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Lassen Volcanic National Park
Explore the Hydrothermal Areas
 
mud pot at Bumpass Hell
NPS Photo
This mud pot can be seen from the Bumpass Hell boardwalk.
The remarkable hydrothermal features in Lassen Volcanic National Park include roaring fumaroles (steam and volcanic-gas vents), thumping mud pots, boiling pools, and steaming ground. Water from rain and snow that falls on the highlands of the park feed the hydrothermal system.  Once deep underground, the water is heated by a body of hot or molten rock beneath Lassen Peak.  Rising hot water boils to form boiling pools and mud pots.  Super-heated steam reaches the surface through fractures in the earth to form fumaroles such as those found at Bumpass Hell and Sulphur Works.  These features are related to active volcanism and are indications of the ongoing potential for further eruptions from the Lassen "volcanic center."
 

The areas of hydrothermal activity in Lassen Volcanic include:

 

 
 
Hot Water in Lassen Volcanic National Park
Fumaroles, Steaming Ground, and Boiling Mudpots: Download the 2.5MB PDF File
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john muir posing on rock in black and white photo  

Did You Know?
John Muir visited Lassen Volcanic National Park and wrote about his experience in the book Mountains of California. "Miles of its flanks are reeking and bubbling with hot springs, many of them so boisterous and sulphurous they seem ever ready to become spouting geysers..."

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Last Updated: June 01, 2007 at 12:15 EST