Mount Tehama

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Mount Tehama (also called Brokeoff Volcano or Brokeoff Mountain) is an eroded extinct andesitic stratovolcano in the Cascade Volcanic Arc and the Cascade Range in Northern California. Part of the Lassen volcanic area, its tallest remnant, Brokeoff Mountain, is itself the second highest peak in Lassen Volcanic National Park and connects to the park's highest point, Lassen Peak. Located on the border of Tehama County and Shasta County, Brokeoff's peak is the highest point in the former. The hikers that summit this mountain each year are treated to "exceptional" views of Lassen Peak, the Central Valley of California, and many of the park's other features. On clear days, Mount Shasta can also be seen in the distance. Brokeoff Volcano was active from 590,000 to 387,000 years ago, during which period it erupted numerous flows with compositions ranging from basaltic andesite to dacite. At its peak, Brokeoff Volcano reached an estimated height of 3,350 metres (10, 990 ft) and had a basal circumference of approximately 12 kilometres (7.5 mi). At approximately 313,000 years ago volcanism began shifting to the northeast of Brokeoff Volcano, with volcanism currently focused around the modern Lassen Peak. Following the end of volcanism at Brokeoff Volcano, cooling magma beneath the surface continued to drive hot, highly reactive hydrothermal fluids circulating near the central vent of the vo

Adapted from Wikipedia (CC BY-SA). Photography via Wikimedia Commons.