geyser

—geyseral, geyseric, adj.

/guy"zeuhr, -seuhr/ for 1, 3; /gee"zeuhr/ for 2, n.

1. a hot spring that intermittently sends up fountainlike jets of water and steam into the air.

2. Brit. Informal. a hot-water heater, as for a bath.

v.i.

3. to spew forth as or like a geyser: the kettle geysering all over the stove.

[1755-65; < Icel Geysir name of a hot spring in Iceland, lit., gusher, deriv. of geysa to gush]

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(Icelandic geysir, "to rush forth") Any hot spring that discharges jets of steam and water intermittently, generally associated with recent volcanic activity and produced by the heating of underground waters that have come into contact with, or are very close to, magma.

Geyser discharges as high as 1,600 ft (500 m) have been recorded, but 160 ft (50 m) is much more common (e.g., Old Faithful in Yellowstone National Park). Occasionally, a geyser will adopt an extremely regular and predictable pattern of intermittent activity and discharge for a few minutes every hour or so.

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▪ geology

  hot spring that intermittently spouts jets of steam and hot water. The term is derived from the Icelandic word geysir, meaning “to gush.”

 Geysers result from the heating of groundwater by shallow bodies of magma. They are generally associated with areas that have seen past volcanic (volcano) activity. The spouting action is caused by the sudden release of pressure that has been confining near-boiling water in deep, narrow conduits beneath a geyser. As steam or gas bubbles begin to form in the conduit, hot water spills from the vent of the geyser, and the pressure is lowered on the water column below. Water at depth then exceeds its boiling point and flashes into steam, forcing more water from the conduit and lowering the pressure further. This chain reaction continues until the geyser exhausts its supply of boiling water.

      The boiling temperature of water increases with pressure; for example, at a depth of 30 metres (about 100 feet) below the surface, the boiling point is 140 °C (285 °F). Geothermal power from steam wells depends on the same volcanic heat sources and boiling temperature changes with depth that drive geyser displays.

 As water is ejected from geysers and cooled, dissolved silica is precipitated in mounds on the surface. This material is known as sinter. Often geysers have been given fanciful names (such as Castle Geyser) inspired by the shapes of the colourful and contorted mounds of siliceous sinter at the vents.

      Geysers are rare. There are about 500 of them in Yellowstone National Park in the western United States, about 200 on the Kamchatka Peninsula in Russia, about 40 in New Zealand, 16 in Iceland, and another 50 scattered throughout the world in many other volcanic areas. Perhaps the most famous geyser is Old Faithful in Yellowstone National Park. It spouts a column of boiling water and steam to a height of about 30 to 55 metres (100 to 180 feet) on a roughly 90-minute timetable.

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