The Miage Glacier (french: Glacier du Miage; it, Ghiacciaio del Miage) is a

debris Debris (, ) is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, as in geology, large rock fragments left by a melting glacier, etc. Depending on context, ''debris'' can refer to ...

-covered

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...

in the upper

Aosta Valley , Valdostan or Valdotainian it, Valdostano (man) it, Valdostana (woman)french: Valdôtain (man)french: Valdôtaine (woman) , population_note = , population_blank1_title = Official languages , population_blank1 = Italian French ...

, in northwestern

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

Description

It is situated on the southwest flank of the

Mont Blanc massif The Mont Blanc massif (french: Massif du Mont-Blanc; it, Massiccio del Monte Bianco) is a mountain range in the Alps, located mostly in France and Italy, but also straddling Switzerland at its northeastern end. It contains eleven major indepen ...

, flowing from the Col de Bionnassay (

above sea level Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as ''orthometric heights''. The comb ...

) in a generally southerly direction towards

Val Veny Val Veny (also Val Vény) is a lateral valley of the Mont Blanc massif, lying to the south-west of Courmayeur. The valley head is at the Seigne Pass. Geography Val Veny was formed by two glaciers: the Miage Glacier and the Brenva Glacier. V ...

. Its most northerly arm or tributary is the Glacier de Bionnassay Italien, which arises from a cirque between the south eastern side of the Aiguille de Bionnassay, the Col de Bionnassay and the Calotte des Aiguille Grises. This descends for 2.5 km below the Col Infranchissible then turns south-east to merge with other glaciers, thence continuing as the Glacier du Miage (Ghiacciaio del Miage). At around in length, the Miage Glacier is Italy's longest glacier and also the largest debris-covered glacier in Europe. Approximately of its total area of ~ is covered in debris originating primarily in

rockfall A rockfall or rock-fallWhittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984. . is a quantity/sheets of rock that has fallen freely from a cliff face. The term is also used for collapse of rock from roof or walls of min ...

from surrounding walls and avalanching in accumulation areas of its four

tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage b ...

. Debris carried along within the glacier is also being exposed at increased rates due to accelerating thinning of the glacier tongue. The number of sources of supraglacial debris as well as the unusual,

mica schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes ...

-dominated

lithology The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...

of the rock walls surrounding the glacier, makes for a varied debris lithology; debris cover becomes continuous at ~ above mean sea level (asl) and remains unbroken to the

terminus Terminus may refer to: * Bus terminus, a bus station serving as an end destination * Terminal train station or terminus, a railway station serving as an end destination Geography *Terminus, the unofficial original name of Atlanta, Georgia, United ...

. Patchy areas can occur, however, where

crevasses A crevasse is a deep crack, that forms in a glacier or ice sheet that can be a few inches across to over 40 feet. Crevasses form as a result of the movement and resulting stress associated with the shear stress generated when two semi-rigid pie ...

or moulins occur. Debris thickness generally increases from a few centimetres at asl to over at the terminus at ~ asl, although the spatial distribution of thicknesses is heterogeneous especially on parts of the northern terminal lobe.

Miage Lake

Miage Lake is an ice-contact lake near the southern end of the Miage Glacier, located on the outside of the glacier's 90-degree bend eastwards. It is a popular

tourist attraction A tourist attraction is a place of interest that tourists visit, typically for its inherent or an exhibited natural or cultural value, historical significance, natural or built beauty, offering leisure and amusement. Types Places of natural b ...

due to the spectacular

ice cliff Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opa ...

s rising up to one side and its two-coloured appearance. The colours reflect varying

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...

concentrations in the water which arise as a result of the

filtering Filter, filtering or filters may refer to: Science and technology Computing * Filter (higher-order function), in functional programming * Filter (software), a computer program to process a data stream * Filter (video), a software component tha ...

effect of the debris. Huge ice blocks have been known to break off the glacier and fall into the lake, providing another major tourist attraction despite the low chance of such an event occurring. On August 7, 1996, a particularly large block, estimated to have had a volume of 7000-16000m³, fell into the lake causing an abnormally large wave that seriously injured several people. The incident was caught on camera by at least one tourist.

References

{{Mont Blanc massif Glaciers of Italy Glaciers of the Alps