Aletsch glacier
| Great Aletsch Glacier | ||
|---|---|---|
 Big Aletsch glacier from Eggishorn |
||
| location | Canton of Valais , Switzerland | |
| Mountains | Bernese Alps | |
| Type | Valley glacier | |
| length | 22.75 km (2007, including Jungfraufirn) | |
| surface | 81.7 km² (including source glacier) | |
| Exposure | South-east from Konkordiaplatz | |
| Altitude range | 4160 m above sea level M. - 1575 m above sea level M. (2007) | |
| Tilt | ⌀ 6 ° (11%) | |
| Coordinates | 648 269 / 142 636 | |
|
||
| drainage | Massa , Rhone | |
| particularities | Longest and largest alpine glacier | |
The Great Aletsch Glacier is the largest and longest glacier in the Alps in terms of area . It is located on the southern roof of the Bernese Alps in the Swiss canton of Valais . The length of the glacier is 22.75 km, the area including the source glacier is given as 81.7 km². The Aletsch Glacier drains over the Massa into the Rhone . The area of the entire catchment area of the Massa is 195 km², of which in 1973 about two thirds were glaciated. Often the Upper and Middle Aletsch Glaciers are included in the area specification, as these were previously connected to the Great Aletsch Glacier. The total area covered by glaciers, including these glaciers, was about 128 km² in 1973, and an area of 163 km² is assumed for 1863.
Origin at Konkordiaplatz
The origin of the Great Aletsch Glacier lies in the Jungfrau region, which is around 3800 m high . On Konkordiaplatz ( 645,905 / 150101 ) , a 6 km² big and little inclined ice, flowing three powerful Firnströme together:
- The Grosse Aletschfirn , which flows along the northern foot of the Aletschhorn and Dreieckhorn, flows from the west . The Grosse Aletschfirn is fed from the north by three other important firns, namely the Ebnefluhfirn , the Gletscherhornfirn and the Kranzbergfirn . All of these firns start at around 3800 m above sea level. M. Including the Ebnefluhfirns has the Aletschfirn km a length of 9 to Konkordiaplatz and is averaging nearly 1.5 km wide. To the west is the Grosse Aletschfirn over the 3173 m above sea level. M. high glacier pass of the Lötschenlücke connected with the Lang glacier, which flows into the Lötschental .
- The Jungfraufirn flows from the northwest , which is the straight continuation of the Aletsch Glacier, but the shortest of the three tributary glaciers . It has its origin on the southern flank of the Mönch , on the Jungfraujoch and on the eastern flank of the Jungfrau. The Jungfraufirn covers a distance of almost 7 km to Konkordiaplatz and is flanked by the Kranzberg in the west and the Trugberg in the east. Its upper part is 2 km wide, and further down it is a good 1 km wide.
- The Ewigschneefeld flows from the north, starting on the eastern flank of the Mönch and flowing in an arc, flanked by the Trugberg in the west and the Gross Fiescherhorn and the Grünhorn in the east, to Konkordiaplatz. Up to this point it is about 8 km long and an average of 1.2 km wide. The confluence with Konkordiaplatz takes place over a steep slope with a gradient of 25 to 30%; the glacier is very rugged here. To the north, the Ewigschneefeld is connected to the catchment area of the Lower Grindelwald Glacier via the firn-covered pass of the Untere Mönchsjoch ( 3529 m above sea level ) . There is a connection to the Jungfraufirn through the Obere Mönchsjoch ( 3627 m above sea level ) between the Mönch and the Trugberg. Furthermore, the much smaller Grüneggfirn (3 km long and an average of 600 m wide) flows from the east at Konkordiaplatz . This is connected to the east via the glacier pass of the Grünhornlücke ( 3280 m above sea level ) with the Fiescher glacier .
Further course
From Konkordiaplatz, the ice stream moves with a width of about 1.5 km and at a speed of up to 180 meters per year to the southeast in the direction of the Rhone Valley , bordered by the Dreieckhorn in the west and the Great Wannenhorn in the east. It then draws a large right-hand bend and turns more and more to the southwest, now separated from the Rhone Valley by the ridge of the Eggishorn and Bettmerhorn . The lowest part of the Great Aletsch Glacier is largely covered by the bed load from lateral and central moraines . The glacier tongue is currently at around 1,560 meters above sea level, well below the local tree line . The Bach Massa rises from it , which flows into the Rhone (Rotten) after the Massa Gorge and a use in a hydroelectric power station, in Bitsch, above Naters .
The Great Aletsch Glacier has considerable ice thicknesses. At Konkordiaplatz the glacier has an ice thickness of more than 900 meters, towards the south the thickness of the ice gradually decreases to around 150 m. Characteristic are the two dark moraine tracks almost in the middle of the Aletsch Glacier, which extend from Konkordiaplatz along the entire length to the tongue area. It is the central moraines that separate the ice of the three main peaks. The western central moraine is also called the Kranzberg moraine , the eastern one is called the Trugberg moraine .
Glacier fluctuations
At its peak during the Little Ice Age around the middle of the 19th century, the Great Aletsch Glacier extended around 2.5 km further down the valley. Due to the general warming since around 1870, it has lost massively in volume, especially below the Konkordiaplatz, and freed up areas of several square kilometers both on the sides and in the tongue area. The former glacier level, which has been the highest in modern times, can be estimated from the side moraines, which are still almost without vegetation. Since 1850 the ice thickness has decreased by more than 100 m. In the past, the ice flows of the Oberaletsch Glacier and the Mittelaletsch Glacier were directly connected to the Great Aletsch Glacier.
In the depression between the Strahlhorn and the Eggishorn lies the Märjelensee , which was dammed up to form a glacier edge lake in the 19th century when the glacier was high. Its repeated sudden eruptions through crevasses caused severe flooding of the Massa towards the Rhone Valley.
Due to its large mass, the glacier is relatively immune to short-term climatic fluctuations . While many other glaciers advanced from the late 1970s to the early 1980s, the Aletsch Glacier hardly reacted to the temporary cooling - just as little as it did to the warm years since 1983. Due to the increasingly extreme heat of recent years, however, it is now stretching - like all other alpine glaciers - significantly stronger back.
The relative inertia in its reactions to climatic fluctuations also makes the Aletsch Glacier an ideal study object for researching climate development in the Alpine region . The fluctuations in length of the Aletsch Glacier in the past should even allow a reconstruction of all major climatic changes of the last 3200 years. The different stages of length of the Aletsch Glacier in the past are determined by radiocarbon dating of fossil tree trunks which the glacier must have crossed once during an earlier advance and which are now released again during its current retreat. The finding of fossil soils and roots guarantees that the place of discovery is also the place where the fossil tree grew. By counting the annual rings of the recovered trunks, it is even possible to determine the period during which the Aletsch Glacier did not reach the site. Using this method, it was established that the Aletsch Glacier was until about 1200 BC. BC must have been a lot smaller than at the end of the 20th century. For the years from about 1200 to 1110 BC. BC, 850 to 750 BC And 350 to 250 BC Advances have been established. The Aletsch Glacier is from 900 to 400 BC. However, it was smaller than at the end of the 20th century, as well as from around 100 BC. Until the year 250. Around the year 300 a glacier length comparable to that of the highest level in the 19th century can be determined.
According to the last study by the University of Erlangen-Nuremberg (June 2020), the surface of the Great Aletsch Glacier melted by more than five meters per year in the lower layers between 2001 and 2014.
tourism
The Aletsch Glacier was considered a special attraction for travelers and a welcome object of investigation for researchers from early on. Research stations have been on the Jungfraujoch since 1937 and on the Riederfurka above the Riederalp since 1976 . The mountain ridge between the Riederhorn and the Eggishorn is particularly well developed by numerous cable cars and offers very beautiful views of the tongue area and the lower part of the glacier. With the construction of the Jungfrau Railway on the Jungfraujoch (on the Sphinx 3571 m above sea level ), a view of the upper part of the glacier was made possible for people who are not used to the mountains.
On the rocky slope of Faulberg east of Konkordiaplatz stand at 2850 m above sea level. M. the Konkordia huts of the Swiss Alpine Club SAC. They serve as an important stage on the high alpine glacier route from the Jungfraujoch or from the Lötschental to the Grimsel Pass area .
UNESCO World Natural Heritage
The area of the Great Aletsch Glacier, together with the unique Aletsch Forest and the surrounding regions, has been part of the Swiss Alps Jungfrau-Aletsch UNESCO World Heritage Site since December 13, 2001 .
See also
swell
- ↑ a b c Expert Commission for Cryosphere Measurement Networks (EKK) of the Swiss Academy of Sciences (SCNAT): The Swiss Glaciers 2005/2006 and 2006/2007. Glaciological Report No. 127/128. 2011 ( online ; PDF; 5.5 MB)
- ↑ a b Foundation UNESCO World Heritage Swiss Alps Jungfrau-Aletsch, Management Center: Ice Streams in the Aletsch Region. (PDF) 2011, accessed April 12, 2018 .
- ^ Research institute for hydraulic engineering, hydrology and glaciology (VAW) of the ETH Zurich : Aletsch Glacier. In: Glacier Natural Hazards. ( ethz.ch ( page no longer available ), also as a PDF ( page no longer available )).
- ^ Bonnard, Klee: Climate ecology and climate change on the Aletsch and Rhone glaciers in Wallis / southern Switzerland. , Johannes Gutenberg University Mainz, Institute of Geography, 2006 ( online ; PDF; 1.7 MB)
- ^ Editing of the Swiss Lexicon, Glacier Commission of the Swiss Academy of Natural Sciences (ed.): Glaciers, snow and ice. Page 7f, Verlag Schweizer Lexikon Mengis + Ziehr, Horw / Luzern 1993, ISBN 3-9520144-2-7
- ↑ P. Holzhauser (1995): Glacier fluctuations within the last 3200 years using the example of the Great Aletsch and Gorner Glaciers. In: Swiss Glacier Commission (ed.): Glaciers in constant change.
- ↑ Alpine glaciers have lost a sixth of their ice volume - derStandard.de. Retrieved June 26, 2020 (Austrian German).
Web links
- Aletsch Glacier on the ETHorama platform
- Research Institute for Hydraulic Engineering, Hydrology and Glaciology (VAW) of the ETH Zurich (Ed.): Measurements of the change in length of the Great Aletsch Glacier since 1870. In: Schweizerisches Gletschermessnetz. ( ethz.ch , also as PDF ).
- Arthur Fibicher: Aletsch Glacier. In: Historical Lexicon of Switzerland .
- Great Aletsch Glacier on Glaciers online
- Aletsch Glacier (PDF; 27 kB)
- UNESCO World Heritage Swiss Alps Jungfrau-Aletsch
- Hiking in the world heritage
- ETH Zurich: Changes in the size of the Aletsch Glacier
- The big Aletsch glacier in fast motion
- Interactive before and after comparison photos of the Aletsch Glacier
- Long-term Aletsch Glacier photo project