Castle Rocks is 12 miles east of Mt. Jefferson, in the central
Cascades of Oregon. The area contains volcanic rocks ranging from
mid-Miocene to Holocene in age. These rocks record alternating
periods of tholeiitic and calc-alkaline volcanism.
The oldest rocks in the area range from basaltic andesite lava
flows to...
The Whittier fault forms the central part of a fault system extending
from the East Montebello fault at Whittier Narrows to the Elsinore fault,
which is traced as far as the Mexican border. The Whittier fault forms a
restraining bend in this fault system, resulting in uplift of the Puente...