Geysers and Hot Springs
Geysers are hot springs that erupt periodically and eject water turbulently into the air. This discharge phase is followed by another phase where vapor (steam) is also released into the air. The word geyser comes from Geyser, the name of an erupting spring at Haukadalur, Iceland; that name, in turn, comes from the Icelandic verb gjósa, which means, "to gush."
Geysers are formed as a result of very specific hydro geological conditions which can only be found in a very few places on Earth. The effect created by geysers is usually the result of its proximity to magma, or molten rock that exists beneath the earth’s surface. Generally, surface water works its way down to depth of around 7,000 feet where it meets up with the hot molten rocks. The boiling of the pressurized water that ensues, results in the geyser effect of hot water and steam spraying out of the geyser's surface vent.
There are two types of geysers - fountain geysers (which shoot water out in various directions through a pool) and cone geysers (which shoot water out in a fairly narrow jet, usually from a cone-like formation).
Yellowstone’s Colorful Hot Springs
Hot springs are similar to geysers, but their underground channels are large enough to allow for rapid water circulation. Water, which has been heated underground and has risen to the surface, releases heat energy through evaporation or hot water runoff, while convection currents return the cooler water to the underground system, thus maintaining equilibrium.
Many of the bright colors found in Yellowstone’s hydrothermal basins come from “thermophiles,” or microorganisms which thrive in hot temperatures, and which live in and around the hot springs. When huge numbers (trillions!) Of individual microorganisms group together, they appear as masses of color.
Different types of thermophiles live at different temperatures within a hot spring, and cannot tolerate much cooler or warmer conditions. Yellowstone’s hot water systems often show distinct gradations of living, vibrant colors where the temperature limit of one group of microbes is reached, only to be replaced by a different set of thermophiles.
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