Lassen produced California's most recent volcanic eruption, in 1915. In September 2009 we visited in order to study magma mingling and mixing, characterize the oxidation of fall deposits in order to better constrain eruptive history, and characterize the evolution of clast roundness as particles are transported in pyroclastic density currents.
Lassen in the background
A bomb, with cinder cone in the background
Oxidized pumice that fell on a still-hot lava flow
Enclaves in dacite
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