- published: 25 Aug 2011
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Kerið (occasionally Anglicized as Kerith or Kerid) is a volcanic crater lake located in the Grímsnes area in south Iceland, on the popular tourist route known as the Golden Circle. It is one of several crater lakes in the area, known as Iceland's Western Volcanic Zone, which includes the Reykjanes peninsula and the Langjökull Glacier, created as the land moved over a localized hotspot, but it is the one that has the most visually recognizable caldera still intact. The caldera, like the other volcanic rock in the area, is composed of a red (rather than black) volcanic rock. The caldera itself is approximately 55 m (180 ft) deep, 170 m (560 ft) wide, and 270 m (890 ft) across. Kerið’s caldera is one of the three most recognizable volcanic craters because at approximately 3,000 years old, it is only half the age of most of the surrounding volcanic features. The other two are Seyðishólar and Kerhóll.
While most of the crater is steep-walled with little vegetation, one wall is sloped more gently and blanketed with a deep moss, and can be descended fairly easily. The lake itself is fairly shallow (7–14 metres, depending on rainfall and other factors), but due to minerals from the soil, is an opaque and strikingly vivid aquamarine.
A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite, or in an artificial explosion caused by humans. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not made. Crater lakes covering active (fumarolic) volcanic vents are sometimes known as volcanic lakes, and the water within them is often acidic, saturated with volcanic gases, and cloudy with a strong greenish color. Lakes located in dormant or extinct volcanoes tend to have fresh water, and the water clarity in such lakes can be exceptional due to the lack of inflowing streams and sediment.
Lava lakes, a rare phenomenon where a volcanic crater can sustainably contain a significant volume of molten lava, are discussed in a separate article.
Crater lakes form as precipitation within the rim fills the created depression. The water level rises until an equilibrium is reached between the rate of incoming and outgoing water. Sources of water loss singly or together, may include evaporation, subsurface seepage, and in places, surface leakage or overflow when the lake level reaches the lowest point on its rim. At such a saddle location, the upper portion of the lake is contained only by its adjacent natural volcanic dam; continued leakage through or surface outflow across the dam can erode its included material, thus lowering lake level until a new equilibrium of water flow, erosion and rock resistance is established. If the volcanic dam portion erodes rapidly or fails catastrophically, the occurrence produces a breakout or outburst flood. With changes in environmental conditions over time, the occurrence of such floods is common to all natural dam types.