Big waves add to noticeable erosion of Bird Rock
By all accounts, there is a little less substance to Bird Rock’s most notable landmark these days.
“I’ve watched it go from a very small opening with water slipping through it at a certain juncture, to the day the largest chunk fell, to this past week when those chunks have now disappeared with the heavy surf,” said Trent Wagenseller, a La Jolla Realtor who lives on Dolphin Place, about Bird Rock, the coastal landform from which the La Jolla neighborhood derives its name. “It started as a crease in the rock that allowed the water to push back and forth. There’s another crease showing up in it now that’s allowing water back and forth. It’s changing drastically before our eyes.”
Sandie Kindred, another neighbor who lives within viewing distance of the huge community namesake rock, which is a favorite perch of the brown pelican and other bird species, scores of which can be seen daily there, has noticed a big change in it, of late, too. “We look right out at the rock every day,” Kindred said, “and we’ve definitely seen that the hole in the rock has gotten a lot larger in the last month or so.”
Kindred and her family first began to notice some deterioration in Bird Rock’s rock about 10 months ago. She’s taken photos of it which show the difference in its structure today. “It’s a noticeable difference,” she said. “It has been fun seeing the change in the rock, but at the same time, you realize what a long time it takes to make any change. To see it happening all at once is amazing.”
Bird Rock’s distinctive rock can be easily glimpsed from the platform and stairs of the sewer pump station at the end of Bird Rock Avenue which meanders down the cliff face to the rock-strewn beach below.
“It’s a huge rock but only at extreme low tides can you get out and walk the rock and climb on top,” said Wagenseller.
Don Schmidt, a Bird Rock resident and La Jolla Historical Society boardmember, concurred with his neighbors that the high-profile coastal rock is rapidly undergoing a geological transformation. “I wouldn’t say it’s breaking up,” hedged Schmidt, “but the other day I thought I was going crazy having breakfast down on the 5500 block of Calumet, and from the deck where I live (I have a pretty good shot of the Bird Rock) I saw waves through it, and I’ve lived here since the early ‘90s. Have I missed something? Maybe that hole has been there.”
Richard Seymour, research engineer at Scripps Institution of Oceanography at UC San Diego, said whatever metamorphosis Bird Rock is undergoing is just part of the natural order of things with beach erosion being accelerated by heavy winter tidal action. He noted Bird Rock was not always an isolated landform.
“At some point, a long time ago, that was part of a cliff,” said Seymour, “and it survived because it’s a lot harder than the stuff that was around it. In terms of sudden increases or decreases in the local volume of the cliff, this may or may not be related to the local wave climate. In time, if there’s a place that wants to erode, it eventually reaches its time when that last little property erodes away, that chunk falls into the ocean. That could happen on a small-wave day or a big-wave day, though it’s more likely to happen on a big-wave day.”
Seymour described the wave climate over the last decade along San Diego’s coastline as “remarkably energetic.”
“We’ve had a lot of big storms in Southern California,” he said. “So I would anticipate we would see, in the weakest parts of the cliffs, some evidence of erosion. There’s been more erosion in the last 10 years than in the previous 10 years.”
Graham Kent, a research geophysicist with Scripps Institution of Oceanography at UC San Diego, noted La Jolla, itself, has a unique geological rock pattern. “All of these rocks have undergone a fair bit of compaction and consolidation,” Kent said. “Down at the Cove, there’s a lot of sand and silt, so that’s pretty competent rock today laid out on the seafloor. But the rocks are actually older over by Black’s (beach). That’s just dynamic because of all the pop up along the Rose Canyon fault. That stuff is deeper rocks which are now at the surface and they erode because you have the big waves.”
Coastal cliffs can fail at times, said Kent, because they get undercut by strong wave action. “Then, obviously, they’re not being supported any longer,” he said, “and they collapse. This is a fruitful time for surfers - and people who like erosion. Everything is a balance, but over time, the cliffs will erode. That’s the price of living in an area that has a pretty view. The cliffs don’t erode too much in Kansas.”