OregonHiker's photos with the keyword: volcanic

Sulfurous vapors emmanating from Bumpass Hell in Lassen National Park.

Bumpass Hell in Lassen National Park. A hydrothermal area with lots of boiling pools and hydrogen sulfide stench.

Hiking towards Broken Top volcano (background) on the Tam McArthur Rim trail.

Painted Hills of John Day Fossil beds (that John Day had nothing to do with). They are just named for a nearby John Day river. The hills are made of volcanic ash from multiple eruptions from 18 to 35 million years ago.