The coastal cliffs in Ocean Beach are seriously eroding.
Nowhere is that more apparent than the tarp-covered area just south of Ocean Beach Pier, where crumbling cement, rock and dirt have fallen creating a debris field on the sandstone below.
Patrick Abbot, a geology professor at San Diego State University who’s authored a textbook on local geology, including coastal erosion, explained what is happening to Ocean Beach’s cliffs.
“The geological ‘problem’ is young, soft, weak sandstone above and old, hard, strong sandstone down low,” Abbot said. “The young weak sandstone has water draining down through it (both from humans and nature) that moves/erodes sand grains weakening the cliff area.”
Abbot said tarps covering the eroding bluffs “are more for psychological effect than cliff strengthening.”
The geologist gave his bottom-line evaluation of the problematic landform.
“It is a weak area that erodes easily,” he said. “If erosion is to be slowed significantly, massive structures would need to be built at great expense and loss of beauty and recreational opportunities, all requiring permission from the Coastal Commission.”
Abbot added he’s been around long enough “to see buildings collapse over this cliff area, then after a few-years wait, new buildings are constructed above the retreated cliff face.”
Regarding the eroded cliffs south of OB Pier, Tim Graham, city public information officer, said: “The initial assessment is that the two walls may have failed due to saturation of the soil as a result of the rains as opposed to erosion. The walls, possibly built in the ’50s or ’60s, were likely built originally in an effort to fortify the properties above. We (city) are still trying to track down when the walls were actually put in place, and who constructed them.”
Graham added existing property owners on the bluff top have “secured the services of a geotechnical engineer who has taken a look at the walls, and intends to make the repairs to the walls himself and secure the necessary permits to do so. We’re trying to find out where they are in that process.”