2006 39c Steamboat, Tallest Geyser

U.S. #4059
Steamboat Geyser
Wonders of America

Issue Date: May 27, 2006
City: Washington, DC
Quantity Issued: 204,000,000
Printed by: Avery Dennison
Printing Method: Photogravure
Perforation: Serpentine die cut 10 ¾
Color: Multicolored

Yellowstone National Park is home to nearly half of the world’s estimated 1,000 geysers, including Steamboat Geyser. Members of the Hayden expedition named the geyser for its steamboat-like appearance in 1878.

Steamboat Geyser is the world’s tallest active geyser. Although minor eruptions of 10 to 40 feet are common, the geyser is capable of sending massive plumes of steam 300 feet into the air. These major eruptions last 3 to 40 minutes and are followed by powerful jets of steam lasting up to 48 hours.

Eruptions of the Steamboat Geyser are unpredictable. Major eruptions have been recorded in intervals ranging from four days to 50 years. Indeed, the geyser remained dormant from 1911 to 1961.

Geysers are formed when cool water drains deep into the earth until it reaches very hot rocks. The rocks heat the water at the bottom, but the lowest water cannot boil because of the weight of the water above. The heat at the bottom then increases far above the boiling point, turning the bottom water into steam.

Rising steam bubbles from the superheated water splash water out over the top, reducing the pressure on the water beneath and allowing the water below to expand. The result is an eruption of steam and water.