Younger
Lagoon is part of a system of marine terraces along the California
coastline that were formed approximately 100,000 years ago as a
result of the uplifting of land caused by plate tectonics, as well
as climatic changes facilitating a lowering of sea level.
Over
one night in February, 1992, a storm collapsed the rock arches on
the beach at Younger Lagoon and washed away the remains without
a trace.
Over
time the waves breaking on the beach have pushed sand up into the
channel, forming a barrier between the fresh water of the lagoon
and the salt water of the ocean for much of the year. This barrier
is known as a berm, which consists of an underlying layer of bedrock
and a sand layer on top. The rock shelf usually inhibits the exchange
of salt and fresh water, however there may be some seepage of seawater
through the sandy layer.
Marine
terraces are ancient shorelines consisting of a relatively flat
wave-cut platform (rocks in the surf zone that have been eroded
by waves). This photo was taken at the cliffs near Long Marine
Lab.
Sea
arches and caves are a characteristic feature of Santa Cruz County
coastline geology.