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 dacite lava that filled Lassen Peak’s crater. On May 14, 1915, lava began welling up and plugged the volcano’s crater. Pent-up gases within the volcano blasted and shattered the lava cap on May 19. Careening down the mountainside, 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.