The Cliffs of the Lost Coast Are Collapsing Faster Than Any Other in the Golden State

The steep cliffs along Sinkyone Wilderness State Park. [Photo by Matt LaFever]

Researchers used a laser-imaging technology known as LiDAR (Light Detection and Ranging) to measure cliff erosion and retreat, comparing findings gathered between 2009-2011 to more recent data from 2016.

Examples of change detection near a) Point Arguello ,b) Martin’s Beach c) Usal Beach d) King Range, and e) Centerville Beach area [Graphic from the Scripps Institution of Oceanography]

Humboldt County’s hotspots include the northern stretch of the Lost Coast known as King Range, Centerville Beach located five miles west of Ferndale, and the McNeil Creek area north of Trinidad Head. 

Cal Poly Humboldt Professor Lori Dengler has spent her career exploring the North Coast’s seismic activity and the tsunamic hazards along our coastline. The coastline between 39-41 degrees latitude “consistently has the largest” waves, Professor Dengler said. With these larger waves plus high rainfall typical of the region, “you have all the ingredients for high erosion.” 

For those that might be concerned that cliff retreat and sea-level rise could erode the iconic cliffs of the Coast, Professor Dengler said she doesn’t “think the bluffs will erode away completely anytime soon – the uplift is growing the coast at the same time.”

Del Norte County made the list approximately two miles north of where the Klamath River enters the Pacific. Those cliffs are also crumbling faster than most of the others in California.

The Lost Coast is California’s most remote and least developed coastline. The untouched, primordial condition could be one of the contributing factors to its higher rate of retreat. The totality of the Lost Coast is considered “unarmored”, as opposed to “armored” which describes the installation of seawalls and riprap at the base of coastal cliffs to mitigate erosion. Cliff armoring is a common strategy employed in Southern California to reinforce and mitigate erosion, often associated with seaside development. 

Likely, the last photo of the Centerville Cross as taken from the beach just before it was rescued from a crumbling cliff in 2017. [Photo by Dorre Kidd Howard]

Another commonality noticed by researchers between cliffs collapsing the fastest might seem counterintuitive: cliffsides fronted by beaches retreated twice as fast as those without. Though a wide, sandy beach could suggest a barrier to protect cliffs from wave action, researchers found that beach sand, stirred up by incoming waves, acts an abrasive, eroding the lower sector of a cliff. Caspar Beach, Usal Beach, large swaths of King Range, and Centerville Beach all feature sand beaches that end abruptly at steep cliff walls.

In 2016, Centerville Beach’s eroding cliffs threatened a historic cross which memorialized the 1860 sinking of a steamer known as the Northerner off the coast. The cliff underneath where the cross had been installed began to collapse and the Native Sons of the Golden West volunteered to bring the cross to safety in January of 2017 before it tumbled down.

This research was the outgrowth of California State Assembly Bill AB-66 which funded scientific research to build a deeper understanding of California’s coastline, coastal bluff failures, and the possible development of future alert systems to warn communities of cliff failures. Essential infrastructure including highways, public access points, homes, military bases, power plants, and railways are located along California’s coastline and are vulnerable to erosion, retreat, and collapse.

Cliffs meet the Pacific Ocean along King Range National Conservation, the BLM managed northern stretch of the Lost Coast [Picture from the Bureau of Land Management]

A map from Scripps graphically demonstrating the Lost Coast’s significantly higher rates of cliff retreat than the rest of the California Coast

Now, the stretch of coastline referred to as the Lost Coast which hosts multiple cliff retreat hotspots is actually made up of two separate designated wilderness areas. 

The federally managed King Range Wilderness makes up the northern section of the Lost Coast, beginning just south of where the Mattole River enters the Pacific and ending near the town of Shelter Cove.

The southern section of the Lost Coast lies within Sinkyone Wilderness State Park, managed through a partnership of ten indigenous tribes known as the InterTribal Sinkyone Wilderness Council and California State Parks. Sinkyone Wilderness begins at Needle Rock Visitor Center and runs south to Usal Beach, a popular car camping destination.

Usal Beach, the southern terminus of the Lost Coast [Photograph from CAL FIRE Mendocino]

Researchers behind the Scripps study intended for their data set to inform coastal planning and development, essential in California where millions live a stone’s throw from where the American continent drops off into the Pacific. The oceans are rising. Policymakers in Mendocino and Humboldt County have already begun to consider the implications of this on our coastlines. Knowing sections of our coastline are crumbling at a record rate, perhaps local leaders will face the challenge of mitigating the negative effects of sea-level rise with a renewed sense of urgency.