Photo is courtesy of and © MultiRotorCam.com. Check out his stunning aerial videos.

One way to cope with the threat of earthquakes: poke fun at it with a t-shirt!

Linear For A Reason

There is a sign along I-280 that declares it as the World’s Most Beautiful Highway (see it here). While I-280 does not make Fox News’ list of the World’s 10 most beautiful Highways, I agree with the sign. I often commute on this highway and am always amazed at the rolling greenery and sparse development along this freeway that serves so many. One beautiful and very striking feature is a series of long, linear lakes that parallel I-280 for about 7 miles. Their shape is no coincidence. The main trace of the San Andreas Fault runs right under these lakes.

Map of the San Andreas Fault and other major faults in San Mateo County, California. Image adapted from USGS Open-File Report 2005-1127.

There are two bodies of water that clearly define the main trace of the San Andreas Fault, San Andreas Lake and the Crystal Springs Reservoir. Both were created in the late 1800’s by the Spring Valley Water Company to supply drinking water to San Francisco. The first dam, constructed in 1869, created San Andreas Lake which had been a small natural lake known as a sag pond. Sag ponds form along fault zones because the grinding of the rocks over millennia make the bedrock less permeable, allowing water to pond. However, these reservoirs were built long before anyone knew what a sag pond was or about the San Andreas Fault System and its impacts!

Crystal Springs Reservoir contains two dams. The first one was built in 1877 to create Upper Crystal Springs Reservoir and the second was built in 1888 to create Lower Crystal Springs Reservoir. The second dam, however, effectively impounds water from the watersheds of both lakes so the first dam became a causeway (today’s Highway 92) between the two lakes. In 1924, culverts were installed through this first dam to allow water to flow freely between the upper and lower reservoirs.

Water From the Sierra!

Beyond being clear harbingers of a major fault system these two lakes are also unique because most of the water they store doesn’t come from within their natural watersheds. They are the end of the line for water transported via the 167-mile Hetch Hetchy Aqueduct. Completed in 1934, the aqueduct moves water from the peaks of Yosemite National Park in the high Sierra, across the Central Valley and ends by putting water into Crystal Springs Reservoir at the site of the Pulgas Water Temple (click for a great video and history). The two lakes are connected by tunnels and pumps so water from Hetch Hetchy can be stored in Crystal Springs Reservoir or San Andreas Lake.

Map of the Hetch Hetchy Project which in 1934 began to deliver water 167 miles west to San Francisco. Map by Shannon1.

Dams Survive Two Big Quakes!

Built in the 19th century with no knowledge of the mighty fault beneath, and on top of some rather fractured bedrock, all three dams in this reservoir system survived the large magnitude 1906 San Francisco and 1989 Loma Prieta Earthquakes. The 1906 quake actively cut through Crystal Springs Reservoir, San Andreas Lake, and the stream valley that connects the two bodies of water. The oldest Upper Crystal Springs Dam (current Highway 92) was actually offset 8 feet (the west side went north) but, amazingly, held. The offset has been removed by repairs over the years. The Lower Crystal Springs Reservoir was undamaged even though the fault rupture was less than 1,000 feet away. Finally, at the San Andreas Dam there was 8 feet of movement immediately to the east of the dam, again with no compromise to the dam! The fact that these three dams survived so close to the 1906 rupture zone and then again survived the 1989 Loma Prieta Quake when they were all over 100 years makes these lakes even more incredible.

The causeway on highway 92 across Crystal Springs Reservoir. It was offset 8 feet (with the west side going north) buy the 1906 earthquake. Since then the causeway has been rebuilt and the offset can no longer be seen.

This monument along San Andreas Dam was installed in 1991 and marks the area that underwent 8 feet of displacement.

San Andrés Forgive Us Our Misspellings

Perhaps you have noted that San Andreas Lake has the same name of the fault I am making so much of? Again this is no coincidence! The San Andreas Fault takes its name from the very same lake. When the Spring Valley Water Company built the San Andreas Dam in 1869, the dam, reservoir and lake were called San Andrés. The name derives from the first Spaniards in Alta California. Gaspar de Portola’s expedition camped above present day San Andreas Lake on November 4th, 1769. Four years later on November 30th, 1773, several from the expedition returned to the site and named the area Cañada de San Andrés after the name of the saint whose feast day it was. The name became established and was seen on late 18th century Spanish maps of the area.

Corruption of the Spanish spelling seems to have started around the 1850s with the change from San Andrés to San Andreas. The accent on the e was intermittently (though often) used through the 1890s and even had occasional use from holdouts through the mid-1960s. The main switch seems to be due to University of California geology professor Andrew Cowper Lawson, who started calling the valley that drained San Mateo Creek the the San Andreas Valley in a published paper in 1893. He was a respected geologist and trained generations of students about what came to be called the San Andreas Rift Valley after the clear offsets from the 1906 quake.

Plaque above San Andreas Lake commemorating the camping spot of Gaspar de Portola’s expedition on November 4th, 1769.

Further Information

If you want to take a hike between San Andreas Lake and Crystal Springs Reservoir and see evidence of movement from the 1906 quake check out the book Geologic Trips: San Francisco and the Bay Area by Ted Konigsmark. He has a guide to where to hike and what to look for. The book, along with other great geologic tours can be found at his website Geologic Trips.

Women in bloomers and children in search of treasure once flocked to Pebble Beach to spend hours hunting for the best pieces of agate, opal, jasper, and carnelians polished by the waves to shiny perfection. Also known as Bean Hollow State Beach North, the beach is located along California’s scenic Highway 1, about 30 miles north of Santa Cruz and 17 miles south of Half Moon Bay. It was a famous tourist destination in the late 1800s and the place of failed dreams for a greedy local millionaire, dead-set on privatizing Pebble Beach.

The Ocean Shore Railroad & Pockets Full of Pebbles

The Ocean Shore Railroad was originally designed to connect Santa Cruz and San Francisco by rail. Building began in 1905 at both ends. Between the years of 1907 and 1920, passengers could catch this rail line starting in either town but a gap remained between Tunitas (south of Half Moon Bay) and Swanton (north of Davenport), with Pebble Beach and Pescadero solidly in this gap.

The town of Pescadero, three miles from Pebble Beach, still managed to have a thriving tourist industry: Visitors from San Francisco could take the train to Tunitas and then board the Stanley Steamer stage and finish their journey by stagecoach to reach Pescadero. (It’s not clear if folks from Santa Cruz had this option.) Swanton’s Hotel in Pescadero provided lodging for the travelers and transported folks by the wagonload to Pebble Beach everyday.

The writer of a report in the Alta California (May, 1867) describes the extreme popularity of the beach’s pebbles:

“The whole conversation at the [Swanton] hotel is pebbles. The house is full of them; one steps on them in the parlor or on the stairs; visitors carry them in their pockets and compare them at the breakfast table; they are, in fact, in everybody’s mouth! I verily believe they carry them to bed, and dream of pebbles all night …”

Rock Collecting in Bloomers

The writer also describes the “ludicrous” scene of folks in their finery (including many pairs of bloomers) sprawled on the piles of pebbles, their heads stuck in holes that they’d dug in their passionate search. It is said in one account that these collections could be found in all the upper class houses in San Francisco and along the coast. Today’s beachgoers are no longer allowed to collect the pebbles, but you can still lay face down on top of them (wearing your bloomers if you like) and look and touch to your heart’s delight.

Women in their bloomers at the beach in 1898. Original image is in the public domain.

“Coburn’s Folly” & The Gate Debate

A wealthy man named Loren Coburn owned most of Pescadero, including Pebble Beach. He had plans to build a hotel overlooking the beach and a town called “Coburnville.” According to the late local historian and 35-year San Mateo County resident, June Morrall, Coburn was an uncharitable millionaire who had few friends in the Pescadero community. In addition to his sour temperament, Coburn was accused of murdering a well-liked Pigeon Point wharf employee in a shootout. Coburn proved he was a most disagreeable fellow by putting up a locked gate on his property, barring the public from accessing their beloved Pebble Beach.

A group of locals were enraged by this greedy act and banded together to storm the gates. Morrall writes that “the mood was one of vengeance as Pinkham [County Roadmaster and the group’s leader] sized up the pine bridge planks, fastened with long wire spikes, that sealed the entrance. Methodically, the roadmaster slashed away at the offensive chains and padlocks and the gate opened.”

The Pebble Beach War

This started what was called “The Pebble Beach War.” Every time someone tore down Coburn’s barricades he would put them up again. Eventually Coburn charged his longtime adversary, local business-man Joe Levy, with a misdemeanor for taking part in breaking into his private road. Pescaderans finally pushed for the beach to be dedicated as a San Mateo County public park. The legislation passed in 1893 but it did not ensure that Coburn’s road be made public.

Loren Coburn’s Hotel and livery stables at Pebble Beach. Photo © California Views Collection. Used with permission.

Coburn continued to fight for private ownership of the land. Despite it now being a public park, he somehow managed to build his grand hotel above the beach that offered modern luxuries like hot water. He had hopes of large profits and huge success as there were still solid plans for the Ocean Shore Railroad to pass through Pebble Beach. These hopes and dreams never came to fruition, and it is said that the only person to stay overnight at Coburn’s hotel was the watchman.

The hotel’s failure was in small part due to the 1906 San Francisco earthquake which damaged much of the rail line. Funding for completing the tracks largely dried up soon after. The main barricade to success though was probably his widespread unpopularity. Supposedly, tales of the “gate debate” spread and slowed tourism to the area for a time. The fine folks of San Francisco had probably heard of Coburn’s selfish and inhospitable nature and decided to avoid the new hotel. The failed hotel burnt down in 1920 and is remembered as “Coburn’s Folly.”

An Uplifting Beach

Like most of the beaches in coastal California, the sea cliffs here were once loose sediments on the bottom of the ocean floor. The flat cliff tops that you can see in the opening video are part of the first marine terrace.

An example of marine terraces along the coast north of Santa Cruz. The numbers correspond to the generally accepted numbering of each terrace—from the first marine terrace (agricultural fields) to the fourth (highest set). Picture © Kenneth and Gabrielle Adelman, California Coastal Records Project www.Californiacoastline.org

If you go to Pebble Beach, keep an eye out for these wide, flat stairs, or marine terraces, rising out of the skyline as you drive along Highway 1. Each terrace is an ancient ocean floor that has since been slowly uplifted by large tectonic movements on the San Andreas Fault System. The higher the terrace, the older it is. The steep surfaces that separate each terrace are ancient beach cliffs eroded away by waves when sea level was high.

At Pebble Beach the modern sea cliffs are Quaternary in age, about 100,000 years in this case, and the sediments are beach sands or deposits from fairly near the paleo-shoreline.

Pebble Beach with Quaternary sandstones in the foreground.

Underwater Landslides of the Cretaceous

The flat beach surface, or “beach platform” is totally different than the sea cliffs. Those rocks are late Cretaceous in age, or 60 to 100 million years old, and show the story of much tectonic activity through their 63 degree tilt. These tilted sediments were originally deposited far from their paleo-shoreline in water about a mile deep. What’s odd is that normally in such deep water the sediments are fine-grained silts and muds, but these sediments are mostly coarse pebbles!

Why Are There Pebbles on Pebble Beach?

So how did the pebbles end up in deep water? They were essentially the deposits of repeated underwater landslides called turbidity currents. Turbidity currents are plumes of sediment (dense gravel, sand and mud) that rush downslope, often triggered by an earthquake. They carve out everything in their path and carry the debris for long distances. They usually set up a channel that transports sediments out into deep water over and over again. Sometimes it’s a mix of really coarse stuff, sometimes its finer grained muddy stuff. This is essentially what is happening right now south of here in Monterey Bay Submarine Canyon. Once these deposits turn into rock, they are called turbidites. The beach platform at this beach is composed of turbidites. The pebbles on the beach and in the younger sea cliffs are reworked and recycled from these Cretaceous turbidites. They likely get stuck here due to the deeply convex shape of the beach.

The multi-color pebbles of Pebble Beach. Photo courtesy of John Kim. (June 2009)

Tafoni: Rock Art Created by Salt & Air

Looking south across the parking lot of the official Pebble Beach is another section of coastline covered in an amazing display of tafoni or honeycomb weathered rock. The sandstone here looks like abstract hunks of swiss cheese—it’s filled with holes and undulates along the beach in subtle waves and dramatic peaks of latticed stone. These “honeycombs” in the rocks are caused by the salty air wearing away weaker sections of the rock. Because this is an inter-tidal area, the rocks are subject to wetting and drying cycles as well as wave action. Once a small hole forms, it accumulates ocean water and other debris that accelerates the erosion process and expands the cavity, creating what looks like a honeycomb.

Tafoni or “honeycomb” weathering at Pebble Beach. Photo courtesy of Dawn Endico. (Dec 2011) 

What Could Have Been

Pebble Beach may not offer seaside accommodations as it did over one hundred years ago, but it still offers an abundance of geologic wonders as well as tide pools filled with fascinating invertebrates and coastlines teaming with marine life like harbor seals, Brandt’s cormorants, and whales. In fact, we’re lucky that this historically popular tourist destination was never developed the way Loren Coburn would have liked. Instead of “Coburnville” and private roads guarded by locked gates, we have a beautiful state beach for everyone to enjoy.

Take the Self-Guided Mobile Tour

This piece is part of the North Coast Tour. Download the free app with many tours of the Santa Cruz area and beyond.

Concrete Ships: Early Days

The oldest known concrete ship was a dingy built in southern France by Joseph Louis Lambot in 1848 and was featured in the 1855 World’s Fair in France. By 1890 there were concrete barges and small ships being built by the Italian engineer, Carlo Gabellini. Numerous small concrete boats were built in the U.K in the 1910s. The first ocean-going concrete ship was launched from Norway on August 2, 1917 and was built by N.K. Fougner. The 84-foot-long ship, named Namsenfjord, was a great success, and several more small concrete vessels were built.

In 1917 the United States entered WWI and needed to build ships at a time when steel was scarce. The US government invited Fougner to head a study into the feasibility of concrete ships. In April of 1917 President Woodrow Wilson approved the Emergency Fleet program, which approved the construction of 24 concrete ships for the war.

Seeing a business opportunity, W. Leslie Comyn formed the San Francisco Ship Building Company (in Oakland, California) and began constructing concrete ships. Their first ship, the SS Faith, was launched March 18, 1918. They also built the SS Palo Alto for the US Government, which launched May 29, 1918.

Photograph of the SS Faith, the first ship built of concrete in the United States, soon after launch in 1918. Photo via Wikimedia Commons. Originally in Popular Mechanics Magazine, July 1918.

Too Late for the Party

WWI ended on November 11, 1918. Only 12 ships were under construction and none of them had been launched and commissioned (actually put into service) in time to be of service in WWI. The SS Palo Alto, although launched, was not commissioned until October 20, 1920. It had its first and only voyage under its own (steam) power on January 2, 1921. The same year it was towed to Benicia, California and mothballed.

In 1930 the SS Palo Alto was towed to Seacliff State Beach by the Seacliff Amusement Corporation and sunk a few feet into the water. A dance floor, swimming pool, and a café were added transforming the SS Palo Alto into an amusement ship for two years until, with the help of the Great Depression, the company went bankrupt. Shortly thereafter, the ship cracked at the midsection during a winter storm. In 1936 the State of California purchased the ship for $1 and made it part of Seacliff State Beach. The foredeck of the ship was closed to the public in 1958, but the afterdeck is closest to the beach and remained open until at least the 1970s and possibly the mid-1980s, when access was completely closed off for safety reasons. Today she serves as an artificial reef for marine life.

The SS Palo Alto at sunset, December 31, 2007. Photo by Nicholas Mitchell.

In spring of 2005 oil found on wildlife nearly two years earlier was traced back to the ship. A large cleanup project was started at a cost of $1.7 million. No oil is known to have spilled into the ocean. Wildlife experts think the birds came into contact with oil by diving into the cracked hull while fishing.

Concrete Ships: Less than Ideal

The basic problem with concrete ships is that they require a very thick hull to be as strong as a steel ship. Ships built for WWI had hulls up to 6 inches thick and required a lot of fuel to move around. Since wet concrete sags, they are also tricky to build. Perhaps more importantly for warships, they sink quickly if the hull is breached. The sailors of WWI often called them “floating tombstones” and generally did not like to serve on them.

When WWII came about, steel was once again in short supply and the US Government again authorized the construction of 24 concrete ships as well as barges for transporting supplies. Construction began in 1943. Thanks to innovations in cement mixing and materials, this round of ships was much stronger than the previous fleet. Nevertheless, after the war, the concrete ships were generally gotten rid of — quickly. Nine were sunk in shallow water in Chesapeake Bay off the coast of Kiptopeke Beach, Virginia in 1948 to create a breakwater for the local ferries. For a video explaining the history of this breakwater, click here. Nine more ships were used to create a floating breakwater on the Malaspina Strait in the city of Powell River in British Columbia, Canada.

Sunset over two of the WWII era ships sunk in shallow water off of Kiptopeke Beach, Virginia. Photo by VAStateParksStaff.

Though some small boats are made of concrete today, WWII was the end of large-scale concrete ship building.

Take the Self-Guided Mobile Tour

Find out more history of the S.S Palo Alto and Seacliff State Beach as part of our Santa Cruz Marine Protected Areas Beaches Tour made possible by the Santa Cruz Collaborative with support from the California Marine Sanctuary Foundation and the Resources Legacy Fund. Download the free app with many tours of the Santa Cruz area and beyond.

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1. Sources Used

   • A brief History of Concrete Ships. ConcreteShips.org Website. http://www.concreteships.org/history/
   • Floating Tombstones. The UnMuseum.Org Website. http://www.unmuseum.org/concrete.htm
   • Kiptopeke’s Concrete Ships; A Long Journey to Obscurity.Abandoned Country Website. http://www.abandonedcountry.com/2013/05/06/kiptopekes-concrete-ships-a-long-journey-to-obscurity/
   • Personal communication with Lorena DeWild, Santa Cruz County Resident, January, 22, 2014.
   • Personal communication with Sandy Lydon, Historian Emeritus, Cabrillo College, Aptos, January, 22, 2014.
   • Ships of concrete long sunk off the Eastern Shore. Diane Tennant, The Virginian-Pilot. October 9, 2011. http://hamptonroads.com/2011/10/ships-concrete-long-sunk-eastern-shore#
   • SS Palo Alto. Wikipedia. http://en.wikipedia.org/wiki/SS_Palo_Alto
   • What's the SS Palo Alto Really Made of? Sandy Lydon's Hooey History. http://www.sandylydon.com/hoo_1.html

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