The Devastated Area
Reading Peak
Reading Peak is a group of
volcanic domes composed
of light-colored lava called
dacite. These domes were
formed about 200,000
years ago and have been
reshaped by several
periods of glaciation.
Lassen Peak
This huge volcanic dome,
10,457 feet (3,187 meters)
above sea level, is one of
the largest in the world. It
is a relatively young
volcano that was emplaced
between 15,000 and 20,000
years ago, during the Tioga
glacial period. Its original
shape has been somewhat
modified by this glacial
action.
Chaos Crags
This group of six plug
domes was emplaced
about 1,100 years ago. An
undefined event about 300
years ago triggered a
rockfall avalanche that
created the Chaos
Jumbles, a two-mile square
field of volcanic rocks and
boulders. The Jumbles is
located to the west of the
Chaos Crags and not
visible from here.
Raker Peak
Like many volcanic
features, Raker Peak is
the clumination of several
events. The cliffs are a
part of a rhyolite dome
emplaced about 400,000
years ago; glacial erosion
reshaped the mass into its
present profile.
