These are the outwash plains for the Icelandic volcano, Katla:
An outwash plain (or sandur) is a broad, shallowly sloping region ahead of a glacial front. They are made up of material that has been deposited by glacial meltwater, released either by geothermal heating or a subglacial eruption. The extensive volcanism and abundance of ice-capped volcanoes in southern Iceland means that the outwash plains are particularly well developed here.Outwash plains experience large-scale flooding events known as jökulhlaup (the singular is jökulhlaups, and comes from the Icelandic for ‘glacier flood’). Jökulhlaup present a significant hazard because huge volumes of sediment-laden water are released per second (104-106 m3) as erupting lava or geothermal heating causes rapid glacier melt from below. This footage of the jökulhlaups produced during the 2010 Icelandic eruptions – think back to the widespread flight disruption as ash from Eyjafjallajökull spread over Europe – gives you an idea of the scale and destructive power of these phenomena.
Between flooding events, some vegetation takes hold, but much of the soil is loose and easily transported by wind. Indeed, the soil islands you see in the photo are formed by wind-blown soil and if they were to erode, the area would be a desert consisting of glacial alluvial sediments alone. Sandstorms, such as the one above, carry fine particulate matter (clays and glacial till) from the outwash plains to other areas and even contribute to the particulate pollution in Reykjavík, some 110 km away!
Jóhannesdóttir, G. and Gísladóttir, G.: People living under threat of volcanic hazard in southern Iceland: vulnerability and risk perception, Natural Hazards Earth System Science, 10, 407-420, doi:10.5194/nhess-10-407-2010, 2010.
Thorsteinsson, T., Gísladóttir, G., Bullard, J. and McTainsh, G.: Dust storm contributions to airbourne particulate matter in Reykjavík, Iceland, Atmospheric Environment, 45, 5924-5933.
Warner, N.H.: Catastrophic outwash plains on Earth and Mars: comparisons from Iceland and Chasma Boreale, Mars. PhD thesis, Arisona State University, December, 2008.
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