John Turbeville
MiraCosta College
Stop
2 is at the overview area to the middle of the sea-cliff on Trail
#1. At this stop, we will look at
slumping in the Monterey Formation. The slumping (1) is progressively
moving the sea-cliffs toward the campground, the railroad and I-5. This type of mass wasting (slumping (2)is common in soft
sediments.
This shot is looking north-west from
Trail#1. You can see the large slumps in the foreground. These areas are
underlain by the very soft Monterey Formation. The Cristianitos
Fault is located where you see the cliff as being near vertical directly INLINE
with the nuclear powerplant. On the other side of the Cristianitos
Fault, the sea-cliff is near vertical as the base is composed of the tanish San Mateo Formation.
This shot is looking south-east from
Trail #1. This area is underlain by the very soft Monterey Formation. Large
slumps dominate the landscape here. You can see some backwards rotation in the block
that is in the middle of this picture.
Walking down the trail to the beach you
pass some large exposures of alluvial deposits. These form the upper portion of
the sea-cliffs in the San Onofre area. They are locally derived and very young
deposits.
Notice how poorly sorted and angular the
rock fragments are in the alluvial deposits.