An Answer to San Clemente’s Rocky Beaches
This post is an answer to Neighbor Linda’s question she asked in my comments.
Hi surf butler. I have a question for you, not a comment. I’ve learned so much from you reading your blogs, I am sure you can answer my question. The beaches in Laguna and north of there have sandy beaches with no rocks. The beaches in San Clemente seem to be filling up with more rocks every year. My question is this: Where do these rocks come from and how long will they be here? I love San Clemente but hate the rocky beaches.
What a great question Neighbor Linda!
There are a variety of factors, including wave energy, tidal range, sediment supply, sediment type, continental shelf slope and width, and past history that characterize Rocky and Sandy coastal environments and beaches. To get a better understanding of our coastal environment here are geological factors that define rocky coasts and sandy coasts.
SANDY BEACHES AND COASTS
Neighbor Linda this explains your sandy beaches in Corona Del Mar “Big Corona” and a Laguna Beach favorite Anita beach and Main Beach.
ROCKY BEACHES AND COASTS
The pounding surf and breaking waves found on Rocky coasts have inspired ocean lovers for generations. Erosion characterizes these high energy environments which are typically located n active margins with narrow continental shelves (on account of subduction). Rocky beach coasts may be composed of any rock type (i.e., sedimentary, igneous, or metamorphic) and are usually the site of complex tectonic landforms such as faults, folds, and igneous intrusions and extrusion. Bedrock composition, climate, and wave patterns dictate the profile of rocky coasts. Resistant bedrock combined with high-energy wind and wave activity will create a steep profile, whereas easily erodible rocks in low-energy environments will create a more gradual profile.
North Beach, 204’s, Linda Lane and T-Street had an excess of rocks this summer making it harder to get to and from the water . Geologically speaking our rocky beaches are a result of Erosion.
SAN CLEMENTE’S SHRINKING ROCKY BEACHES
Yes, San Clemente’s beaches have been wilting away slowly with rock and kelp flies for the past ten years . This year there seems to be even more rocks and kelp flies at my go to beach Linda lane. The question that Neighbor Linda asked just so happen to hit home here in San Clemente. City officials are currently awaiting word on federal funding to replenish San Clemente’s beaches.
San Clemente’s beaches are rocky because of beach erosion . Our Beach Erosion however was man-made by the Army Corps of Engineers when they turned the Santa Ana River into a concrete channel. This channelization unintentionally robbed our beaches of fresh supply of sediment that activated erosion. (see Rocky Beaches)
The federal government is now obligated to make sure San Clemente’s beaches don’t wash away because it was the Army Corps of Engineers that turned the Santa Ana River into a concrete channel.
The Army Corps of Engineers Sand Replenishment Project would allow corps vessels to hull massive amounts of sand to 50 foot wide swath from Linda Lane to south of T-Street every six years for 50 years.
So, Neighbor Linda the rocks on our beaches are a result of beach erosion. Federal funding is a multi step process, but if all goes right San Clemente beaches will begin their sand replenishment as late as 2015 or early 2016.
This was a great learning experience! I encourage all readers to ask S C Surf Butler questions about their local beaches.
I’ll see you at the beach!!
This is my local spot at the beach!!