Ground Water Features

Groundwater Features : Geysers of Yellowstone National Park

The groundwater feature that is analyzed in this essay is the geysers of Yellowstone National Park . The Yellowstone National Park is located primarily in the state of Wyoming , with some small areas in neighboring states of Idaho and Montana in the United States of America

A geyser is a type of hot spring that erupts periodically , discharging a column hot water and steam up into the air . Geysers are found only in regions of volcanic activity and are connected to masses of siliceous lava . Geysers

usually have a narrow vent at the surface that is connected to the groundwater chamber through one or more narrow tubes which form the plumbing of the geysers . The groundwater gets heated up by underlying rocks that in turn get conducted heat from the magma . This geothermally heated water gets constricted by the non-porous inner walls of a geyser and is trapped under layers of cooler water blocking the vents . The high pressure prevents ebullition and superheated temperatures are reached . Gradually , the upper layers that are not under pressure get hot enough for boiling . The steam pushes through the vents displacing the topmost layers of water and thereby releasing the pressure on the lower superheated layers . The superheated water then gushes out and a part of it gets converted into steam . This causes the violent eruption of a geyser . Once this eruption is over , the residual water cools down below boiling point , the heated groundwater seeps back into the reservoir and the cycle begins again (Hobbs ,1931

Yellowstone contains more than 300 geysers , about two thirds of the volcanic activity of Yellowstone Caldera , the largest volcanic system in entire North America . The current Caldera was formed 640 ,000 years ago by a massive eruption that released more than a thousand cubic Km of rock , ash and pyroclastic materials . This was followed by a couple of smaller eruptive cycles , the last one ending 70 , 000 years ago . The caldera was nearly filled with rhyolitic and basaltic lava flows due to these eruptions . The rhyolitic flow was very viscous and the rhyolite silica rich , acidic and water soluble in nature . Parts of this rhyolitic deposits got dissolved in hot water to form siliceous sinter or geyserite deposits on the inside walls of the geyser plumbing . With time , these deposits accumulated , strengthening the plumbing walls and providing stability to the geyser . At Yellowstone , the magma lies only 6 Km below the surface . The groundwater attains temperatures of 200o C at depths of 200m . These are ideal conditions for geyser activities . Each geyser here has developed its own typical pattern of duration , height and interval of eruption depending upon its water supply , fissures and internal structure (Scarth , 1994 . Yellowstone abounds in both cone geysers like the Old Faithful , where the jet of water erupts out of a small vent in a geyserite mound and fountain geysers like the Cistern Spring , that erupts violently from a pool with a relatively larger vent .The...