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California’s far northern cliffs are eroding faster than elsewhere in the state

By Tara Duggan, San Francisco Chronicle, August 9, 2022

“In the Bay Area, locations with some of the highest rates of clifftop erosion include Daly City, Pacifica, and Bodega Bay, according to a study published this month by researchers at Scripps Institution of Oceanography at UC San Diego. The highest erosion rates were found near Humboldt Bay and in a few remote locations in Del Norte County.

“Far Northern California may have the worst erosion because it has more rainfall and larger waves, but more surveys will be needed to demonstrate a direct relationship, said Zuzanna M. Swirad, one of the authors.

“Cliffs next to sandy beaches also showed the highest rates of erosion.

“ ‘This finding is counterintuitive, because wide beaches can protect cliffs from wave action. However, waves can also use beach sand as an abrasive to erode the lower cliff,’ read the study, which was published in the journal Geomorphology.

“The results of the study … are presented in an interactive map.

“The researchers say it is the first study to use high-resolution data to analyze cliff erosion all along the coast.

“The time period the study looked at — when the relatively new [high-resolution data] became available — may not be representative of the overall picture of erosion on the coast, said Gary Griggs, professor of earth sciences at UC Santa Cruz, who was not involved in the study.”

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