Kerið
Encyclopedia
Kerið is a volcanic crater lake
Crater lake
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. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...

 located in the Grímsnes
Grímsnes
Grímsnes is a fissure or crater row volcano located in southwestern Iceland, a relatively small volcanic system located SE of Thingvallavatn lake east of an en echelon group of volcanic fields extending across the Reykjanes Peninsula. The elevation at its apex is 214 meters...

 area in south Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...

, on the popular tourist route known as the Golden Circle
Golden Circle (Iceland)
The Golden Circle is a popular tourist route in South Iceland, covering about 300 km looping from Reykjavík into central Iceland and back.The three primary stops on the route are the national park Þingvellir, the waterfall Gullfoss , and the geothermally active valley of Haukadalur, which contains...

. It is one of several crater lakes in the area, known as Iceland's Western Volcanic Zone, which includes the Reykjanes peninsula
Reykjanes
Reykjanes or Reykjanesskagi is a peninsula and a volcanic system situated at the south-western end of Iceland, near the capital of Reykjavík....

 and the Langjökull Glacier
Langjökull
Langjökull is the second largest ice cap in Iceland , after Vatnajökull. It is situated in the west of the Icelandic interior or Highlands of Iceland and can be seen clearly from Haukadalur....

, created as the land moved over a localized hotspot
Hotspot (geology)
The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them...

, but it is the one that has the most visually recognizable caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...

 still intact. The caldera, like the other volcanic rock
Volcanic rock
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it is an igneous rock of volcanic origin...

 in the area, is composed of a red (rather than black) volcanic rock. The caldera itself is approximately 55 m (180.4 ft) deep, 170 m (557.7 ft) wide, and 270 m (885.8 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
Aquamarine (color)
Aquamarine is a color that is a pale bright tint of spring green toned toward cyan. It is named after the mineral aquamarine, a gemstone mainly found in granite rocks...

.

Formation

Although volcanologists
Volcanology
Volcanology is the study of volcanoes, lava, magma, and related geological, geophysical and geochemical phenomena. The term volcanology is derived from the Latin word vulcan. Vulcan was the ancient Roman god of fire....

 originally believed Kerið was formed by a huge volcanic explosion, as is the accepted norm with volcanic craters, more thorough studies of the Grímsnes region failed to find any evidence of such an explosion in Kerið. It is now believed that Kerið was a cone volcano
Cinder cone
According to the , Cinder Cone is the proper name of 1 cinder cone in Canada and 7 cinder cones in the United States:In Canada: Cinder Cone In the United States:...

 which erupted and emptied its magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...

 reserve. Once the magma was depleted, the weight of the cone collapsed into the empty magma chamber. The current pool of water at the bottom of the crater is at the same level as the water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...

and is not caused by rainfall.
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