By Martin Kerstein
N 64° 18.746′ W 020° 18.042′
Iceland has set itself apart as a highly sought-after destination for EarthCache connoisseurs. One might say the overall beauty of the island, with its many geological marvels, makes it one big EarthCache. The most favorited EarthCache in Iceland makes for a spectacular sight, being an explosive choice for Geocache of the Week.
Geysir – powerful hot spring, also known as The Great Geysir, has been active for approximately 10,000 years. The English term geyser derives from the old Norse verb geysa, which means “to gush.”
Geysers erupt because the thermal water ascending through their channels boils at some depth below the surface. It is a breathtaking sight and the geological science behind it is fascinating.
At about 23 m (75 ft) depth in Geysir’s infrastructure, the water is at 120°C (240°F) temperature and is in equilibrium with the pressure of the water above in the pipe, i.e. the weight of the water above counteracts the boiling below. At a depth of around 16 m (52 ft), the temperature of the water sometimes rises above boiling, seen as an increased disturbance on the surface.
This turbulence can increase to the point where the water in the pipe above is elevated slightly, which sets off a chain reaction — the pressure decreases, which makes boiling possible further below the surface, flashing the water from the deepest recesses into a cloud of steam, pushing against the boiling water above it resulting in an eruption accompanied by a distinct noise.
The water phase lasts only for a few minutes, while the steam phase is active for a considerably longer period of time. As the steam phase ends, the geyser’s deep channels have been drained of all water and it will take eight to ten hours for Geysir to refill.
In recent years Geysir has been rather subdued, but the multiple smaller, more active geysers in the area make this a worthwhile visit to experience one of nature’s wonders.
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