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|Yellowstone National Park (2)|
Upper Geyser Basin
Without question Yellowstone's most famous items are the over 10,000 hydrothermal features found throughout the park. These features are the result of the "Yellowstone Hot Spot"--a section where the thickness of the earth's crust is extremely thin. The magma below the crust is less than two miles below the surface in this area while it is typically more like 20-30 miles deep; the planet's internal heat is closer to the surface here than anywhere else on earth. Water from heavy precipitation in the area--primarily rain and snow--seeps down through the porous rock which comprises the ground until it is superheated, begins to rise, and eventually returns to the earth as a geyser, hot spring, pool, mud pot, or other hydrothermal feature. This trip from surface back to surface may take 500 years.
The most famous of the hydrothermal features at Yellowstone is the geyser. A geyser is basically a hot spring from which hot water and steam are ejected on a regular or irregular basis. Geysers occur when a combination of heat, water, and the appropriate underground plumbing exist together.
Yellowstone has the greatest concentration of geysers in the world. There are approximately 200 of these features in the park. The Upper Geyser Basin itself is surrounded by low cliffs of rhyolite.
There are two main types of geysers eruptions. There are cone-type geysers, in which the eruption emanates from geyserite cone at the ground surface. These eruptions are quite forceful. Alternately, there are fountain-type geysers with open craters filled with water.
Different geysers erupt at different schedules, some frequently and some at long intervals. Further, old geysers may eventually cease to erupt and new geysers may take their place.
With hot springs water and steam are discharged steadily. The park features two types of hot springs, one in which the water flows and creates terraces, such as at Mammoth Hot Springs, or others in which the springs are manifested as pools.
The various colors seen in the hot springs and pool are the result of a number of different factors. Sulfur is the cause of the yellow colors. Red colors result from iron oxides. Bacteria are responsible for pink hues, and other colors are typically the result of the growth of algae.
Of all the geyser basins in the park the most remarkable is probably the Upper Geyser Basin. This is due not only to the fact that it contains the world's most famous geyser, Old Faithful, but also because of its proximity to Old Faithful Inn and a variety of visitor amenities. This basin stretches for about 2 miles along the Firehole River in the west central portion of the park.
The Upper Geyser Basin contains the world's greatest concentration of hot springs and geysers. About one mile long, it contains 130 active geysers, which represents, remarkably, 1/4 of the total of all the geysers in the world, and more than 600 other hot springs and steam vents. Other places in the world in which geysers can be found include Iceland, New Zealand, Chile, and the Kamchatka Peninsula in Russia.
The Upper Geyser Basin is one of the collections of hydrothermal features which are located on the banks of the Firehole River, and is in fact the most upstream of those basins. It was discovered in 1833 by a group of men led by Manuel Alarez. The area is also well known for an abundance of wildlife.
The Upper Geyser Basin is a heavily visited area of the park. Not only does it contain Old Faithful and many other hydrothermal features, but there are a number of visitor amenities. A visitor center, restaurant, and also the famous Old Faithful Inn are located close to Old Faithful itself, and boardwalks allow visitors to safely explore the hydrothermal features.
Anemone Geyser can easily be viewed from the Upper Geyser Basin boardwalk. The geyser erupts up to 2 minutes every 3-8 minutes, to a height of about 3 to 10 feet.
Some geysers have cones which forma around their openings and are composed of geyserite, a hard rock-like material. One such feature is Beehive Geyser, shown below, which has a cone 3 1/2 feet high and 4 feet in diameter, which the 1870 Washburne Expedition thought resembled a beehive and thus gave it its name. This geyser erupts for 4 or 5 minutes every 7 hours to a number of days, and may go dormant for weeks or months. It sends water 150 to 200 feet into the air
There is a relationship between earthquakes and various hydrothermal features, which may be altered when they occur. Some 30 tremor can be felt each year. A large, 7.1 magnitude earthquake occurred on August 17, 1959, causing chimneys on the Old Faithful Inn to buckle. Following this event, some 290 geysers in the park were observed to erupt.
Before 1859 Depression Geyser (below) rarely erupted and in fact had no name. The 1959 earthquake stimulated its activity.
The Lion Geyser Group is made up of 4 separate geysers-the Lion, Lioness, Big, and Little Cub Geysers. The main geyser was named in 1881 by Colonel P. W. Norris for its resemblance to a reclining lion.
To hot springs combine to form Doublet Pool, below. The pools is 8 by 25 feet and is 8 feet deep, and is sapphire blue in color.
Sadly, vandalism of geothermal features has been a problem, and was particularly serious in the early days of tourism in the park area. Throwing things into hot springs, for example, may seal off the feature, or in other cases might stimulate an eruption.
Chinese Spring is a hot spring 28 by 34 inches and 12.5 feet deep. Basically a hot spring, it has erupted but only when induced to do so. Its name is derived from the Chinese laundryman who unintentionally induced the first known eruption in the process of using the spring to do laundry.
The end of the day does not end the sights presented by the hydrothermal features in the basin.
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