what is a geyser

A geyser is a rare kind of hot spring that is under pressure and erupts, sending jets of water and steam into the air. Geysers are nonpermanent geological features and are generally associated with volcanic areas. They are formed by particular hydrogeological conditions that exist only in a few places on Earth. The formation of geysers requires the combination of three geologic conditions that are usually found in volcanic terrain: intense heat, water, and a plumbing system. There are two types of geysers: fountain geysers which erupt from pools of water, typically in a series of intense, even violent, bursts; and cone geysers which erupt from cones or mounds of siliceous sinter (including geyserite), usually in steady jets that last anywhere from a few seconds to several minutes. The eruption of a geyser is powered by a "steam explosion" when boiling-hot water suddenly expands into the much more voluminous steam. The constriction that holds in the mounting pressure creates a geysers plumbing system. Hot springs have unconstricted plumbing systems.