Trestles Wave Quality

30 08 2010

Source: Google Earth

Ever wonder why the waves at Trestles don’t quite have the punch of some of its beach break brethren?

It’s not just the rock reef bottom, with its holes and mounds, that make it roll onto shore without throwing surfers for headers.  The bottom affects it before it even makes it onto the horizon.

Notice above  (courtesy of Google Earth) the continental shelf that extends out from the beach, starting at Dana Point and continuing southward.   The shelf was formed over time by the deposit of sand and silt (and rocks) from the ephemeral creeks throughout the Southern California Bight (not bite).  The Bight actually reaches from Point Conception into the northern part of Baja California.  The summer (mostly south to north) currents move the sand along the coast until it hits a projection like Dana Point.  Then, the winter (mostly north to south) currents wash the sand in the opposite direction.

We’ll talk about sand flow in more detail at another time, but the point here is that there is a shelf that extends out from Trestles for a few miles.  That shallow shelf provides resistance to incoming waves, slowing them down and flattening them out.  As a result, they just sort of roll onto the beach.

On the other hand, look at what is referred to as Newport Canyon.  Again, at another time we will discuss how Newport Canyon was formed and present some cool side-scanning sonar images that leads some to believe that the canyon was formed when the “mighty” Santa Ana River cut into the soft continental shelf over the centuries.  The point here is that the big south swells of summer run through deep water straight at the south facing beaches of Newport (“The Point”) and slam into the sand, without any shallow water resistance, forming vertical faces and those “almond eyes” that can bury a standing surfer and spit him out again.

So, if you want a mostly rolling wave, hang with the Crowd at Trestles.  If you want to take your chances in the pursuit of barrel glory, look for the deep water with no offshore island obstructions.



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