Outwash plain

An outwash plain, also called a sandur (plural: sandurs), sandr or sandar, is a plain formed of glacial sediments deposited by meltwater outwash at the terminus of a glacier. As it flows, the glacier grinds the underlying rock surface and carries the debris along. The meltwater at the snout of the glacier deposits its load of sediment over the outwash plain, with larger boulders being deposited near the terminal morraine, and smaller particles travelling further before being deposited. Sandurs are common in Iceland where geothermal activity accelerates the melting of ice flows and the deposition of sediment by meltwater. Sandurs derive their name from Skeiðarársandur in Iceland, the largest outwash plain in the world with an area of 1,300 km² (500 sq mi).

Formation

Sandurs are found in glaciated areas, such as Svalbard, Kerguelen Islands, and Iceland. Glaciers and icecaps contain large amounts of silt and sediment, picked up as they erode the underlying rocks when they move slowly downhill, and at the snout of the glacier, meltwater can carry this sediment away from the glacier and deposit it on a broad plain. The material in the outwash plain is often size-sorted by the water runoff of the melting glacier with the finest materials, like silt, being the most distantly re-deposited, whereas larger boulders are the closest to the original terminus of the glacier.

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International System of Units

The International System of Units (French: Système international d'unités, SI) is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units. It defines twenty-two named units, and includes many more unnamed coherent derived units. The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units.

The system was published in 1960 as the result of an initiative that started in 1948. It is based on the metre-kilogram-second system of units (MKS) rather than any variant of the centimetre-gram-second system (CGS). SI is intended to be an evolving system, so prefixes and units are created and unit definitions are modified through international agreement as the technology of measurement progresses and the precision of measurements improves. The 24th and 25th General Conferences on Weights and Measures (CGPM) in 2011 and 2014, for example, discussed a proposal to change the definition of the kilogram, linking it to an invariant of nature rather than to the mass of a material artefact, thereby ensuring long-term stability.

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Exit Glacier

Exit Glacier is a glacier derived from the Harding Icefield in the Kenai Mountains of Alaska and one of Kenai Fjords National Park's major attractions. It is one of the most accessible valley glaciers in Alaska and is a visible indicator of glacial recession due to anthropogenic climate change. Exit Glacier retreated approximately 187 feet from 2013 to 2014 and park scientists continue to monitor and record the glacier's accelerating recession.

It received its name because it served as the exit for the first recorded crossing of the Harding Icefield in 1968.

History

In the spring of 1968, the first documented mountaineering party succeeded in crossing the Harding Icefield. Ten people were involved in the crossing, which went from Chernof Glacier east to Resurrection Glacier (Later renamed Exit as the newspaper reported that the group would be descending the "Exit Glacier"). Expedition members included Bill Babcock, Eric Barnes, Bill Fox, Dave Johnston, Yule Kilcher and his son Otto, Dave Spencer, Helmut Tschaffert, and Vin and Grace (Jansen) Hoeman. As noted above, Yule Kilcher, Dave Johnston, Vin Hoeman, and Grace Hoeman were veterans of previous attempts; of the ten, only four–Bill Babcock, Dave Johnston, Yule Kilcher, and Vin Hoeman–hiked all the way across the icefield. The expedition left Homer on April 17, bound for Chernof Glacier; eight days later, they descended Exit Glacier and arrived in Seward. Along the way, the party made a first-ever ascent of Truuli Peak, a 6,612-foot (2,015 m) eminence that protrudes from the northwestern edge of the icefield near Truuli Glacier.