The Miage Glacier (; ) is a

debris Debris (, ) is rubble, wreckage, ruins, litter and discarded waste, 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 ref ...

-covered

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

in the upper

Aosta Valley The Aosta Valley ( ; ; ; or ), officially the Autonomous Region of Aosta Valley, is a mountainous Regions of Italy#Autonomous regions with special statute, autonomous region in northwestern Italy. It is bordered by Auvergne-Rhône-Alpes, Fr ...

, in northwestern

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

Description

It is situated on the southwest flank of the Mont Blanc massif, flowing from the Bionnassay Pass (

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

) in a generally southerly direction towards Val Veny. 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 Infranchissable'' then turns south-east to merge with other glaciers, thence continuing as the Miage glacier. 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 of Rock (geology), rock that has fallen freely from a cliff face. The term is also used for collapse of rock from roof or wa ...

from surrounding walls and avalanching in accumulation areas of its four

tributaries A tributary, or an ''affluent'', is a stream or river that flows into a larger stream ('' 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 into which the ...

. 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-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. Patchy areas can occur, however, where crevasses 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 exhibited natural or cultural value, historical significance, natural or built beauty, offering leisure and amusement. Types Places of natural beaut ...

due to the spectacular ice cliffs rising up to one side and its two-coloured appearance. The colours reflect varying

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

concentrations in the water which arise as a result of the

filtering Filtration is a physical process that separates solid matter and fluid from a mixture. Filter, filtering, filters or filtration may also refer to: Science and technology Computing * Filter (higher-order function), in functional programming * Fil ...

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 9, 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