Lurching and hissing, this 300 ton chunck of lava was swept
down the side of Lassen Peak by a massive mud slide.
On May 19, 1915, molten lava welled up within Summit
Crater, quickly melting the deep snow pack on the side of
the peak and triggering an avalanche of slush and rocks.
This huge boulder was still scalding hot 40 hours after its
wild, 5 mile ride.