Año Nuevo Geology Walk, and Escaping Radioactive Death

The things you learn on a Coastal Geology Walk at Año Nuevo State Park.

Goat Trails
by Ryan Masters

Oct. 24, 2014—Because of our brief lifetimes, human beings tend to react strongly to short-term, rapidly unfolding threats. Meanwhile, we are far less responsive to slow-moving and more abstract forms of change. To wit, we are a bunch of self-absorbed drama queens with short attention spans—but that’s hardly breaking news.

This is why we go completely bananas over Ebola or spend trillions to combat terrorism but more or less ignore global threats such as climate change or growing income inequality. Yet as noted futurist Andrew Zolli points out, the chances of any of us personally being affected by the former are minimal while just about every one of us will be affected by the latter.

I am thinking about these things as I stand at Año Nuevo State Park listening to docent and naturalist Jeff Phillips as he leads a small group of us on a Coastal Geology Tour. Geologic time, like climate change, is nearly impossible for us to get our heads around and really difficult to personalize. Unlike the story of a deranged gunman shooting up some mall, there is no familiar narrative to process into easily digestible units. However, Phillips is giving it a shot.

At the moment, we are standing on Cove Beach, a short hike down New Year’s Creek Trail from the park’s Marine Education Center. To the north, Año Nuevo Island lurks offshore like the fossilized back of some Jurassic marine predator. Phillips gestures out at the sparkling ocean beyond. The horizon line is roughly three miles from shore—that’s about as far as we can see with the naked eye from this elevation. Ten thousand years ago, however, during the last Ice Age, the coastline was another mile beyond that. This explains why archaeologists don’t find much evidence of the New World’s original inhabitants—most of these early settlements are submerged under a couple hundred meters of water.

Ours was a very different landscape in those days—and incredibly hostile. Columbian Mammoths, Saber-Toothed Cats, Dire Wolves and bears twice the size of modern-day grizzlies roamed the area—alongside camels and the ancestors of horses. Yet there is definitive proof that humans also existed at this time—right here where the state park exists today. Phillips crouches down and points into one of the many tiny caves that pock the marine terrace along the beach. Hidden in the cave is evidence of a 10,000-year-old hearth. The site is unexcavated, but the charcoal from the ancient fireplace has been carbon dated.

But what drew early man to this particular place? After all, it was four miles inland from the coast at that time.

Jewels and Tools

Over the course of the ensuing millennia, the planet warmed back up, the ice melted and the ocean eventually encroached upon the continent to its present-day location. The descendants of those first people at Año Nuevo were a band of Ohlone called the Quiroste. Like most coastal Native Californians, they were seasonal hunter-gatherers and only spent part of the year at the beach. In addition to food, Año Nuevo was an important source of two other very important resources—olivella shells and Monterey chert. A byproduct of a small, sand-dwelling snail, the shells were fashioned into jewelry and beads and traded widely for stuff the Quiroste wanted or needed. The chert is a sharp, tough, lithic material that could be fairly easily manufactured into edged tools and projectile points. It is impossible to overstate the importance of the latter. This stuff was vitally important to every aspect of the Quiroste’s lives. It was like finding a forest of Ginsu knives growing on the beach 5,000 years ago. As a result, Monterey chert has been discovered at archaeological sites up and down the coast—and Año Nuevo was one of the very few exposed sources.

Of course, the Quiroste’s treasure was a mariner’s worst nightmare. The reefs off the shore of Año Nuevo are also made of Monterey chert and it can slice through the hull of a ship with the same ease as it once butchered prehistoric meat. By the mid-1800s, Año Nuevo and Pigeon Point had a really bad reputation for sinking things into white-shark infested waters. But here’s where I get back to this idea of short- and long-term threats. As awful as it would be to have your arm torn off by a grizzly (more about that particular fate in next week’s column) or your ship eviscerated by razor-sharp reef, there is something far more dangerous lurking at Año Nuevo.

Here in California we live on a major time bomb—the San Andreas Fault System. Surprise! (Just kidding, you knew that.) What you may not know is that Año Nuevo State Park lies directly on top of one of the major faults within the San Andreas Fault System—the San Gregorio Fault Zone.

The San Gregorio-Hosgri Fault Zone branches off of the San Andreas fault zone up near Bolinas Lagoon and extends all the way down to Point Conception. No less than six different fault lines run through the state park. In fact, if you take the Coastal Geology Tour, your guide will probably show the same unsettling enthusiasm in pointing them out to you as Phillips is doing for us.

Nukes and Kooks

Believe it or not, back in 1969, PG&E decided it would be a good idea to build the largest nuclear power plant in California at El Jarro Point—about nine miles south of Año Nuevo (near Scott Creek). Their geologists surveyed the area and announced that it was a perfectly splendid place to construct nuclear reactors. Fortunately for us, a UCSC grad student named Jerry Weber happened to take a walk along Cove Beach at Año Nuevo State Park in 1973. A recent storm had eroded the marine terrace and revealed a fresh cut of 8,000- to 10,000-year-old deposits. Weber, who was working on his geology thesis under advisor Dr. Gary Griggs, knew a thing or two about seismological indicators and quickly identified the signs of not just one active fault, but “an incredibly complex nest of faults.”

According to Weber, the State of California classifies a fault as active if there has been surface displacement within the past 10,000 years. The definitions are far more rigorous for “critical facilities” such as a nuclear power plant. One episode of surface rupture in the past 40,000 years, or evidence of repeated movement within the past “several hundred thousand years,” can spell doom for a project. With the help of the USGS, Weber’s research quickly revealed that faults at Año Nuevo had been active as recently as when the first Californians were building fires in caves and hunting Columbian Mammoths with chert-pointed spears—around 10,000 years ago. In other words, Año Nuevo is seismogenic—it has been and will again be the site of major earthquakes. The maximum earthquake size is estimated to be between 7.25 and 7.75 Richter Magnitude. The Loma Prieta Earthquake, in comparison, was a 6.9.

Needless to say, Weber says this information resulted in some “really interesting interactions” with PG&E’s consultants. “PG&E,” Weber quips today, “had the best geologists money can buy.”

Eventually the evidence that Weber presented in collaboration with the USGS provoked enough public outcry to stop the project and also earn him a PhD. But hey, you can’t really blame PG&E’s geologists. It was 1969—the Summer of Love—they were just crazy kids caught up by the carefree climate of insane risk and naïve experimentation.

So, in a way, you can thank Jerry Weber for saving California from radioactive death. While the Loma Prieta earthquake of 1989 was centered further inland and probably wouldn’t have had an effect on an El Jarro Point facility, geologists discovered that the San Gregorio-Hosgri Fault passes by offshore—within about 500 feet of the proposed site. “Basically the equivalent of building on top of the thing,” Weber says.

Whew! That was close.

Risk and Reward

Not so fast. Unfortunately, as I mentioned earlier, the San Gregorio-Hosgri Fault doesn’t stop there. It continues meandering its potentially murderous way all the way down the coast to Avila Beach—the present site of the Diablo Canyon Nuclear Power, which PG&E began operating in 1985. Oh yeah, Diablo Canyon is also pretty close to the San Andreas Fault. So maybe radioactive death is in the cards for California after all. But don’t worry. If it makes you feel any better, Diablo Canyon is designed to withstand a 7.5 magnitude quake.

Today, Jerry Weber is retired after a 35-year career as a geology consultant. You can still find him occasionally wandering around Año Nuevo State Park—and even leading the Coastal Geology Tour. When he looks back on those days when PG&E was trying to build the plant at El Jarro Point, he shakes his head.

“It’s incredible how little we knew about what’s going on out there with the faults,” he says. “It was a real eye-opener about how huge and complex this fault system is. The problem is we have such short lives and it takes 300 to 400 years to get a good idea about the processes that operate on those systems.”

As our own Coastal Geology Tour wraps up and my little group parts ways, I wander up the beach to check the waves. Sure there’s a team of marine biologists tagging white sharks off of Ano Nuevo Island right now, but the wave is firing in all its October glory. I hurry back to my car to get my wetsuit and fins. After all, what’s the big deal about a shark severing me in two after learning I’ve narrowly escaped a radioactive holocaust?

About Año Nuevo State Park’s Coastal Geology Walk:
The next Coastal Geology Walk is at 1pm on Saturday, Nov. 1. Año Nuevo State Park is located on State Route 1, approximately 20 miles north of Santa Cruz and 35 miles south of Half Moon Bay. Año Nuevo is about a 1.5 hours' drive south of San Francisco.

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