Geysers are hot springs that episodically erupt fountains of scalding water and steam. Such eruptions occur as a consequence of groundwater being heated to its boiling temperature in a confined space (for example, a fracture or conduit). A slight decrease in pressure or an increase in temperature will cause some of the water to boil. The resulting steam forces overlying water up through the conduit and onto the ground. This loss of water further reduces pressure within the conduit system, and most of the remaining water suddenly converts to steam and erupts at the surface.
The most significant area for geysers in the United States of America is Yellowstone National Park, with the best known being Old Faithful.
- Geyser Observation and Study Associaton (GOSA) GOSA's purpose is the collection and dissemination of information about geysers and other geothermal phenomena in Yellowstone National Park and elsewhere.
- How do Geysers Work?, Videos © 2007 Yellowstone Association
- How Do You Tell a Geyser from a Hot Spring?, Videos © 2007 Yellowstone Association