솔헤이마요쿨(Sólheimajökull) 안내. 아이슬란드(Iceland)

솔헤이마요쿨(Sólheimajökull) 안내. 아이슬란드(Iceland)

Sólheimajökull margin, 2004

The Geomorphology of Sólheimajökull Glacier

The erosional power of outlet glaciers is substantial and the sediment that is formed is referred as glacial sediment. The different sediment formation and landforms are named after how they are formed and how and where the glacier deposits the sediment.

Formations on the glacier

Moulins are formed when water starts to flow down through narrow cracks in the ice that widen constantly throughout the summer, as the water melts the ice walls. The circulr openings can becomes several metres in diameter and they are often very deep

Lateral moraines are formed along mountain slopes on the margins of the valley glaciers, below the equilibrium line. In some cases the lateral moraines combine, e.g. in front of nunataks, and therefore form medial moraines.

Dirt cones are alluvial cones, which can be seen in many places on glaciers. Sediment and ash collects in hollows on the glacier and manages to insulate the ice so it melts slower than the area surrounding it. When the ice surrounding it has reduced due to melting, picturesque cones are left behind.

Large rock marks the position of the 1995 ice front

Formations by the glacier margins

Moraines build up or are pushed up at the snout of the glacier from sediment that the glacier has carrried with it. How the moraines are formed varies depending on the behaviour of the glacier, either they are pushed up or they build up when the glacier margins deposit sediment.

Terminal moraines are the outermost moraine that the glacier forms and it shows how far the glacier has advanced during its growth period.

Recessional moraines are younger than the terminal moraine and they are closer to the glacier. They are formed during a temporary advance of the glacier, after the glacier has started retreating from the terminal moraine.

Annual moraines are formed by the slight advancement of the glacier in late winter, before the summer melt causes the recession of the snout of the glacier.

Sólheimasandur with megaripples formed during a major jökullhlaup

Formations in front of the glacier

Outwash plains (sandur) are plains formed of glacial sediments deposited by meltwater outwash at the terminus of a glacier. However the main flood deposits at this area are prehistoric and were formed by outburst floods (jökulhlaup) that accompanied Katla eruptions.

Jökulhlaup channels were formed during glacial outburst floods that came from the margin of Sólheimajökull glacier in 1999, probably due to a small eruption under the glacier. The outburst flood peaked at 1,700 ㎥/s and dug a 5-19 m deep sub-glacial gorge inside the 1999 ice margin

Kettle holes may be filled with water and represent areas of subsidence caused by the melt of buried ice. The ice can be either dead ice left by the glacier as the ice margin retreats, or icebergs carried onto outwash planes during glacial outburst floods.

Caution : This land is rapidly changing, Stones fall, ice bridge and ice caves collapse and quicksand is common near the glacier. Walk along the path and only go on the glacier with a professional guide.

Dirt cones on Sólheimajökull

Recessional moraine formed after 1995

Kettle hole in front of Sólheimajökull

Sólheimajökull glacier

Sólheimajökull glacier is an approximately 14 km long outlet glacier, which advances from Mýrdalsjökull glacier, down a one to two km wide valley. The glacier falls from a height of about 1,360 m down to 100 m and because of the location and shape of the glacier, it is sensitive to climate change. In the lowlands the climate is warm and humid with average temperatures above 5℃ and precipitation of 1,810 mm per year. Precipitation on Mýrdalsjökull glacier, however, is much higher, or up to 7,000 mm per year, and the average temperature is much lower.

At Sólheimajökull glacier, the glacier history of Iceland can be read out of the sediments and landforms. There can be found many prominent glacial moraines and sections that provide information on environmental history. Findings indicate that Sólheimajökull glacier significantly advanced approximately 1,900 years ago, and that lesser advancements occurred during the Little Ice Age, from 1539, when the glacial margins lay two kilometres further forward than they did in 2010.

Regular measurements have been made of the glacier snout since the 1930s. With the results of these measurements and aerial pictures, it can be seen that from 1930 to 1969, the glacier retreated in total around 977 m. Then the weather cooled and the glacier advanced forward about 495 m until 1995, and also thickened by up to 100 m. After that, the glacier started to retreat again and in 2010 it was almost one kilometre shorter than in 1930 and was 120 to 150 m thinner than in 1960. If the climate continues to warm, there is a possibility that the glaciers will have virtually disappeared in 100 to 200 years.

Outlet glaciers

Glaciers move downslope because the ice does not have strength to withstand its own weight. Icelandic glaciers also slide over their wet bed which is lubricated by water. There temperature is at the melting point (temperate). The advance rate is higher, the steeper the glacier and the more water enhances the sliding. The factors that decide whether the glacier terinus advances or retreats are connected to the accumulation and ablation on the glacier and are called the glacier mass balance. The glacier mass balance explains how the ice mass changes over time. If accumulation is more than ablation over the year, the glacier mass balance is said to be positive and the accumulation area grows, which causes the glacier to advance. The glacier remains as it is if there is equilibrium between ablation and accumulation, but retreats if the ablation is greater than accumulation. In winter, the spread of movement at the glacial margins is at a minimum because of the small amount of meltwater at its base. However, the speed is greater during the summer months due to the presence of more melt water. It unchanged or retreat, there is always movement due to internal deformation of the ice.

Sólheimajökull 1985

Sólheimajökull in 1997

Sólheimajökull in 2006

Sólheimajökull in 2010.

 

The glacier retreated about 500 m from 1997 to 2006 and the thinning of it was about 100 m.

In 2010 the glacier had retreated 300 metres more and thinned so much that the glacier can no more be seen from this position.

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