Biscuit Basin: - Map
Biscuit Basin can be reached by road or by trail. There are a number of small and interesting geysers in this basin. the main group of the basin is traversed by a short boardwalk.
Jewel Geyser: [Pictures] [Map]
[Jewel Geyser description provided by Ralph Taylor.]
Jewel Geyser has long been considered the major geyser of the Main Group of Biscuit Basin. Originally named Soda Geyser by the Hayden Survey, the name was changed to Jewel Geyser by Hague in 1887. For all of its known history, Jewel has been a regular, frequent performer. The only known exception was a period of steady spouting following the 1959 Hebgen Lake earthquake.
Jewel Geyser is located at the top of the boardwalk hill from the Biscuit Basin parking lot, past Sapphire Pool and the junction of the boardwalk loop. Jewel erupts from a nearly circular sinter shield about 10 meters in diameter. There is an irregular crater in the form of a long narrow basin with the long axis running generally north to south. The inner part of the formation is a smooth appearing sinter mass surrounding the inner crater. The outer part of the sinter shield consists of sinter lumps and nodules, terminating in a ring of sinter sand. The outer limits of the splashing of the eruptions is clearly marked by larger sinter nodules. The outer portion of the sinter shield is convoluted and covered by small sinter knobs, perhaps the jewels for which the geyser was named.
For years, Jewel erupted from a full pool. The eruption cycle began with a gradual rise in the water level. The water gradually rose until the sinter knobs near the vent were nearly submerged. The water then welled up rapidly; surging and doming over the vent for a minute or two before the start of the eruption. The eruption itself began with a sudden jet of water bursting upwards at an angle to the southwest. The eruptions consisted of from one to eight short bursts, each lasting from three to eleven seconds, separated by five to fifteen seconds. The bursts reached anywhere from two to ten meters in height. The bursts were small (staying in the inner crater), medium (landing on the inner sinter splash pan), or