Collecting Ancient Rocks in Bloomers at Pescadero’s Pebble Beach

Many thanks to Barry Blanchard for permission to use this video.

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.
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 Pebble Beach Hotel and livery stables. Photo from the California Views Collection. Used with permission..
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.

This aerial photo taken about 3.5 miles north west of Western Drive on Highway 1 shows four marine terraces. 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.orgView looking west from the Old Cove Trail at  Wilder Ranch.
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

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 some tafoni in the Quaternary sandstone.
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)
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 cheeseit’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 at Pebble Beach, Dec 2011. Photo by Dawn Endico courtesy Wikimedia Commons.
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.


Go to Mobile Ranger Guides in the Apple App Store
Go to Mobile Ranger Guides in the Google Play Store
  1. Sources Used

    • South from San Francisco: The Life Story of San Mateo County by Frank M. Stanger. 1963. San Mateo County Historical Association.
    • History of Pescadero, California. From: The Story of San Mateo County, California. Roy W. Cloud. S.J. Clarke Publishing Company. 1928.
    • Half Moon Bay Memories: The Coastside’s Colorful Past Paperback. Jun Morrall. 1978.
    • Pescadero Memories: The Battle Over Pretty Pebbles at Pescadero. June Morrall. Posted on Jan 17, 2008. and
    • Geological Outings Around the Bay: Pebble Beach. Quest Website. Andrew Alden. March 3, 2011.
    • Bean Hollow State Beach, Pebble Beach. Coastside State Parks Website.
    • What is a turbidity current? NOAA Website.
    • Geology of the Marin Headlands and the Half Moon Bay coast. Saturday, May 19, 2001 California Rocks! Field Trip Guide. Instructor: Mary Leech GEO 116, Continuing Studies Stanford University.
    • The Geology from Santa Cruz to Point Año Nuevo—The San Gregorio Fault Zone and Pleistocene marine terraces. By Gerald Webber and Alan Allwardt. In: Stoffer PW, Gordon LC, eds. Geology and natural history of the San Francisco Bay Area: a field-trip guidebook: 2001 Fall Field Conference, National Association of Geology Teachers, Far Western Section: September 14-16. USGS Bulletin 2188; 2001:194.
    • Canyon Processes. Monterey Bay Aquarium Research Institute Website.
    • Our Ocean Backyard: Grand canyons on the seafloor. Gary Griggs. Santa Cruz Sentinel. November 21, 2009.
    • Our Ocean Backyard: Submarine Canyons: Going Deeper. Gary Griggs. Santa Cruz Sentinel. December 19, 2009.
    • Our Ocean Backyard: Why Monterey Submarine Canyon? Gary Griggs. Santa Cruz Sentinel. January 2, 2010.

About The Author

Molly Lautamo is a content strategist and writer in Santa Cruz, California. She loves exploring and researching her surroundings and then writing about her discoveries to inspire others to get out and explore too. You can check out more of Molly's writing at

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  1. Helen

    Hello, thanks for this great page. I live in Santa Cruz, was reading in the old newspapers about Pescadero and Loren Coburn when I came upon an 1897 article titled ” Pescadero’s Mysterious Beach of Shining Pebbles” and have included the link here (below). Please take a look, as it really explains how folks in the late 1800s enjoyed this marvelous beach!
    Link to article ~
    Link to the California Digital Newspaper Collection from UC Riverside:
    (Hint: use quotation marks when using Search.)

  2. Helen

    And here is a great 1896 article about Loren Coburn’s hotel – already referred to as “Coburn’s Folly”. Interesting how the watchman guarded the hotel from being set on fire, yet it burned down in 1920. Coburn had by then passed away.
    I have long been reading about his hold on that entire area. He had a chute (for loading ships) at Pigeon Point and was accused of murder there in 1875.
    Link regarding hotel:


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