Devil's Slide

Growing up in the cozy town of Moss Beach, highway 1 felt to me like a tether: the fragile, thin line that connected our quiet community to the bustling Bay Area metropolis on the other side of the hill. When rockslides cut that tether, a surreal silence would settle in as usually-constant stream of through traffic suddenly disappeared.

Devil's Slide hiking bicycle walking tours Half Moon Bay Linda Mar Pacifica coastsideFollowing that vein Northward towards Daly City and San Francisco meant crossing the treacherous, cliff-clinging section of highway known as Devil’s Slide. From the backseat of the family car, I could barely see the top of the crumbling cliffs towering over us. Often, the coastal fog would be creeping its way upward toward the sunny peaks above. The place looked magical, and I always wanted to get out of the car and explore that mysterious and infamous piece of highway.

Unfortunately, the persistent traffic and lack of highway shoulders prevented us from ever stopping.

Before the highway was built, the Devil’s Slide roadbed was constructed as a part of the 1905 Ocean Shore Railroad project, an ambitious attempt to connect San Francisco to Santa Cruz with a scenic rail line. The foothills of San Pedro and Montara Mountain were too steep for the passenger locomotives of that time to handle, and a coastal train ride was the pitched draw for tourism, so Ocean Shore decided to grade a rairoad bed right into the side of the sheer cliffs between the modern towns of Linda Mar and Montara.

Grading Devil’s Slide was tough. Engineers expected most of the earth there to be similar to the silty, sandy stuff they'd worked encountered nearby. The project started with a loose type of shale that was relatively easy to move through.

About halfway across the cliffs, they hit solid granite. Getting through granite was no easy task, and required the consultation of mining engineers. In post-gold-rush San Francisco, there was no shortage of such expertise. The task would require then-state-of-the-art pneumatic rock drilling technology and high explosives. The unexpected cost of this equipment, combined with devastating losses in the 1906 earthquake, was the beginning of the ill-fated Ocean Shore Railroad’s unending financial problems.

Those grueling days grading the railroad bed would earn the site its name, as the point where shale turned to granite is actually an unstable fault line. Giant boulders and rocks would come down unpredictably on engineering crews as they worked on and moved equipment through that unstable area.Devil's Slide cliffs Half Moon Bay Coastside Tours walking hiking bicycle

This was only the beginning of the trouble that Devil’s Slide presented for the Ocean Shore Railroad Company. When they began running passenger trains, the infamous rock slides would often delay and sometimes cancel trips. Constant rail maintenance was required to keep the tracks safe for use. The costs from this single stretch of railroad are cited as one of the fatal problems that pushed the company to failure.

Once the railroad company finally halted service in 1921, the roadbed lay unused for some years until highway one was constructed in the 1930’s. Construction of route 1 brought more blasting as highway engineers widened the passage for two lanes of traffic.

As soon as highway traffic began moving through Devil’s Slide, trouble returned. Cars would occasionally topple from that stretch of highway, and earth movements and landslides were a constant threat for the safety of motorists and the reliability of that passage. In 1995, the road was closed for several months when a part of the highway cracked as pieces of the cliff crumbled into the sea. That closure turned my father's usual twenty-minute commute to work into almost an hour, forcing him to head south to highway 92 to cross the coastal mountains.

In response, local municipalities campaigned for funding the construction of a tunnel that would bypass the slide. I remember the bright yellow pro-tunnel bumper stickers and the local enthusiasm for the project, all before my tenth birthday.

It took almost twenty years after voters approved the project to open the tunnels.

AngieAs an afterthought, a coalition of historic and nature enthusiast organizations pushed to reopen Devil’s Slide as a point of interest for tourists to come learn about that fascinating place. It was a unique opportunity to open the geology, biology, history and beauty of that once-busy stretch of highway to visitors.

The highway is still in excellent condition, providing a wonderful passage for cyclists and hikers who want to explore it.

It’s also created an opportunity for me to fulfill that childhood fantasy of mine, to walk around and explore that area without traffic. Having seen it constantly full of aggressive bay area drivers for more than twenty years of my young life, walking it today in all its tranquility is, for me, an eerie and fascinating experience.

Starting the three-mile walk from the south end, as I do, you will see the towering granite cliffs that engineers spent so much time cutting through. The quartz content of this granite gives it a sparkling appearance.

Usually, you’ll spot a biologist sitting on the other side of the ocean-side concrete barrier within a quarter mile of the parking lot. Peering through binoculars or scribbling away in a notebook, they’re studying an important colony of the endangered Common Murre that has an important colony on a tiny rock island, dubbed “Devil’s Slide Rock,” beneath the slide.Devil's Slide Rock Common Murre colony haven rehabilitation project decoy Half Moon Bay Coastside Tours bird watching

This colony shrank from 3,000 birds to just a handful of individuals in the 1980s, due to a number of environmental threats including an oil spill and net fishing activity in the area. After an extensive rehabilitation project where biologists placed mirrors and decoys (fake birds) to attract new individuals to join the Devil’s Slide Rock colony, it steadily regrew almost to its original size.

Once the highway closed, the sensitive Common Murre colony was disturbed again – they had become accustomed to the constant highway noise, and when it stopped, they apparently felt threatened. For that reason, biologists have been anxiously monitoring the health of the colony.

From atop these cliffs, one can stop and and catch a glimpse of the rock's rare inhabitants through binoculars.

Hundreds of feet and almost directly above Devil’s Slide rock is an abandoned WWII observation bunker, one of many that were built all along the California coast to watch for a potential Japanese invasion. This installation was also a part of a triangulation-targeting system that could locate ships around the Golden Gate with pinpoint accuracy. Though currently inaccessible, one can admire the concrete stairway that carried American sentries up that granite outcropping. At its top is a crumbling steel tower, now dwarfed by a tall and proud Monterey Cypress tree.

Continuing northward, one will encounter a sudden dip in the highway accompanied by a visible change in the character of the cliff’s rocks. This is the point where granite turns to shale, or vise-versa if you are heading south. That dip was not the doing of the Ocean Shore Railroad engineers; it is the result of over a century of erosion along that dividing line. This is the infamous location of countless slides and the place that earned this stretch its nickname.

geometric rock shapes Devil's Slide geology Half Moon Bay Coastside ToursFrom here, you hit a steady uphill climb, where I often catch a glimpse of soaring Red-tailed hawks, turkey vultures, or the occasional Peregrine Falcon riding the updraft far above.

The top of this hill, the highest point along this scenic road, offers spectacular views of the Pacific Ocean. On a perfectly clear day, the Farallone Islands somehow appear closer than they are. Looking upward, the shale appears in odd cube-shaped formations, appearing in sizes between that of a die and that of a Rubik's cube, and every size in between. The geometric consistency of those rock formations is mesmorizing.

Although I always take this trip on foot, I can see why it’s such a popular spot for cyclists. There is no bike lane to get cylists to the Devil's Slide trail, but one can easily tote a bike on a bike rack and park at either trailhead. From there, the road surface is perfect for a brisk 6 mile out-and-back road bike trip. This ride offers a moderately-graded section for a short climb up and a chance to enjoy the breathtaking views on the way down.

On foot or on wheels, Devil’s Slide is an excellent point of interest for those looking to learn more about the history of our coastal community and its connection with the greater San Francisco Bay Area. For wildlife enthusiasts, especially those interested in our coastal bird species, it’s a wonderful opportunity to find some rare species. Whatever your reason is for visiting our community, I highly recommend checking out Devil’s Slide.

Thanks for reading and we’ll see you here on the sunny coast!

-Michael Klear, Half Moon Bay Coastside Tours Guide and Blogger


Half Moon Bay Coastside Tours specializes in making your trip to the San Mateo County coast the best it can be. Contact us for more information on corporate group tours, guided hiking or bike tours, team-building activities, wine tasting, and much more! Whatever it is that brings you to our community, we're happy to help you make it happen.


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