Biscuit Basin is part of Upper Geyser Basin.
The following information was taken from the Old Faithful Area Trail Guide, which is available at the Old Faithful visitor center.
Three miles (5 km) north of Old Faithful is Biscuit Basin, named for the unusual biscuit-like deposits that used to surround Sapphire Pool. Following the 1959 Hebgen Lake Earthquake, Sapphire erupted, and the "biscuits" were blown away; it last erupted in 1991. Sapphire remains one of the most beautiful blue pools in the park. Mustard Spring provides a bright color contrast, and Jewel Geyser adds excitement as it erupts every 7-10 minutes.
Hydrothermal features are fragile rarities of nature. Yellowstone preserves the largest collection of hydrothermal features on the planet. You have an unparalleled opportunity to view hot springs, geysers, mudpots, and fumaroles in a natural setting.
Change takes place naturally in a hydrothermal area, but people can disrupt these processes and cause irreparable damage. Rocks, sticks, and other objects thrown into a hydrothermal feature may be permanently cemented in place, choking off water circulation and ending all activity.
For the sake of all who follow, never throw objects into any feature. Stay on established walkways for your safety and to protect fragile formations that have formed over thousands of years.
It is illegal to collect any natural or cultural objects or to remove, deface, or destroy any plant, animal, or mineral in Yellowstone's hydrothermal areas. Bring drinking water; take out all trash.
While viewing or photographing the area, protect your camera, glasses, and binocular lenses from hydrothermal heat and stray.
Toxic gases exist in Yellowstone. Dangerous levels of hydrogen sulfide and carbon dioxide have been measured in some hydrothermal areas. If you feel sick, leave the location immediately.
Help preserve Yellowstone for the future.