Strokkur

Ever since medieval times,Iceland has been famous for its many hot springs and geysers. Although the Geysir's performance has become less impressive in recent times, dozens of other hot springs continue to bubble and spurt in the same thermal area in southwestern Iceland. Amoung the most active and predictable in the group, located in a valley at the foot of a rangeof volcanic mountains, is Strokkur, the "churn". Every 4 to 10 minutes it shoots a jet of boiling water as high as 100 feet into the sky.

Fluctuations in the water level in its basin herald each eruption. As the turbulence increases, the surface of the water heaves up into a dome, then explodes into a cloumn of steam and water droplets. The clouds of vapour blow away on the breeze, but the water falls back to the basin to contribute to the next eruption. The abundance of geysers is due to Iceland's geological history. In this volcanically active zone, molten magama lies close to the earth's surface, where it heats underground water and powers its periodic eruptive escapes through fissures in the crust.