Miage Glacier
Encyclopedia
The Miage Glacier is a debris
-covered glacier
in northwestern Italy
. It is situated on the southwest flank of the Mont Blanc massif
, flowing from Col de Bionnassay (3892 m (12,769 ft) above sea level) into Val Veny
. At around 10 km (6.2 mi) in length, it is Italy's longest glacier and also the largest debris-covered glacier in Europe. Approximately 5 km² (1.9 sq mi) of its total area of ~11 km² (4.2 sq mi) is covered in debris originating primarily in rockfall
from surrounding walls and avalanching in accumulation areas of its four tributaries. 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
of the rock walls surrounding the glacier, makes for a varied debris lithology; debris cover becomes continuous at ~2400 m (7,874 ft) 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 2400 m (7,874 ft) asl to over 1 metres (3.3 ft) at the terminus at ~1775 m (5,823.5 ft) asl, although the spatial distribution of thicknesses is heterogeneous especially on parts of the northern terminal lobe.
due to the spectacular ice cliffs rising up to one side and its two-coloured appearance. The colours reflect varying sediment
concentrations in the water which arise as a result of the filtering
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.
Debris
Debris is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, in geology, large rock fragments left by a melting glacier etc. The singular form of debris is debris...
-covered glacier
Glacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
in northwestern Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
. It is situated on the southwest flank of the Mont Blanc massif
Mont Blanc Massif
The Mont Blanc massif is a mountain range in the western Alps. It is named after Mont Blanc, at 4,810.45 m the highest summit of the Alps. It is located in France , Italy , and Switzerland...
, flowing from Col de Bionnassay (3892 m (12,769 ft) above sea level) into Val Veny
Val Veny
Val Veny is a lateral valley of the Mont Blanc massif, lying to the south-west of Courmayeur. The valley head is at the col de la Seigne, over which lies the Tarentaise Valley.- Geography:...
. At around 10 km (6.2 mi) in length, it is Italy's longest glacier and also the largest debris-covered glacier in Europe. Approximately 5 km² (1.9 sq mi) of its total area of ~11 km² (4.2 sq mi) is covered in debris originating primarily in rockfall
Rockfall
Rockfall or rock-fall refers to quantities of rock falling freely from a cliff face. A rockfall is a fragment of rock detached by sliding, toppling, or falling, that falls along a vertical or sub-vertical cliff, proceeds down slope by bouncing and flying along ballistic trajectories or by rolling...
from surrounding walls and avalanching in accumulation areas of its four tributaries. 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
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, such as colour, texture, grain size, or composition. It may be either a detailed description of these characteristics or be a summary of...
of the rock walls surrounding the glacier, makes for a varied debris lithology; debris cover becomes continuous at ~2400 m (7,874 ft) above mean sea level (asl) and remains unbroken to the terminus
Glacier terminus
A glacier terminus, or snout, is the end of a glacier at any given point in time. Although glaciers seem motionless to the observer, in reality glaciers are in endless motion and the glacier terminus is always either advancing or retreating...
. Patchy areas can occur, however, where crevasses or moulins
Moulin (geology)
A moulin or glacier mill is a roughly circular, vertical to nearly vertical well-like shaft within the a glacier through which water enters it from the surface. The term is derived from the French word for mill....
occur. Debris thickness generally increases from a few centimetres at 2400 m (7,874 ft) asl to over 1 metres (3.3 ft) at the terminus at ~1775 m (5,823.5 ft) 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 attractionTourist attraction
A tourist attraction is a place of interest where tourists visit, typically for its inherent or exhibited cultural value, historical significance, natural or built beauty, or amusement opportunities....
due to the spectacular ice cliffs rising up to one side and its two-coloured appearance. The colours reflect varying sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
concentrations in the water which arise as a result of the filtering
Filter (chemistry)
In chemistry and common usage, a filter is a device that is designed to physically block certain objects or substances while letting others through. Filters are often used to remove solid substances suspended in fluids, for example to remove air pollution, to make water drinkable, and to prepare...
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.