Geyser is a hot spring, which erupts intermittently in a column of steam
and hot water. Some geysers erupt at regular intervals, but most erupt
irregularly, the intervals ranging from a matter of minutes to years.
The length of time of the eruption varies with the geyser, from seconds
to hours. The height of the column ranges from about 1 m (3 ft) to about
100 m (328 ft), and the amount of water ejected in a single eruption
varies from a few litres to hundreds of thousands of litres.
A geyser erupts when the base of a column of water resting
in the earth is vaporized by hot volcanic rock. The force
with which the water column is expelled depends on its
depth. The weight of the water column increases with its depth. The
weight, in turn, increases the pressure exerted on the base
of the column, thereby increasing the boiling point of the
water there. When the water finally boils, it expands,
driving some water out into the air. With the weight of the
column reduced, the pressure correspondingly drops, and the
boiling point of the water remaining in the column falls below its actual temperature. Thereupon, the
entire column instantly vaporizes, causing the geyser to
all known geysers are located in three countries of the world—New
Zealand, Iceland, and the United States. The most famous geyser in the
world is Old Faithful in Yellowstone National Park in the United States,
which expels about 38,000 to 45,000 litres (10,000 to 12,000 gallons) at
each eruption. Old Faithful erupts at intervals of between 37 and 93
minutes, its column rising to a height of between 38 and 52 m (125 and
170 ft). The geyser gives warning of its impending activity by ejecting
jets of water 3 to 7.6 m (10 to 25 ft) high.
intervals depend on such variables as the atmospheric pressure, the supply of heat, the amount and
rate of inflow of subsurface water, and the nature of the geyser tube
and its underground connections.