|
The fickle nature of geysers Story and Photos By MICHAEL MILSTEIN Gazette Wyoming Bureau YELLOWSTONE NATIONAL PARK - Old Faithful remains quite faithful, but some of the famous geyser's most predictable neighbors in Yellowstone National Park's Upper Geyser Basin have grown decidedly less so in recent weeks.
Its schedule has grown so inconsistent that in recent weeks rangers have stopped posting eruption predictions on a signpost at the popular geyser and at the Old Faithful Visitor Center, explaining to visitors that Castle appears to be out of kilter. "Castle Geyser is not predictable right now," says a sign tacked to the visitor center bulletin board where rangers usually track Castle's schedule. "Recent intervals between eruptions range from 12-1/2 to 21-1/2 hours!" In place of its 70- to 80-foot high eruptions, the geyser has spouted steam with occasional splashes of water, a display more common in the park's early decades. Experienced geyser watchers noticed other changes in some of the Upper Geyser Basin's best-known performers at about the end of April, the same time Castle went on the fritz. Grand Geyser, the tallest predictable geyser in the world, suddenly slowed. Instead of erupting roughly every six to eight hours, it's now erupting about every 10 to 14 hours and a few times in recent weeks has waited more than 19 hours between eruptions. On Sunday, many onlookers wandered off when Grand had not erupted more than three hours into the four-hour eruption window predicted by rangers. Although Echinus Geyser earlier this year strayed from its regular schedule in Yellowstone's Norris Geyser Basin, the park's hottest and most dynamic geyser basin, such sudden changes are more unusual in the Upper Geyser Basin, where Old Faithful remains the star. "When you see things like what's been happening during the past few weeks, it's really interesting because things here don't usually change so much," said Mike Keller, a dedicated geyser watcher who lives most of the year in Yellowstone and spends much of his free time tracking geysers. Old Faithful has remained its regular self, waiting an average of about 80 minutes between eruptions, said park ranger Ann Deutch. The average has stayed generally consistent since an earthquake early last year slowed Old Faithful and temporarily reactivated nearby Cascade Geyser, which has since gone silent. The new slowdown by Castle and Grand does not suggest that the geysers will shut down entirely: Castle's nearly 15-foot-tall cone suggests it has erupted for thousands of years. The changes in schedule, however, illustrate that geysers are a product of Yellowstone's otherworldly and ever-changing geology. And as Castle and Grand have become more fitful, other geysers have picked up their pace or become even more regular. Beehive Geyser, which jets water up to 200 feet high from a beehive-shaped cone across the Firehole River from Old Faithful Geyser, has recently erupted on an unusually reliable and rapid pace of every 12 to 13 hours, so regular that it has become roughly predictable. Beehive almost always offers advance notice of an eruption by spitting water from a small nearby vent known as "Beehive's Indicator" about 10 to 20 minutes before Beehive itself erupts. And Little Brother Geyser, which lies along an access road serving the parking lot in front of Old Faithful Inn, began erupting about the end of April for the first time since 1983. Little Brother erupts some 15 feet high every seven to 17 minutes. It is so named because of its location near a set of springs and geysers called the Three Sisters. Green Spring, a normally quiet pool in Black Sand Basin west of Old Faithful, also began an unusual series of eruptions first noticed in April. Even more intriguing to geyser gazers is an apparent shift of energy back to Giant Geyser, a spectacular but infrequent performer that spews a water column more than 200 feet high. Giant erupted last Oct. 15, then seemed to lose its energy to a set of geysers across the Firehole River known as the Purple Pools, Keller said. On April 26, one of the Purple Pools stopped overflowing, and the following day Giant underwent a "hot period," when many smaller vents on its broad sinter platform began spouting. Giant erupts only during one of its hot periods. The geyser's rumblings increased over the next two weeks until finally, during a hot period on May 9, Giant erupted for the first time in more than six months. There's no way to prove any connection between all the changes that hit the Upper Basin in late April, but the timing has many geyser observers wondering. "In some features, change is a fast process and in some it's a slow one," Keller said. "Part of the fun of it is trying to figure that out." Historically, when Giant has erupted in the spring as it did this year, it has stayed active into the fall, promising geyser gazers and other Yellowstone visitors even more spectacular shows.
|
