What is Geyser? Definition and Facts


What is a geyser? How do they form? Information, definition and facts about geysers.

Geyser; comes from the Icelandic word geysir which means “gusher” or “rager“. It is a hot spring which spouts hot water and steam into the air from time to time.

Geysers are found in many volcanic regions; for example, in Japan, in the area round Malaya and in South America. The three most famous regions, however, are Iceland, New Zealand’s North Island and the state of Wyoming in the United States. Different geysers have different habits. Some only throw up water a few feet, while others throw it up hundreds of feet; some a few gallons and others hundreds of thousands of gallons. Some gush much more often than others.


A geyser consists of a hole which goes deep I down into the earth to hot rock (which is probably uncooled lava) and of underground water. It erupts, or shoots hot water and steam into the air; when the water deep down in the hole reaches a temperature much above the normal boiling point. This water becomes so hot that it turns into steam, which lifts the water above, causing an overflow at the surface. Because some of the surface water has overflowed and relieved the pressure below, more of the deep water suddenly turns into steam, which expands and blows out with tremendous force, taking hot water with it.

Round the mouths of many geysers are mounds of mineral substances such as lime, for the hot water dissolves the earth’s minerals very easily and they are heaped wherever the water spreads and collects in pools. Tiny plants known as algae live in these warm pools and when they die their skeletons add to the mound of mineral substances. The minerals and plants give beautiful colours to the pools and wet rocks.

The Great Geyser of Iceland is in the middle of a mound of mineral substances 40 feet high. When it is calm it has a pool 60 feet across and feet deep. It erupts at intervals that vary from 6 to 30 hours, and it can throw up water to anything from 80 to 150 feet. Round it are other geysers, as well as hot springs that do not erupt.

The geyser district of New Zealand covers 5 000 square miles near Rotorua and Taupo in North Island. There are also a great many boiling springs and mud volcanoes. Because of the minerals dissolved in them some of the hot springs are used in the treatment of illnesses and many people bathe in their waters.

In Wyoming (United States) there are about 100 geysers and more than 3,000 hot springs. One geyser, called “Old Faithful”, erupts every hour and throws 100 feet of water into the air for about 5 minutes. The “Giantess” lifts the main column of water to only 60 feet but shoots a thin spire to no less than 250 feet. The “Castle” varies in height from 10 feet to 250 feet, when it also makes an enormous noise and shakes the earth like an earthquake.

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