Travel Reference
In-Depth Information
• 385°F (196°C) at 813 t (248 m) deep
• 460°F (238°C) at 1088 t (332 m) deep
2. Long history
Geoscientists infer from sinter cobbles found in glacial
moraines
that geothermal activity
at Norris may have been continuous since 150,000 years ago.
3. No big formations and few predictable geysers
Although geyserite is deposited at Norris as at other geyser basins, Norris lacks the tall or
grotesque formations you see in Upper Geyser Basin. Much of what looks like sinter at
Norris is actually acid-leached volcanic rock, especially Lava Creek tuff. There are at least
70 geysers at Norris, but very few are predictable.
4. Change is the only constant
The whole area is so dynamic that changes in the hot springs occur constantly and rapidly.
Some changes can be attributed to earthquake activity, but many are still puzzling to geo-
logists and geochemists. Some of the variables they study here are temperature, chemical
composition, amount of water and discharge, amount of sinter deposition, and acidity/al-
kalinity
(pH
).
5. Unique locale
Norris is uniquely situated at or near the intersection of three geologic features:
• the northwest rim of the Yellowstone Caldera
• the long Norris-Mammoth corridor, a zone of faults running north-south, where
the earth's surface has subsided
• a seismically active fault zone that stretches east-west between Norris and Hebgen
Lake.
6. Special springs
Some springs far out in the One Hundred Spring Plain (to be visited only with a ranger
or other knowledgeable person) show truly unusual phenomena. Realgar Springs deposit
red and orange material that may be a previously unknown form of
arsenic sulfide.
Large,
circular Cinder Pool suspends on its surface tiny black hollow spheres, probably made of
elemental sulfur colored by iron sulfide. And then Sulphur Dust Spring's bottom is covered
with powdery, pale yellow, elemental sulfur.
7. Seasonal disturbance
