperatures below maintain a stable 0 C (32 °F). Ice worms can still find plenty of algae in the firn layer, the layer of packed snow in transition to ice. Scientists know little about the ice worm during the winter as the inaccessibility of glaciers prevents further study.
|
|
Dr.Isaksson graduated in geoscience at Umeå University in 1986. She went on to gain an Fil. Lic. from Stockholm University and an M.Sc. from the University of Maine in 1991. With a thesis on Climate records from shallow firn cores, Dronning Maud Land, Antarctica, she was awarded a Ph.D. from Stockholm University in 1994.
|
|
A glacier originates at a location called its glacier head and terminates at its glacier foot, snout, or terminus. Glaciers are broken into zones based on surface snowpack and melt conditions.Benson, C.S., 1961, "Stratigraphic studies in the snow and firn of the Greenland Ice Sheet", Res. Rep. 70, U.S. Army Snow, Ice and Permafrost Res Establ.
|
|
Topography of the glacier's surroundings. There are only a small number of glaciers in the Genaldon River's basin, the largest being Maili at approximately in area. The Kolka Glacier, located next to Maili, is a cirque / valley glacier, with some hanging parts. Kolka is fed by avalanches and collapses of firn and ice all year round.
|
|
The Grabspitze (, ), formerly also called the Hochferner, is the second highest peak in the Pfunderer Mountains after the Wilde Kreuzspitze (3,135 m). The Pfunderer are a subrange of the Zillertal Alps located in the Italian province of South Tyrol. Its former name, "Hochferner", was derived from a firn field that lay to the side of the summit.
|
|
Dirt cones near the Kårsa glacier in Kårsavagge, Sweden A dirt cone is a type of depositional glacial feature. Dirt cones are not actually made entirely of dirt. They have a core of ice, snow, or firn that gets covered with material and insulated. The material, if it is thick enough, will protect the underlying core from ablation.
|
|
Puncak Jaya icecap 1936 Puncak Jaya icecap 1972 While Puncak Jaya's peak is free of ice, there are several glaciers on its slopes, including the Carstensz Glacier, West Northwall Firn, East Northwall Firn and the recently vanished Meren Glacier in the Meren Valley (meren is Dutch for "lakes"). Being equatorial, there is little variation in the mean temperature during the year (around ) and the glaciers fluctuate on a seasonal basis only slightly. However, analysis of the extent of these rare equatorial glaciers from historical records show significant retreat since the 1850s, around the time of the Little Ice Age Maximum which primarily affected the Northern Hemisphere, indicating a regional warming of around per century between 1850 and 1972. The glacier on Puncak Trikora in the Maoke Mountains disappeared completely some time between 1939 and 1962.
|
|
An expedition to the remaining glaciers on Puncak Jaya in 2010 found that the glacial ice was about thick and thinning at a rate of annually. At that rate, the remaining glaciers in the immediate region near Puncak Jaya were expected to last only to the year 2015. Indeed, in or before 2017, the West Northwall Firn had completely disappeared.
|
|
Mount Shirouma is the 26th-tallest mountain in Japan. At , it is the highest peak in the Hakuba section of the Hida Mountains, and one of the top "to climb" peaks for Japanese hikers. It is also one of the few peaks in Japan with year-round snow fields (Firn), in the . It is located within the Chūbu-Sangaku National Park.
|
|
Boreholes drilled with hot water are rather irregular, which makes them unsuitable for certain kinds of investigations, such as speed of borehole closure, or inclinometry measurements. The warm water from the nozzle will continue to melt the borehole walls as it rises, and this will tend to make the hole cone-shaped—if the hole is being drilled at a location with no surface snow or firn, such as an ablation zone in a glacier, then this effect will persist to the top of the borehole. The water supply for a hot water drill can come from water at the surface, if available, or melted snow. The meltwater in the borehole can be reused, but this can only be done once the hole penetrates below the firn to the impermeable ice layer, because above this level the meltwater escapes.
|
|
Anton Colijn, Jean Jacques Dozy and Frits Wissel reached the summit on 5 December 1936 during the Carstensz Expedition over the Northwall Firn. Subsequent ascendants were Heinrich Harrer and company in 1962 and a Japanese-Indonesian expedition in 1964.. Dick Isherwood first ascended the high north face in a solo effort in September 1972.R.J. Isherwood, The Dugundugoo, The Alpine Journal 1973, pp 188–194.
|
|
The West Northwall Firn was a glacial body on Mount Carstensz in the Sudirman Range on the island of New Guinea in Papua province, Indonesia. The glacier was situated at an elevation of approximately to , centered a little over northwest of Ngga Pulu and of Puncak Jaya (Carstensz Pyramid), the highest peak of Oceania. Puncak Jaya region icecap in 1936.Puncak Jaya glaciers in 1972.
|
|
Kathryn Hansen, Glaciers in the Tropics, but Not for Long, at NASA Earth Observatory, February 13, 2018 The West Northwall Firn was a remnant glacier of an icecap that in 1850 measured about and had developed approximately 5,000 years ago. At least one previous icecap also existed in the region between 15,000 and 7,000 years ago, when it also apparently melted away and disappeared.
|
|
Material falls down and protects the sides. The more material is added to the top, the more insulated the core becomes. Over time, it becomes a cone with a layer of material on the outside and a core of ice, snow, or firn on the inside. The material at the top of the cone is generally thicker than the material on the sides of the dirt cone.
|
|
Lúthien and Beren dwelt together in Ossiriand until after the sack of Menegroth. Their abode was known as Dor Firn-i-Guinar: the "Land of the Dead that Lived". They had a son, Dior, called Eluchíl — the heir of Thingol. Years later, Thingol received the Nauglamír from Húrin, who had recovered it from the ruins of Nargothrond after the departure of Glaurung the dragon.
|
|
For an intermediate drilling c. 390 m, the drill was installed 25 m below the surface at the bottom of the Dye 3 radar station. Some 740 seasonal δ18 cycles were counted, indicating that the core reached back to 1231 AD. Evident in this coring was that as melt water seeps through the porous snow, it refreezes somewhere in the cold firn and disturbs the layer sequence.
|
|
Glacial cirques are found amongst mountain ranges throughout the world; 'classic' cirques are typically about one kilometer long and one kilometer wide. Situated high on a mountainside near the firn line, they are typically partially surrounded on three sides by steep cliffs. The highest cliff often is called a headwall. The fourth side forms the lip, threshold or sill, the side at which the glacier flowed away from the cirque.
|
|
The north side of Sumantri is dominated by tremendous cliffs, part of the Noordwand (Northwall) of the Carstensz Massif, that wrap around to the eastern and western sides of the mountain. Remnants of the once mighty Northwall Firn (now separated into eastern and western parts) cling tenuously to the southern aspects of the peak. It is unlikely that this ice will last for more than the next 15 years.
|
|
The ice must be cut through, broken up, or melted. Tools can be directly pushed into snow and firn (snow that is compressed, but not yet turned to ice, which typically happens at a depth of to );Alley (2000), pp 48–50. this method is not effective in ice, but it is perfectly adequate for obtaining samples from the uppermost layers. For ice, two options are percussion drilling and rotary drilling.
|
|
A SABRE probe consists of a rod that is inserted manually into snow; accelerometer readings are then used to determine the penetrative force needed at each depth, and stored electronically. For testing dense polar snow, a cone penetrometer test (CPT) is use, based on the equivalent devices used for soil testing. CPT measurements can be used in hard snow and firn to depths of 5–10 m.Talalay (2016), pp. 22–23.
|
|
The most recent anti-torque system design is the use of U-shaped blades, made of steel and fixed vertically to the sides of the sonde. Initial implementations ran into problems with thin blades bending too easily, and thick blades providing too much resistance to vertical movement of the sonde, but the final design can generate strong resistance to torque in both firn and ice.Talalay et al. (2014), pp. 210–211.
|
|
Sorge Island () is an island lying just south of The Gullet in Barlas Channel, close east of Adelaide Island. Mapped by Falkland Islands Dependencies Survey (FIDS) from surveys and air photos, 1948–59. Named by United Kingdom Antarctic Place-Names Committee (UK-APC) for Ernst F.W. Sorge, German glaciologist who made the first seismic soundings of the Greenland ice sheet, 1929–31, and developed a theory of the densification of firn.
|
|
Cross section of a cirque glacier showing the bergschrund A bergschrund—the long crack at the foot of the mountain slope—in the Ötztal Alps Open bergschrunds at Mont Dolent A bergschrund (from the German for mountain cleft) or rimaye (from French; ) is a crevasse that forms where moving glacier ice separates from the stagnant ice or firn above.Whittow, John (1984). Dictionary of Physical Geography. London: Penguin, 1984, p. 61. .
|
|
On its left-hand side, the southern branch of the glacier is bounded by the eastern foothills of Pic Coolidge. Hemmed in between these two faces, the firn stream flows initially northeastwards before swinging north just before the two ice streams merge. Rubble first appears on the surface of the southern glacial branch in large quantities in its lower reaches. The two ice streams of the Glacier Noir merge at a height of over .
|
|
A snow patch is a geomorphological pattern of snow and firn accumulation which lies on the surface for a longer time than other seasonal snow cover. There are two types to distinguish; seasonal snow patches and perennial snow patches. Seasonal patches usually melt during the late summer but later than the rest of the snow. Perennial snow patches are stable for more than two years and also have a bigger influence on surroundings.
|
|
Zeitschrift des Deutschen und Oesterreichischen Alpenvereins, Vol. IV, Munich, 1873, pp. 141 ff. The present normal route to the Großer Geiger runs either from the Essener-Rostocker Hut at 2,208 metres, heading in a northerly direction, or from the Kürsinger Hut (2,547 m) in a southerly direction up to the western arête (Geigerschartl col, 3,142 m) of the Geiger and then across its southwestern flank climbing over the firn to the summit cross.
|
|
Tarns are the result of small glaciers called cirques, also known as corries. Cirques form in hollows on mountainsides near the firn line. Eventually, the hollow in which a cirque forms may become a large bowl shape in the side of the mountain, caused by weathering by ice segregation, and as well as being eroded by plucking. The basin will become deeper as it continues to be eroded by ice segregation and abrasion.
|
|
The ice- dammed lake on the northern margin occasionally produces jökulhlaups (also known as glacial lake outburst floods). The icecap is typically thick, exceeding in places. The equilibrium line altitude (ELA) is around on the eastern side of the icecap, above the Leirvatnet outlet. Satellite imagery, including that used by Google Earth, shows extensive exposed firn suggesting the ELA has retreated in recent years in common with other temperate icecaps in Norway.
|
|
A particular feature of the local climate is the instantly freezing rain, covering the northeast-facing surfaces with layers of rime ice. There is little snow in winter, with the island remaining icebound for several months, the ice forms varying from solid firn, through glazed surfaces, to rime ice. Even though Kulusuk lies approximately south of the Arctic Circle, the celestial phenomenon of Aurora borealis can still be observed in the village.
|
|
The East Northwall Firn was a glacier on Mount Carstensz in the Sudirman Range on the island of New Guinea in Papua province, Indonesia. Situated at an elevation of approximately NNW of Puncak Jaya, the highest summit in Oceania. It broke up in three patches in or before 2017.Kathryn Hansen, Glaciers in the Tropics, but Not for Long, at NASA Earth Observatory, February 13, 2018 Puncak Jaya region icecap in 1936.
|
|
They consisted of a thick lens of lake water, which was covered by lake ice, aufeis and glacier ice, and by snow-firn sequence, too. “Aufeis” ledoyoms became independent centers of glaciation with subradial ice outlets. Possible analogies of such an evolution mechanism and pre-glacial lakes are thick water lenses under a 3–4 kilometer- thick unit of the glacier cover at the sites of Dome B and Dome Charlie and the Vostok Station in Eastern Antarctica.
|
|
The Cavistrau is a mountain consisting of two summits in the Glarus Alps, overlooking Brigels and Trun in canton of Graubünden. The mountain belongs to the Brigelser Hörner, of which Cavistrau Grond (3251 m) is the highest and Cavistrau Pign (3219 m), just 230 metres to its east side, the second highest. To its northern side above Val Frisal lies a nameless firn field. The Cavistrau Grond is the highest mountain of the Glarus Alps lying entirely in Graubünden.
|
|
Observations shortly after World War II showed the presence of firn fields and snowfields on the sides of the crater cirque, as well as moraines and glaciers inside the crater. An analysis in 1896 indicated a surface area of 5.5-5.8 km2, but rapidly retreated afterwards. The glaciation has been retreating on account of insufficient snowfall and increasing temperatures. Glacial meltwater dominates the upper part of the rivers descending from Aragats but its importance decreases farther down the valleys.
|
|
At the same time, the surrounding glacier lowers through ablation until the dirt filled crevasse is exposed and the material begins to spread out of top of the glacier. The rest of the glacier continues to lower as the material mound grows higher and taller. Any ice, snow, or firn trapped under the material will be insulated and protected from erosion. It begins forming a conical shape as the sides steepen to an angle that is unstable.
|
|
All of Switzerland's surface area is covered at the levels of Switzerland, cantons, districts, communes, hectares and various spatial units.Construction zones, protected areas, hydrological basins, etc. The registered features are divided into 72 land use and land cover categories in the areas of settlements (buildings and industrial areas, traffic areas, recreational facilities, mines, landfills, construction sites), agriculture (arable land, meadows, pastures, fruit cultivation, vineyards and horticulture), stocked areas (forest, shrub forest, woodland), unproductive areas (watercourses, unproductive vegetation, rocks, sand, boulders, glaciers, firn).
|
|
The Große Möseler (), also called the Mösele, is a mountain, , and thus the second highest peak in the Zillertal Alps after the Hochfeiler (3,509 m). It lies on the Zillertal main ridge which forms the border here between the Austrian state of Tyrol and the Italian province of South Tyrol. Its great size makes it the dominant mountain in the area. Seen from the northwest it appears like a firn-covered dome; but from the northeast as a regularly shaped cone of rock.
|
|
Nivation is the set of geomorphic processes associated with snow patches. The primary processes are mass wasting and the freeze and thaw cycle, in which fallen snow gets compacted into firn or névé. The importance of the processes covered by the term nivation with regard to the development of periglacial landscapes has been questioned by scholars, and the use of the term is discouraged. Nivation has come to include various subprocesses related to snow patches which may be immobile or semi-permanent.
|
|
In 2006 the two remaining parts of the glacier still covered an area of ; in addition there were a couple of smaller firn fields. Since 1990, global warming has seen consistently above-average summer temperatures recorded on the Zugspitze.Garmisch-Partenkirchen Weather Station / Zugspitze 1900 to 2006, DWD Summer snowfalls have become increasingly rare, which damages glaciers, because such snowfalls decrease the energy absorbed by glaciers and interrupt melting processes by increasing their albedo. About of ice melted has melted annually, on average.
|
|
Hawkins Glacier Head (21426626109) A glacier head is the top of a glacier. Although glaciers seem motionless to the observer they are in constant motion and the terminus is always either advancing or retreating. The accumulation zone is found at the highest altitude of the glacier, where accumulation of material is greater than ablation. On a glacier, the accumulation zone is the area above the firn line, where snowfall accumulates and exceeds the losses from ablation, (melting, evaporation, and sublimation).
|
|
The annual equilibrium line separates the accumulation and ablation zone annually. The accumulation zone is also defined as the part of a glacier's surface, usually at higher elevations, on which there is net accumulation of snow, which subsequently turns into firn and then glacier ice. Part of the glacier where snow builds up and turns to ice moves outward from there. The glacier head is the highest upslope edge of an alpine glacier or the upslope end of the zone of accumulation.
|
|
The mountains of Central Papua are being formed as the Australian and Pacific Plates collide, resulting in both subduction and uplifting. The rocks at the surface for the peaks in this range are made of limestone. As a result, even though the summit block of the peak looks extremely daunting, it is a fairly easy scramble. Due to the melting of the Northwall Firn from the SE peak of Ngga Pulu, this summit is now the highest point of the north ridge of Mount Carstensz.
|
|
A deep gully descends along the north-western slopes that holds perennial firn. To the west is situated the valley of the Musala Bistritsa, a tributary of Bulgaria's longest river, the Iskar and Musala refuge; to the north-east is situated the Saragyol Cirque that contains three glacial lakes. Deno is located in the vicinity of the ski runs of Borovets and the cabin lift to Yastrebots refuge, which make it easily accessible. In winter some of the tourist tracks are exposed to avalanches.
|
|
The gallery held an exhibition of "London as seen by an Italian", featuring paintings by Piero Sansalvadore. According to The Antique Dealers Blog, "Connell is well known amongst art historians as a ‘Fine Art’ dealer – one who emerged from the picture frame making trades in the middle decades of the 19th century" and continued in business at least until the 1930s. One of their catalogues was also of porcelain. One of their picture frame labels identifies the firn as having been established in 1862.
|
|
Firn has the appearance of wet sugar, but has a hardness that makes it extremely resistant to shovelling. Its density generally ranges from 0.4 g/cm³ to 0.83 g/cm³, and it can often be found underneath the snow that accumulates at the head of a glacier. Snowflakes are compressed under the weight of the overlying snowpack. Individual crystals near the melting point are semiliquid and slick, allowing them to glide along other crystal planes and to fill in the spaces between them, increasing the ice's density.
|
|
The surveyed length and depth of Booming Ice Chasm is 961 metres and 179 metres respectively and is ranked the 61st longest and 30th deepest cave in Canada. On the upper descending part of the cave, near the entrance, is a dense, steeply downward sloping sheet of ice, dropping approximately 140 metres. This is referred to as an ice fall or cascading glacier-like ice block and is controlled by cave morphology and the local climate. Specifically, it is formed by firn and seepage water.
|
|
Sure-footed and experienced climbers can also climb the Hohe Munde from Telfs - branching off in Straßberg to the saddle of the Niedere Munde - via the western arête, a route graded as UIAA I. There are several climbing routes up the north and south faces below both the east and west tops, some of which are difficult. A ski tour is possible over the steep (up to 45 degrees) east side in the spring. However, this requires safe firn conditions and a very early start.
|
|
R. W. Solomon. By 1937, Mohr was in charge of the Federal Art Project for the Cincinnati public schools and painted the mural for the Linwood School. Mohr was the only woman in the group known as the New Group of Cincinnati Artists, which included Myer Abel, Paul G. Craft, Edward Firn, William Gebhardt, Harry Gothard, Mohr, Leo Murphy, Mathias Noheimer, and Zoellner. In 1937, the group was invited to do shows at the Art Association of Richmond, Indiana and at the University of Chattanooga.
|
|
101-112 #Anderson, T. M., Griffith, D. M., Grace, J. B., Lind, E. M., Adler, P. B., Biederman, L. A., Blumenthal, D. M., Daleo, P., Firn, J., Hagenah, N., Harpole, W. S., MacDougall, A. S., McCulley, R. L., Prober, S. M., Risch, A. C., Sankaran, M., Schütz, M., Seabloom, E. W., Stevens, C. J., Sullivan, L. L. & 2 others, Apr 1 2018. Herbivory and eutrophication mediate grassland plant nutrient responses across a global climatic gradient. Ecology. 99, 4, p. 822-831 # Borer, E.T. et al.
|
|
Andres Hiiemäe: Ülikooli mäetipu vallutuse raske tee Universitas Tartuensis (in Estonian) The summit has been reached by Estonian climbing groups twice, on 3 August 1982 (group: Kalev Muru, Kalle Hansen, Anu Kallavus, Andres Paris, Jaan Künnap and Kalle Aedviir), and on 31 July 2012 (group: Andres Hiiemäe, Erik Jaaniso, Marko Aasa, Priit Rooden, Merili Simmer, Kristjan-Erik Suurväli, Tõnu Põld, Priit Simson, Priit Joosu, Sven Oja).Brief (unofficial) History of Mountaineering and Climbing Sport in Estonia, History of "Firn" Included Firn (version from May 2013)Inga Külmoja: Remote Peak Named after Tartu Conquered Again University of Tartu Blog, August 24, 2012 It was first thought to rise to 6,350 meters, hence its suitability to commemorate the 350th anniversary of the university,Mountaineers From Estonia to Rise to University of Tartu, Parrot Peaks estonia.eu, 13 July 2012 but according to the GPS-measurements made on the second ascent in 2012 the peak was actually found to be 6,258 m high. At the time of the first conquest it was one out of five peaks in Soviet Union that was named after a university and the highest of them.
|
|
Finally, many height indications on these maps may be not up-to- date, while glacier and firn melt has decreased the height of both peaks and key cols, quite dramatically. For example, until 2009, the Col des Maisons Blanches which lies on the Corbassière Glacier was measured to be 3,418 m, while the more recent maps (2012) show it to be 3,404 m high. This is the key col for the Combin de Corbassière (3,716 m), which, thanks to the retreat of the glacier, now appears on the list with a prominence of 312 m.
|
|
Collets are effective in firn but less so in ice, so core dogs, also known as core catchers, are often used for ice cores. A typical ice drill core dog has a dog-leg shape, and will be built into the drill head with the ability to rotate, and with a spring supplying some pressure against the core. When the drill is lifted, the sharp point of the core dog engages and rotates around, causing the core to break. Some core dogs have a shoulder to stop them from over-rotating.Talalay (2012), pp. 28–29.
|
|
When drilling in ice, the hole may be drilled dry, with no mechanism to dispose of the cuttings. In snow and firn this means that the cuttings simply compact into the walls of the borehole; and in coring drills they also compact into the core. In ice, the cuttings accumulate in the space between the drillpipe and the borehole wall, and eventually start to clog the drill bit, usually after no more than 1 m of progress. This increases the torque needed to drill, slows down progress, and can cause the loss of the drill.
|
|
Their base was the Johannis Hut lying at 2,121 metres in the valley of the Upper Dorfertal. Their route initially followed the Dorferbach upstream to the middle of the very heavily crevassed Dorferkees at a height of about 2,700 metres and then swung west over firn at a gradient of 30° to the so-called Ostsporn (East Spur). They scaled this relatively difficult rock climbing route, today classed as UIAA climbing grade II, to the summit. This entailed negotiating some critical sections which almost led to a fall.
|
|
The first reference to Inuit having multiple words for snow is in the introduction to Handbook of American Indian languages (1911) by linguist and anthropologist Franz Boas. He says: The essential morphological question is why a language would say, for example, "lake", "river", and "brook" instead of something like "waterplace", "waterfast", and "waterslow". English has many snow-related words,Some of them are borrowed from other languages, like firn (German), névé (French), penitentes (Spanish) and sastrugi (Russian). but Boas's intent may have been to connect differences in culture with differences in language.
|
|
Ablation zone or ablation area refers to the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass due to melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, avalanche, and any other ablation. The equilibrium line altitude (ELA) or snow line separates the ablation zone from the higher-altitude accumulation zone. The ablation zone often contains meltwater features such as supraglacial lakes, englacial streams, and subglacial lakes. Sediments dropped in the ablation zone forming small mounds or hillocks are called kames.
|
|
The firn-covered Eastern Simonyspitze is important from a mountaineering perspective, but is not often climbed. The normal route along the southeastern arête is rated as UIAA grade II. The start point for the roughly 4 hour ascent is the Essener-Rostocker Hut (2,208 m) in the Maurertal valley. Other routes run up the south flank (II), east flank (III-), northeastern arête (III) and Western Hanging Glacier (Westlichen Hängegletscher, III+). The North Face (IV) is the most difficult climb and may also be reached via the Western Hanging Glacier from the Warnsdorfer Hut (2,336 m) in the Krimmler Achental.
|
|
Fibreglass and HDPE casing has become more common, with junctions sealed with PTFE tape, but leaks are frequent. Heat fusion welding for HDPE casing is a possible solution. To seal the bottom of the casing, water can be pumped to the bottom of the hole once the casing is set, or a thermal head can be used to melt ice around the casing shoe, creating a seal when the water freezes again. Another approach is to use a hotpoint drill, saturating the snow and firn with melted water, which will then freeze and seal the borehole.
|
|
The Southern Schneeferner on 28 August 2003, immediately after the record heat wave The Southern Schneeferner (Südlicher Schneeferner) once covered the entire southwestern part of the Zugspitzplatt. By 2006 only an area of some was left and its ice sheet, with an average thickness of less than , was thin.Südliche Schneeferner - Topographie at www.lrz.de. Accessed on 23 Dec 2010 At the end of the 20th century the glacier had split up into a southeastern part below the Wetterwandeck and a northwestern area below the Wetterspitzen, which later divided into the last remaining large sheet of ice and several smaller firn fields.
|
|
Ernst Sorge was a member of the Alfred Wegener Expedition to Eismitte in central Greenland from July 1930 to August 1931. He hand-dug a 15 m deep pit adjacent to his beneath- the-surface snow cave, which served as his living quarters during his seven- month-long wintering-over stint. Sorge was the first to systematically and quantitatively study the near-surface snow/firn strata from inside his pit. After meticulous examination of the structural features and careful measurement of continuous density and other physical properties within the pit profile, Sorge determined the characteristics of the individual limits of annual snow accumulation.
|
|
There are arêtes running away from the top in all four direction of the compass. Seen from the northeast, the Großer Bärenkopf, has the shape of a wide, prominent, firn- covered mountain. From the other directions it looks like a rocky peak. The mountain was first climbed on 18 September 1869 by Munich Alpinists Karl Hofmann, Prague merchant, Johann Stüdl, and mountain guides Thomas Groder and Josef Schnell from Kals am Großglockner on their exploratory tour, that took them on the same day to the neighbouring peaks of the Hinterer Bratschenkopf and Klockerin to the north.
|
|
Albert Valley () is a hanging valley between Conway Peak and Wendler Spur in the central Apocalypse Peaks of Victoria Land. The valley opens north to Barwick Valley. Named in 2005 by the Advisory Committee on Antarctic Names after Mary R. Albert, Cold Regions Research and Engineering Laboratory, Hanover, NH, who conducted field and laboratory research to characterize ice core, firn, and snow properties from Siple Dome, from the US-ITASE traverses of West Antarctica, and from East Antarctic megadunes, 1996–2003; Member, 2002- , Polar Research Board, National Academy of Sciences; Chair 2003- , U.S. National Committee for the International Polar Year, 2007–08.
|
|
There are some processes that mix water from different times into the same depth in the ice core, such as firn production and sloped landscape floes. Lisiecki and Raymo (2005) used measurements of δ18O in benthic foraminifera from 57 globally distributed deep sea sediment cores, taken as a proxy for the total global mass of glacial ice sheets, to reconstruct the climate for the past five million years. This record shows oscillations of 2-10 degrees Celsius over this time. Between 5 million and 1.2 million years ago, these oscillations had a period of 41,000 years (41 kyr), but about 1.2 million years ago the period switch to 100 kyr.
|
|
Classification of snow on the ground comes from two sources: the science community and the community of those who encounter it in their daily lives. Snow on the ground exists both as a material with varying properties and as a variety of structures, shaped by wind, sun, temperature, and precipitation. Hoar frost on the snow surface from crystallized water vapor emerging on a cold, clear night Cornice on an alp in France Snowdrift in Gloucestershire Sastrugi in Norway Alpine firn in Austria Penitentes under the night sky of the Atacama Desert Suncups in England Packing snow being rolled into a large snowball in Oxford, England.
|
|
The Hoher Riffler is a 3,231 metreAustrian Map online 1:50.000 (ÖK 50) of the BEV high mountain in the Zillertal Alps, on the eastern part of the main chain of the Tux (Tuxer Hauptkamm), in the Austrian state of Tyrol. The peak is firn-covered on its northern side, but from the south it looks like a rocky summit. Ridges run from the top towards the southwest, north, northeast and southeast, some of them carrying approach paths. The summit is easily attained from the mountain hut of Spannagelhaus to the west or the Friesenberghaus to the south and, as a result, is often visited.
|
|
See The Glacier Noir with Pic Coolidge and the Barre des Écrins The Glacier Noir is fed from two high-altitude firn basins. The northern branch (branche septentrionale) is in turn fed from the bowl below the Col des Avalanches, at the foot of Pic Coolidge and the Barre des Écrins, the southwesternmost four-thousander of the Alps. From here it flows below the south face of the Crête de l'Encoula (also: Crête de l'Encula), a crest that runs from the Barre to the Pointe du Serre Subeyran. The great majority of the rubble that covers the lower section of the glacier is transported from its northern branch.
|
|
From its head at over high to its foot, currently (2010) at about (2002: ), the Glacier Blanc descends through a height of around 1,600 metres. The firn line on the Glacier Blanc, which separates the accumulation zone from the ablation zone, lies on the northern slopes at a height of about and on the southern flanks at about .Tim Stott, Professor of Physical Geography & Outdoor Education, Liverpool John Moores University The glacier's mass balance, an indicator of its health, has not been fully investigated. The Glacier Blanc drains via the Torrent du Glacier Blanc, the Gyr, the Gyronde, the Durance, and finally the Rhône into the Mediterranean Sea.
|
|
For snow and firn, where the core material may be at risk of falling out of the bottom of the core barrel, a basket catcher is a better choice. These catchers consist of spring wires or thin pieces of sheet metal, placed radially around the bottom of the core barrel and pressed against the side of the barrel by the core as the drill descends around it. When the drill is lifted, the ends of the catcher engage with the core and break it from the base, and act as a basket to hold it in place while it is brought to the surface.Talalay (2012), p. 35.
|
|
Casing, or lining a hole with a tube, is necessary whenever drilling operations require that the borehole be isolated from the surrounding permeable snow and firn. Uncased holes can be drilled with fluid by using a hose lowered into the hole, but this is likely to lead to increased drilling fluid consumption and environmental contamination from leaks. Steel casing was used in the 1970s, but rust from the casing caused damage to the drills, and the casing was not sealed, leading to fluid leaks. There were also problems with the casing tubes not being centered, which caused damage to the drill bit as it was lowered through the casing.
|
|
In 1880 Compton became a member of the Royal Academy, London. Besides his work as a painter he also became well known as a book illustrator for the German and Austrian Alpine Association (DAV) with titles such as "In the high mountains" by Emil Zsigmondy (1889), "About Fels and Firn" by H. Hess (1901) and "Mountaineering in Pictures" by Alfred Steinitzer (1913). In England he was also in demand as an illustrator providing pictures for a range of titles (see below). Malcesine on Lake Garda Monte Baldo (1913) In 1909 Compton accompanied his friend, the mountaineer Karl Blodig on many tours in the Silvretta mountains.
|
|
There was a follow-up U.S. GISP2 project, which drilled at a glaciologically better location on the summit of the ice sheet. This hit bedrock (and drilled another 1.55 m into bedrock) on July 1, 1993 after five years of drilling, while European scientists produced a parallel core in the GRIP project. GISP2 produced an ice core 3053.44 meters in depth, the deepest ice core recovered in the world at the time.The GISP2 Ice Coring Effort, National Climatic Data Center The location of the GISP2 drilling was revisited annually during summer campaigns to investigate the post-depositional properties of gasses and aerosols in the firn.
|
|
Another method is to correlate radionuclides or trace atmospheric gases with other timescales such as periodicities in the earth's orbital parameters. A difficulty in ice core dating is that gases can diffuse through firn, so the ice at a given depth may be substantially older than the gases trapped in it. As a result, there are two chronologies for a given ice core: one for the ice, and one for the trapped gases. To determine the relationship between the two, models have been developed for the depth at which gases are trapped for a given location, but their predictions have not always proved reliable., pp. 2530–2531.
|
|
In 1979, the initial Dye-3 deep bedrock drilling was started using a 22.2 cm diameter CRREL thermal (US) coring drill to produce an 18 cm diameter access hole, which was cased, to a depth of 77 m. The large diameter casing was inserted over the porous firn zone to contain the drilling fluid. After working out various logistical and engineering problems related to the development of a more sophisticated drilling rig, drilling to bedrock at Dye 3 began in the summer of 1979 using a new Danish electro-mechanical ice drill yielding a 10.2 cm diameter core. From July to August 1979 using ISTUK, 273 m of core was removed.
|
|
They appear from the north as a stubby, cone-shaped, firn-covered dome, but from the east as a forbidding, dark rock face. Sharp, prominent ridges radiate from the peaks to the northeast and southwest, along the main crest of the mountain range. The twin peaks are the highest points in the summer skiing area of the Hintertux Glacier and, since the end of the 1990s, have been accessible from Hintertux on cable cars and ski lifts; which makes them a popular destination for day trippers. The north summit was first conquered in 1867 by Dr. Berreitter, the south summit on 7 September 1872 by the brothers, Max and Richard von Frey from Salzburg.
|
|
Also, the deepest points in connecting ridges are not always survey points with spot elevations, where heights have to be estimated from contour lines. For example, maps often provide heights for the place where a route passes over a ridge rather than for the lowest point of that pass. Finally, many height indications on these maps are from quite old measurements, while glacier and firn melt has decreased the height of both peaks and key cols, sometimes quite dramatically. For example, in 1930, glacier-capped Cima Tosa was the highest mountain of the Brenta Dolomites at 3,173 m, but now is around 3,140 m high and some 10 m lower than its rocky neighbor Cima Brenta (3,151 m).
|
|
Wildspitze is on a ridge called Weißkamm ("white ridge") that joins the main chain of the Alps at the Weißkugel. Its north and west flanks form the end of the Pitz valley, while the south and east flanks rise above the upper ends of the Ötztal. The mountain has twin peaks, with a rocky south summit (3768 mBundesamt für Eich- und Vermessungswesen, Austrian Map online or by most other sources 3770 mThe Austrian Alpine Club's Alpine Club map of the Ötztal AlpsWalter Klier, Ötztaler Alpen: ein Führer für Täler, Hütten und Berge, Rother, Munich, 14th print, 2006.) and a firn-covered north summit that is ca 3,760 m.Bergsteiger, January 2001, page 25.
|
|
East of the summit cone, a separate steep niche glacier, Glaciar Oriental, long and having a gradient of , flows down the mountainside from about ; it contains many crevasses and seracs and is the most difficult glacier to climb. Glacier Oriental had a surface area of about in 1958, which makes the total area of glaciers and firn field on Citlaltépetl about . No earlier historical record of glacier tongue activity (advance or recession) is known for Citlaltépetl's glaciers. Although the Gran Glaciar Norte ice cap is covered with snow, it is possible to see the seven outlet glaciers on the irregular west margin of the ice cap, especially Glaciar de Jamapa and Glaciar Occidental.
|
|
Leaf springs have been found to be so effective that they can prevent rotation even in heavy drills running at full power. Skate antitorque systems have blades attached to vertical bars which are pushed against the borehole wall; the blades dig into the wall and provide the anti- torque. Skates can be built with springs which allow them to keep the blades pressed against the wall in an irregular borehole, and to prevent problems in narrower parts of the borehole. Although skates are a popular design for anti- torque and have been used with success, they have difficulty preventing rotation in firn and at boundaries between layers of different densities, and can cause problems when drilling with high torque.
|
|
"Sugar snow" as a layer in a snowpack Depth hoar crystals, imaged with light and with scanning electron microscopy Sugar snow - panoramio Depth hoar, also called sugar snow or temperature gradient snow (or TG snow), are large snow- crystals occurring at the base of a snowpack that form when uprising water vapor deposits, or desublimates, onto existing snow crystals. Depth hoar crystals are large, sparkly grains with facets that can be cup-shaped and that are up to 10 mm in diameter. Depth hoar crystals bond poorly to each other, increasing the risk for avalanches. The formation of depth hoar in Arctic or Antarctic firn can cause isotopic changes in the accumulating ice.
|
|
The Watzmann Glacier is located below the famous east face of the Watzmann in the Watzmann cirque and is surrounded by the Watzmanngrat arête, the Watzmannkindern and the Kleiner Watzmann. The size of the glacier reduced from around in 1820 until it split into a few fields of firn, but between 1965 and 1980 it advanced significantly again and now has an area of . Above and to the west of the icefield lie the remains of a JU 52 transport-bomber that crashed in October 1940. The Eiskapelle in summer Amongst the other permanent snow and icefields the Eiskapelle ("Ice Chapel") is the best known due to its easy accessibility from St. Bartholomä.
|
|
The problem is more acute at locations where accumulation is high; low accumulation sites, such as central Antarctica, must be dated by other methods. For example, at Vostok, layer counting is only possible down to an age of 55,000 years. When there is summer melting, the melted snow refreezes lower in the snow and firn, and the resulting layer of ice has very few bubbles so is easy to recognise in a visual examination of a core. Identification of these layers, both visually and by measuring density of the core against depth, allows the calculation of a melt-feature percentage (MF): an MF of 100% would mean that every year's deposit of snow showed evidence of melting.
|
|
The Große Wiesbachhorn seen from the Fusch side The Großes Wiesbachhorn () is a mountain in the federal state of Salzburg, Austria and, at (according to other sources ), is the third-highest peak of the Hohe Tauern range. Its entirely free-standing firn-capped summit forms the main peak of the Fusch/Kaprun chain and is often viewed in Alpine literature as a rival of the Großglockner. The great slope on its eastern and southeastern side plunges about 2,300 metres to the Fuscher Ache - one of the greatest height differences between mountaintop and valley floor in the Eastern Alps. Of alpinistic significance was the first ascent of the Northwest Face (Nordwestwand) on 15 July 1924 by Franz Riegele and Willo Welzenbach.
|
|
For deep holes, a drilling fluid is required to maintain pressure in the borehole and prevent the hole from closing up because of the pressure the ice is under; a drilling fluid requires additional heavy equipment to circulate and store the fluid, and to separate the circulated material. Any circulation system also requires the upper part of the hole, through the snow and firn, to be cased, since circulated air or fluid would escape through anything more permeable than ice. Commercial rotary rigs are not designed for extremely cold temperatures, and in addition to problems with components such as the hydraulics and fluid management systems, they are designed to operate outdoors, which is impractical in extreme environments such as Antarctic drilling.Talalay (2016), p. 97.
|
|
The Gleirscher Fernerkogel lies a good seven kilometres as the crow flies northeast of Längenfeld in the Ötztal valley and just under 7 km southwest Praxmar in the Lüsenstal valley. To the east two glaciers climb the mountain to a height of 3,100 metres. North of the east ridge is the Gleirschferner glacier; to the south is the Weißkogelferner, rapidly disappearing as a result of global warming, whose firn field is now only just under 300 metres long. Neighbouring peaks are the Hintere Grubenwand (3,175 m) on the east ridge, separated by the col of Roßkarscharte (3,053 m); the Winnebacher Weißkogel (3,185 m) to the south; and the Sonnenwände peaks to the north, whose highest top is the Hintere Sonnenwand (3,112 m).
|
|
Firn and snow fields were reported in the middle 20th century on the El Tatio volcanic group, at elevations of . The region is too dry to support glaciers today, but in the past higher moisture allowed their formation on mountains of this part of the Andes; glacially eroded mountains and moraines testify to their existence in the form of large valley glaciers. A large moraine complex, including both terminal structures and well-developed lateral moraines, can be found north of the geyser field and reflects the existence of a long glacier, the longest valley glacier in the region. Two more moraine systems extend westward both northeast and southeast of El Tatio, and the terrain surrounding the geyser field is covered by sands that are interpreted as glacial outwash sands.
|
|
The main problem with the RAM drill is a loss of air circulation in firn and snow, which might be addressed by using reverse air circulation, via a vacuum pump drawing air up through the hose. As of 2017 IDDO is planning a revised design for the RAM drill to reduce the weight of the drill, which is currently 10.3 tonnes. Other flexible drill stem designs have been considered, and in some cases tested, but as of 2016 none had been successfully used in the field. One design suggested using hot water to drill via a hose, and replacing the drillhead with a mechanical drill for coring once the depth of interest is reached, using the hot water both to hydraulically power the down hole motor, and to melt the resulting ice cuttings.
|
|
The rock fell some vertically before landing on Glacier 511 and sliding nearly down its surface, accumulating a large volume of firn snow as it went. The initial ice- rock avalanche volume was at least 25 million cubic metres (33 million yd3), and grew rapidly in size as it fell down the steep Llanganuco valley, picking up large volumes of dirt, loose glacial moraine, water and uprooted trees. With area soils saturated near the end of the rainy season, and the large amount of snow and ice scraped off the glacier surface, the avalanche quickly liquefied into a fluid, fast-moving mudflow. The maximum volume of the mudflow was as much as 100 million cubic metres (130 million yd3), and it reached speeds of up to per hour.
|
|
The first systematic study of snow and firn layers was by Ernst Sorge, who was part of the Alfred Wegener Expedition to central Greenland in 1930–1931. Sorge dug a 15 m pit to examine the snow layers, and his results were later formalized into Sorge's Law of Densification by Henri Bader, who went on to do additional coring work in northwest Greenland in 1933., pp. 5–6. In the early 1950s, a SIPRE expedition took pit samples over much of the Greenland ice sheet, obtaining early oxygen isotope ratio data. Three other expeditions in the 1950s began ice coring work: a joint Norwegian-British-Swedish Antarctic Expedition (NBSAE), in Queen Maud Land in Antarctica; the Juneau Ice Field Research Project (JIRP), in Alaska; and Expéditions Polaires Françaises, in central Greenland.
|
|
North of the Alphubel is the higher Täschhorn, the southernmost top of the Mischabel, from which it is separated by the saddle of Mischabeljoch (3,847 m), while the ridge to the south is less prominent running via the Alphubeljoch (3,771 m) to the Feechopf (3,888 m) and Allalinhorn. While the terrain drops steeply into the Mattertal valley to the west, the east side is flat and, compared to its neighbours, almost smooth. The characteristically flat summit of the Alphubel is mostly covered with firn and has, in addition to the main summit, a northern top of 4,188 m, which barely rises above the flat summit area. From the Alphubel a prominent, ice-free, rocky arête, the Rotgrat, strikes westwards down to the Täsch Hut (Täschhütte, 2,701 m), while the main, north-south, ridge and an unnamed arête running northeast are largely covered by ice.
|
|
Measurements from Antarctic ice cores show that before industrial emissions started atmospheric mole fractions were about 280 parts per million (ppm), and stayed between 260 and 280 during the preceding ten thousand years. Carbon dioxide mole fractions in the atmosphere have gone up by approximately 35 percent since the 1900s, rising from 280 parts per million by volume to 387 parts per million in 2009. One study using evidence from stomata of fossilized leaves suggests greater variability, with carbon dioxide mole fractions above 300 ppm during the period seven to ten thousand years ago, though others have argued that these findings more likely reflect calibration or contamination problems rather than actual variability. Because of the way air is trapped in ice (pores in the ice close off slowly to form bubbles deep within the firn) and the time period represented in each ice sample analyzed, these figures represent averages of atmospheric concentrations of up to a few centuries rather than annual or decadal levels.
|
|
Weighing the cylinder full of snow and subtracting the weight of the empty cylinder gives the snow weight; samplers usually have lengthwise slots to allow the depth of the snow to be recorded as well, though a sampler made of transparent material makes this unnecessary. The sampler must grip the snow well enough to keep the snow inside the cylinder as it is removed from the snow, which is easier to accomplish with a smaller diameter cylinder; however, larger diameters give more accurate readings. Samples must avoid compacting the snow, so they have smooth inner surfaces (usually of anodized aluminium alloy, and sometimes waxed in addition) to prevent the snow from gripping the sides of the cylinder as it is pushed in. A sampler may penetrate light snow under its own weight; denser snow pack, firn, or ice, may require the user to rotate the sampler gently so that the cutting teeth are engaged.
|
|
View from the summit of the Lusen of the Sommerweg ascent in the (south-)west Whilst the Anterior Bavarian Forest only exceeds 1,000 m in a few places (for example, the Brotjacklriegel 1,016 m, Einödriegel 1,121 m, Breitenauriegel 1,114 m, Vogelsang 1,022 m, Hirschenstein 1,092 m and Pröller 1,048 m), most of the summit regions in the High Bavarian Forest are over 1300 up to 1,400 m (Plöckenstein 1,378 m, Dreisesselberg 1,333 m, Lusen 1,371 m, Großer Rachel 1,453 m, Kleiner Rachel 1,399 m, Kaitersberg 1,133 m, Großer Falkenstein 1,315 m, Großer Osser 1,293 m, Zwercheck 1,333 m, Großer Arber 1,456 m). In particular, those regions of the High Bavarian Forest were covered by snow and ice fields during the Ice Age that also left their traces. Here, on the vast plateaux there were rather extensive firn fields rather than long glacial snouts. The thickness of the glacier ice at 1,050 m was about 125 metres.
|
|
In the upper 80 m of the ice sheet, the firn or the snow gradually compacts to a close packing of ice crystals of typical sizes 1 to 5 mm. Crystal size distributions were obtained from fifteen vertical thin sections of 20 cm × 10 cm (height × width) and a thickness of 0.4 ±0.1 mm of ice evenly distributed in the depth interval 115 – 880 m. Peak sizes with depth were ~1.9 mm 115 m, ~2.2 mm 165 m, ~2.8 mm 220 m, ~3.0 mm 330 m, ~3.2 mm 440 m, ~3.3 mm 605 m, whereas mean sizes with depth were ~1.8 115 m, ~2.2 mm 165 m, ~2.4 mm 220 m, ~2.8 mm ~270 m, ~2.75 mm 330 m, ~2.6 mm ~370 m, ~2.9 mm 440 m, ~2.8 mm ~490 m, ~2.9 mm ~540 m, ~2.9 mm 605 m, ~3.0 ~660 m, ~3.2 mm ~720 m, ~2.9 mm ~770 m, ~2.7 mm ~820 m, ~2.8 mm 880 m. And, here again as with Dye 3, steady state in grain growth was reached and continued through the post-glacial climatic optimum.
|
|