The saying goes, "a watched pot never boils." But don't say that to the thousands of visitors to Yellowstone National Park who come to watch the huge geysers erupt into the air.
Geysers are natural hot springs that occasionally eject boiling water and steam into the air. Geysers are actually very rare. In fact, there are fewer than 1000 geysers in the world today, and over half of those are located in Yellowstone.
The word "geyser" comes from a large geyser in Iceland named Geysir. In Danish, the name means gusher or spouter. The Icelandic people are so proud of their name that the word "Geysir" is copyrighted, so it cannot be used as the name of any other geyser.
Geysers are rare because they must have four conditions to exist: first, heat from volcanic magma very near the earth's surface; second, a supply of water that can circulate deep enough to be heated by the magma; third, cavities in the rocks just below ground level that can act as a pressure chamber; and fourth, special rocks that will provide enough silica to seal the pressure chamber and keep the pressure contained until an eruption results.
The most famous geyser is found in Yellowstone National Park. An eruption of Old Faithful lasts 90 seconds to five minutes, shoots out 37008400 gallons of boiling water, and reaches heights of 106184 feet.
Although its average interval has lengthened through the years to just over one hour, Old Faithful is still as spectacular as it was a century ago.
There are 120 named geysers in Yellowstone National Park. Among them are Steamboat, the world's tallest active geyser, which can erupt to more than 300 feet during its rare three-minute to forty-minute major eruptions; Minute, originally named for its eruptions every 60 seconds, which reaches heights of 40 to 50 feet; and Giant, whose eruptions reach up to 200 feet and last over one hour, at intervals of two days to three months.
While geysers are a spectacular site, remember that the next time you find yourself at Yellowstone National Park, hoping to see one up close, you may want to bring a book...you might be there a while.