Shell Spring in Yellowstone National Park, Wyoming Postcard

"Shell Spring, Biscuit Basin, in Yellowstone National Park, Wyoming" by Catherine Sherman. Shell Spring begins to erupt in Biscuit Basin of Yellowstone National Park, Wyoming, on an early September afternoon in 2022. Shell Spring erupts irregularly. The golden sinter lining of the crater resembles the shell of a bivalve, which gives this feature its name. Shell Spring is very irregular and the interval between eruptions changes from year to year. Before an eruption, water in the crater begins to rise and may boil. Heavy churning then occurs, setting off the first small, weak eruption. As the eruptions subside water begins to lower and drain back into the crater. The temperature of this geyser is 200°F, at an interval of 1.5 to several hours. And a duration of 20 to 90 seconds. Biscuit Basin is an isolated thermal group and is actually a part of the Upper Geyser Basin.