They shoot molten lava and toxic gases miles into the atmosphere and when the lava is too thick to run over the top, it can create what geologists like Dr. Pat Abbott call a plug dome volcano.

The park's namesake peak is the one of the largest plug dome volcanoes in the world — a type of volcano that grows in size from layers of its own lava building on top of each other over time.

Lassen Volcanic is one of the few areas in the world where all four types of volcano can be found—plug dome, shield, cinder cone, and stratovolcano. Accommodations Tours/Experiences Flights Car ...