Hot Rock - Lassen Volcanic National Park - California - Photos Then and Now on Waymarking.com

Original photo is on history sign at the Hot Rock turnout in Lassen Volcanic National Park. On the night of May 19-20, 1915 an eruption at the summit of Mt. Lassen resulted in an avalanche/mudflow depositing in many large hot boulders being deposited along Lost Creek. Two days later (morning of May 22) B.F. Loomis photographed this large boulder and that afternoon the final large eruption of Mt. Lassen occurred, which a couple of feet of material around the base of the boulder. Today, the forest which was destroyed the night of May 19-20 has returned to obscure the view of Lassen Peak.

Text of sign - Hot Rock

Following the May 1915 Lassen Peak eruptions, B.F. Loomis and other local residents discovered several massive hot rocks resting in the valley miles from the volcano. This hot rock is a piece of the dacite lava that filled Lassen Peak’s crater. On May 14, 1915, lava began welling up and plugging the volcano’s crater. Pent-up gases within the volcano blasted and shattered the lava cap on May 19. Careening down the mountainside, the hot lava rocks touched off a snow avalanche. The avalanche carried this 300-ton rock five miles from Lassen Peak to this location, where it settled, sizzled, and cooled.
B.F. Loomis reported that the rock in this photo was “still sizzling in the water” some forty hours after it was ejected from the volcano’s crater.
The destructive forces that moved this cabin sized rock destroyed a three-square-mile swath, now called the Devastated Area. Visited the Devastated Area Trail two miles south of here.

Year photo was taken: 1915

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Date Logged Log User Rating   09/16/2013 Volcanoguy visited it