| Cascade Range, Lassen lies atop a side vent of where Mount Tehama once existed. Eruptions began in 1914 and culminated in 1921 with the collapse of the northern part of the volcano, Eruptions began in 1914 and culminated in 1921 with the collapse of the northern part of the volcano, pyroclastic flows, and small lava flows. Eruptions subsided in 1922. Today's park, established 1916, includes the former Lassen Peak and Cinder Cone national monuments.includes the former Lassen Peak and Cinder Cone national monuments. |
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