Echinus Geyser is a geyser

Geyser

A geyser is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by a vapour phase . The word geyser comes from Geysir, the name of an erupting spring at Haukadalur, Iceland; that name, in turn, comes from the Icelandic verb geysa, "to gush", the verb...

 in the Norris Geyser Basin of Yellowstone National Park

Yellowstone National Park

Yellowstone National Park, established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872, is a national park located primarily in the U.S. state of Wyoming, although it also extends into Montana and Idaho...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

History

Echinus was named during one of the U.S. Geological Surveys of the park in the late 1870s or early 1880s. The name Echinus comes from the spiny appearance of the cone that resembles a Sea urchin

Sea urchin

Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...

 or class Echinoidea.

Eruption

Echinus' eruptions are unpredictable. Its fountain reaches a height of as much as 40 to 60 ft (12.2 to 18.3 ), with a duration of about 4 minutes. Prior to 1998, this geyser was very regular, every 35 to 75 minutes. There were also major eruptions that lasted as much as 118 minutes. It is speculated that there was a secondary underground water source that used to power the major eruptions and that the connection to the source was severed leading to Echinus' current state.

Echinus is the largest acid-water geyser known. Its waters have a pH

PH

In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 of 3.3 to 3.6, nearly as acidic as vinegar

Vinegar

Vinegar is a liquid substance consisting mainly of acetic acid and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. Commercial vinegar is produced either by fast or slow fermentation processes. Slow methods generally are used with traditional...

. The water temperature is 80.3 °C (176.5 °F).