Since then, the volcano has been dormant, although some steam still rises from small vents in its summit and on its flanks. Pumice ejected during the 1915 eruption of Lassen Peak is conspicuously banded with light streaks of dacite and dark andesite, which appears to represent two distinct magmas imperfectly mixed during the eruption. The 1915 eruption of Lassen Peak was the second most recent volcanic outburst in the contiguous 48 U.S. states (after the 1980 eruption of Mount St. Helens in Washington).