All beach sand and pebbles are
protected resources. Please do not remove sand and pebbles from the
beach.
Rodeo Beach separates Rodeo Lagoon from the ocean. Throughout
most of the year there is not enough water flowing down from the
catchment to fill the lagoon and break through the sand berm that
blocks the opening of the lagoon to the ocean. Usually the water
that flows into the lagoon moves underground through the beach sand
into the ocean. Only following winter storms when there is high
flow in the creek does the lagoon fill and overflow the sand berm
and empties into the ocean. For a few hours the flow erodes through
the beach sands creating a channel that empties into the ocean.
Thus it is actually unlikely that you will find a channel at the
beach. The steep banks of the channel expose the layering buried
under the sand.
Once the flow of the creek goes down again, the waves begin to
transport sand back up onto the beach. The waves breaking on the
beach carry sediment up the beach where it meets the opposing flow
coming out of the lagoon creating an area of low velocity water.
The decrease in velocity decreases the amount of sediment the water
can carry, so the sediment is deposited in the channel slowly,
building the berm back up.
The berm gets higher only during high tide, so minor differences
in sand composition between high tides, sand grain size differences
between incoming and outgoing tides due to wave energy differences,
and the accumulation of additional material (wind blown sand, wood,
etc.) on top of the sand during low tide create the layering
beneath the surface of the beach. These layers, called laminiations
because they are so thin, are present beneath the entire beach.
If the beach were to be buried, the laminations would be
preserved and become laminations in sandstone that could be used
later to help reconstruct the environment in which the sand is
deposited.
Logging questions:
- The text "GC3BM1J Rodeo Lagoon Sand Berm" on the first
line
- The number of people in your group.
- What is the condition of the berm?
- If there is a channel, describe (or better yet photograph) the
laminations. Be sure to stay safe while doing this.
- All beach sand and pebbles are protected resources. Please do
not remove sand and pebbles from the beach.