Grotto Geyser is a fountain-type geyser located in the

Upper Geyser Basin The geothermal areas of Yellowstone include several geyser basins in Yellowstone National Park as well as other geothermal features such as hot springs, mud pots, and fumaroles. The number of thermal features in Yellowstone is estimated at 10, ...

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in the

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. Grotto Geyser is the namesake for the group of geysers that includes Grotto Fountain Geyser, South Grotto Fountain Geyser, Indicator Spring, Spa Geyser, Startling Geyser, and Rocket Geyser.

History

On September 18, 1870 members of the Washburn-Langford-Doane Expedition entered the Upper Geyser Basin where in a day and a half of exploration, they named seven geysers of which ''Grotto'' was one.

Nathaniel P. Langford Nathaniel Pitt Langford (August 9, 1832 – October 18, 1911) was an American explorer, businessman, bureaucrat, vigilante and historian from Saint Paul, Minnesota who played an important role in the early years of the Montana gold fields, terri ...

described the ''Grotto'' in his 1871

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account:

"The Grotto" was so named from its singular crater of vitrified sinter, full of large, sinuous apertures. Through one of these, on our first visit, one of our company crawled to the discharging orifice; and when, a few hours afterwards, he saw a volume of boiling water, four feet in diameter, shooting through, it to the height of sixty feet, and a scalding stream of two hundred inches flowing from the aperture he had entered a short time before, he concluded he had narrowly escaped being summarily cooked. The discharge of this geyser continued for nearly half an hour.

Eruptions

Grotto Geyser erupts about every eight hours. The interval between eruptions is longer after a longer eruption. The eruptions are about high and can last from about 1 hour to more than 10 hours long, although there have been eruptions that lasted more than 26 hours.

Sequence

Grotto fountain geyser 20100825 173237 1

Grotto Geyser is connected with at least five other geysers in the surrounding area. Eruptions are usually preceded by an eruption from Grotto Fountain Geyser, or both Grotto Fountain Geyser and South Grotto Fountain Geyser. But if the latter erupts on its own, it will delay both eruptions from Grotto Fountain Geyser and Grotto Geyser itself. After Grotto has a short mode eruption, which lasts about 1 to 2 hours, Rocket Geyser usually has a major eruption. Approximately three-quarters of Grotto's eruptions are short mode. Grotto Geyser and Rocket Geyser erupt together. When Grotto Geyser has a long mode eruption, which lasts from 6 to 12 hours, Spa Geyser, instead of Rocket Geyser, erupts.

Connection with Giant Geyser

Grotto is significant beyond its own considerable size because of the interactions between its own eruptions and those of nearby Giant Geyser, one of the world's most powerful geysers. Giant erupts only during so-called "hot periods," times of intensified activity and rising water among the smaller geysers surrounding Giant. Most hot periods do not lead to Giant eruptions, but Giant eruptions frequently start during the hot period immediately following the start of a Grotto eruption. Additionally, the long, "marathon" eruptions of Grotto are commonly followed, a few hours after they end, by a particularly intense "recovery hot period" in the Giant complex that may instigate a Giant eruption. Giant eruptions may also occur 4 to 5 hours after the start of a Grotto marathon eruption.

Physical structure

Grotto Geyser's cone is nearly high. The odd shape comes from sinter accumulating over dead tree stumps as the geyser erupted.

References