Upper Geyser Basin
Tour the Old Faithful Visitor Center, consult the list of geyser eruption times predicted by the Yellowstone National Park Service, and buy one of The Yellowstone Association's inexpensive Old Faithful brochures, which includes a trail map and descriptions of individual geysers and springs. See Old Faithful, then take the Geyser Trail to begin a roughly 3 mile loop walk on the boardwalk across Geyser Hill, then past Giantess, Grand, Giant, Grotto, and Riverside geysers to Morning Glory Pool. Then return to Old Faithful by way of Daisy and Castle geysers. Shorter loops are available. Stay on the boardwalk to avoid damaging vegetation and brittle, delicate mineral deposits from the hot springs and geysers.
Geyser Hill purportedly contains one of the world's greatest concentrations of geysers. Giantess usually erupts only a few times a year, rising to heights greater than Old Faithful. Giantess' underground water supply is connected to other geysers on the hill. When it erupts, the other geysers erupt less frequently and less vigorously. Valt Geyser was dormant since 1988 until it was reactivated by a 1998 earthquake.
Old Faithful and Upper Geyser Basin are located in a flat area drained by the Firehole River. This flat area lies between two lava flows that did not quite converge. The geysers and hot springs in Upper Geyser Basin reach the surface because the land here was not covered by the lava flows. Water seeps into the ground from snow that blankets Yellowstone National Park each winter and then melts. Porous lava flows surrounding Upper Geyser Basin allow the water to percolate downward until it becomes superheated and eventually erupts through geysers or hot springs.
Geysers are eruptions of hot steam and water expelled from shallow chambers. When the pressure of the hot, undergound water becomes too great, water and steam erupt to the surface through narrow "pipes" in the geyser basin's subterranean plumbing system. It is similar to the pressure buildup within a pressure cooker. Geysers can erupt dozens to several hundred feet skyward. The hot water beneath Upper Geyser Basin reaches temperatures of more than 400 degrees Fahrenheit, well above boiling. The water cools to about 200 degrees Fahrenheit as it spurts from the geysers.
The time interval between eruptions of any geyser varies, along with the height and volume of water spewed from a geyser. Even Old Faithful is not what its name implies. It once erupted roughly hourly, but the intervals between outbursts became longer after the 1959 Hebgen Lake, Montana earthquake northwest of Yellowstone National Park and again after the 1983 Borah Peak earthquake in Idaho. After a small earthquake in early 1998, the average time between Old Faithful's eruptions increased a bit more, from about one every 76 minutes on average to about once every 80 minutes. Two geyser outbursts were 115 minutes apart. The 1998 quake temporarily reactivated some old geysers that had been quiet for years. Old Faithful expels water to an average height of 130 to 140 feet, but the range is between 98 and 183 feet.
Nearby and distant earthquakes change the timing and eruption height of geysers, probably by sealing or cracking open mineral deposits in a geyser basin's underground plumbing system, thus changing the flow of water into and out of the subterranean hot water reservoirs that feed geysers. Seismic waves also can stretch and compress the ground, charging underground water pressures to change the geyser plumbing system. In geologic time, any particular geyser is a temporary feature. Geysers can become dormant when they are sealed by mineral deposits or by garbage discarded by vandals. Earthquakes can change their plumbing and divert water away from them or create openings from which new geysers erupt.
Cone-shaped mineral deposits are found at geysers and hot springs throughout Upper Geyser Basin. The cones are made of geyserite, also called siliceous sinter, which is a silica-rich mineral that precipitates out of the hot water. As at West Thumb, the hot springs of Upper Geyser Basin are colored by various cyanobacteria. Biotechnology companies have been collecting these and other microbes from Yellowstone National Park's springs for industrial and scientific uses and there has been debate over whether the government is receiving adequate compensation from such companies.
network of Travel Guides