Yellowstone National Park Old Faithful Geyser Basin

The Old Faithful area is perhaps the most popular attraction for visitors in Yellowstone National Park. The Old Faithful area, also known as the Upper Geyser Basin, has the world's highest concentrations of active geysers.

	The Old Faithful Geyser erupts more frequently than any of the other big geysers, although it is not the largest or most regular geyser in the park. Its average interval between eruptions is about 76 minutes, varying from 45 - 110 minutes. An eruption lasts 1 1/2 to 5 minutes, expels 3,700 - 8,400 gallons (14,000 - 32,000 liters) of boiling water, and reaches heights of 106 - 184 feet (30 - 55m). It was named for its consistent performance by members of the Washburn Expedition in 1870. Although its average interval has lengthened through the years (due to earthquakes and vandalism), Old Faithful is still as spectacular and predictable as it was a century ago.

	Infrequent but violent eruptions characterize Giantess Geyser. This fountain-type geyser erupts in several bursts 100 - 200 ft (30 - 60m) high. Eruptions generally occur 2 - 6 times a year. The surrounding area may shake from underground steam explosions just before the initial water and/or steam eruptions. Eruptions may occur twice hourly and continue for 12 - 43 hours.

	Beehive Geyser is magnificent. Eruptions usually occur twice each day with displays lasting 4 - 5 minutes. During an eruption, the narrow cone acts like a nozzle, projecting the water column to heights of 130 - 190 ft (40 - 55m).

	The Lion Group consists of four geysers: Lion, Lioness, Big Cub, and Little Cub, which are all connected underground. Of these Lion has the largest cone and eruptions. Active phases normally occur each day. Eruptions of Lion Geyser last 1 - 7 minutes and are often preceded by sudden gushes of steam and a deep roaring sound, hence the name Lion.

	Sawmill Geyser's eruptions are highly variable, some lasting only 9 minutes while others may last over 4 hours. The typical interval between eruptions is 1 - 3 hours. Overall it is erupting about 30% of the time. Sawmill received its name because water spins in its crater as it erupts looking somewhat like the rotating circular blade of a lumber mill.

	An eruption of Grand Geyser, the tallest predictable geyser in the world, occurs every 7 - 15 hours. A classic fountain geyser, Grand erupts from a large pool with powerful bursts rather than a steady column like Old Faithful. An average eruption lasts 9 - 12 minutes and consists of 1 - 4 bursts, sometimes reaching 200 feet (60m).

	Castle Geyser has the largest cone and may be the oldest of all geysers in the basin. Its eruption pattern has changed considerably throughout its recorded history. Castle is currently erupting about every 10 - 12 hours. A water eruption frequently reaches 90 feet (27m) and lasts about 20 minutes. The water phase is followed by a noisy steam phase lasting 30 - 40 minutes.

	Truly deserving its name, Beauty Pool is noted for its rich, blue water framed by rainbow-colored bacteria. It's plumbing system is closely related to the neighboring Chromatic Spring.

	Chromatic Spring is closely related to Beauty Pool. During periodic energy shifts the level of one spring descends while the other rises and overflows. The time interval between shifts has ranged from a few weeks to several years.

	Giant Geyser was dormant for many years after the energy shift in 1955. Since then, it has slowly become active again. During 1997, its eruptions occurred every 3 - 10 days. This spectacular geyser's eruptions last about an hour and can reach heights of 180 - 250 feet (55 - 76m). During eruptions small geysers nearby may also erupt.

	Comet Geyser is a member of the Daisy Group which also contains Daisy and Splendid Geysers. Comet has the largest cone of the three but has, by far, the smallest eruptions. The nearly constant splashing of Comet over a long period of time has resulted in its large cone. Eruptions rarely exceed 6 feet in height.

	Splendid Geyser's eruptions are at times over 200 feet in height, making it among the tallest geysers in Yellowstone. Its eruptions are infrequent and difficult to predict except for the fact that it is more likely to erupt when a storm front rapidly reduces the barometric pressure in the area. This slightly reduces the boiling temperature in the plumbing system and occasionally triggers a splendid eruption.

	Situated on the bank of the Firehole River, Riverside Geyser is one of the most picturesque geysers in the park. During its 20-minute eruptions, a 75 foot (23m) column of water arches gracefully over the river. Eruptions are about 5-1/2 to 6-1/2 hours apart. There is water runoff over the edge of Riverside's cone for an hour or two before each eruption. Many geysers have similar "indications" that they are about to erupt.

	Fan and Mortar Geysers are in close proximity to one another and almost always erupt in concert. The interval between eruptions ranges from 1-1/2 days to months. Most eruptions last about 45 minutes. Mortar Geyser, pictured here, erupts to heights of 40 - 80 feet while Fan can reach heights of 100 - 125 feet.

	Long a favored destination for park visitors, Morning Glory Pool was named in the 1880s for its remarkable likeness to its namesake flower. However, this beautiful pool has fallen victim to vandalism. People have thrown literally tons of coins, trash, rocks, and logs into the pool. Much of the debris subsequently became embedded in the sides and vent of the spring, affecting water circulation and accelerating the loss of thermal energy. Through the years Morning Glory's appearance has changed as its temperature dropped. Orange and yellow bacteria that formerly colored only the periphery of the spring now spread toward its center.

In conclusion, the Old Faithful area is likely the most popular attraction in Yellowstone National Park. With so much to see and so many park visitors, it is recommended that you plan to spend some extra time at Old Faithful. The area is a rare gem and is unique to Yellowstone - there is no other place like this on Earth!