User:Hog Farm/Geology of the Lassen volcanic area
The geology of the Lassen volcanic area presents a record of sedimentation and volcanic activity in the area in and around Lassen Volcanic National Park. Heat from subducting tectonic plates has fed scores of volcanoes over at least the past 30 million years, including these in the Lassen volcanic area. Flows of lava covered areas of a lahar-formed formation to form the lava plateau that the park sits on. About 600,000 years ago, Mount Tehama started to rise in the southwestern corner of the park. Roughly 27,000 years ago, a lava dome pushed through Tehama's former flank, becoming Lassen Peak. Phreatic (steam explosion) eruptions, lava flows, and cinder cone formation have persisted into modern times, particularly the eruption and formation of Cinder Cone and the early 20th-century eruption of Lassen Peak. The only activity since then has been from mud pots and fumaroles. The potential exists for renewed vigorous volcanic activity that could threaten life and property in the area. (Full article...)