Notice too the variety of colors staining the basins. The refraction (breaking up) of light, mineral deposits and living organisms, algae and bacteria, all add their hues. The assortment of colors reflects variations in water temperature and chemistry.
As you enjoy your walk remember that Norris is a great natural preserve where nature is constantly at work designing and redesigning one of its most unusual displays. We are only visitors here and must not spoil it in any way. It also serves as a great natural research laboratory where scientists from all over the world learn more about geothermal energy. Help us preserve this unique area so that the next generation and those who follow can come and enjoy it in the same grandeur you did.
The Norris Geyser Basin is made up of two or more less separate areas called Porcelain Basin and Back Basin. Both basins are served by trails which begin at the Norris Museum and are shown on [this map]. The following briefly describes a few features in each.
THERMAL FEATURES IN PORCELAIN BASIN
VALENTINE GEYSER—Located at the base of a large pear-shaped alcove, Valentine is a typical cone type geyser that first erupted on Valentine’s Day, 1907. Its activity has varied considerably—being dormant some seasons, erratic during others, yet showing a high degree of regularity at times. During the past several seasons, it has erupted from a minimum of once every two days to a maximum of once a day. An eruption lasts 5-7 minutes and reaches a height of 20-50 feet (6-15 m.) above the seven foot cone. The eruption is followed by a steam phase lasting an hour.
LEDGE GEYSER—The largest geyser in the Porcelain Basin, changed dramatically after an earthquake that occurred June 30, 1975. In 1974 it had been erupting about twice a day, but after the quake Ledge was dormant for nearly two years. Then during the summer of 1977 it had but two eruptions. Check the prediction board at the museum to see if Ledge Geyser is active this year.
AFRICA GEYSER—named for the spring that preceded it which was roughly the shape of the continent. The spring became a geyser in February of 1971. At first it was intermittent but as time passed the periods between eruptions grew shorter until it became a constant geyser. In 1977 it was always powerful—sometimes emitting a mixture of steam and water; other times just steam.
THE WHIRLIGIGS AND CONSTANT GEYSERS—these three features seem to be interconnected. Constant Geyser, dormant for several years, reactivated in the early ’70’s and now erupts up to 30 feet (9 m.) once or twice an hour; often prior to an eruption of one of the Whirligigs. In recent years, Big and Little Whirligig have traded active periods. When one is more active, the other is less. Watch for the 15 foot (4 m.) angled plume from Little Whirligig’s orange vent or listen to the distinctive chugging produced during Big Whirligig’s splashing eruption. As with many geysers, the water level rises in these pools prior to an eruption.
EBONY AND BEAR DEN GEYSERS—are another set of related features. In the ’60’s Bear Den Geyser first appeared and as it increased in activity, Ebony Geyser became dormant. Today Bear Den Geyser erupts in bursts, arcing up to 40 feet (12 m.) from the den-like vent, four to six times daily. The death of Ebony Geyser may have been hastened by objects thrown into its vent by thoughtless visitors. This debris is cemented into place by the silica deposited from the water, choking off the vent. Minute Geyser in the Back Basin may have suffered a similar fate.