MacKerricher State Park · Fort Bragg, California
A 61-year mistake. A 60-year correction.
Nobody designed this beach. For 61 years, the city threw its garbage off the cliffs.
Fort Bragg opened its first cliff-top dump in 1906, on the bluffs behind the Union Lumber Company. Household waste, bottles, appliances, batteries, and eventually whole cars went over the edge. When the pile got too large to manage, residents lit it on fire — sometimes with Molotov cocktails — to reduce the volume. When the first site filled in 1943, the town simply moved the dump a few hundred metres north. When that filled in 1949, it moved again, to the cove now called Glass Beach. Dumping ended there in 1967 when the State Water Resources Control Board shut it down.
What the ocean did next was slow, stupid, and beautiful. Sixty years of winter storms battered the debris against the Franciscan Complex bedrock. Metal rusted into the reef. Ceramics broke, then broke smaller, then disappeared. Everything organic rotted. Plastic — mostly — got picked out by volunteers across multiple clean-ups. Only the glass, indestructible at the scale of a single human lifetime, kept tumbling. Edges dulled. Surfaces frosted under hydrofluoric attack from calcareous algae and sand abrasion. Shards became pebbles. Pebbles became gems.
The private owner spent five years from 1998 onward working with the California Coastal Conservancy on remediation, and in October 2002, California State Parks bought the 38-acre parcel and folded it into MacKerricher State Park. By then the beach was, improbably, one of the most photographed coastlines on the west coast.
Every colour on the beach is a piece of industrial chemistry. The rarest pieces tell you which decade they came from.
Source: Beer bottles, wine bottles, 7-Up (until 1950s).
Chemistry: Soda-lime glass coloured by iron oxide and chromium. Cheap to produce, nearly universal for bottling before clear glass took over in the 1960s.
Most of what you see at Glass Beach is this.
Balachander Palaniappa · Commons · CC BY-SA 4.0
Source: Whiskey and medicine bottles. Post-Prohibition beer bottles.
Chemistry: Iron, sulphur, and carbon added to the melt. The colour protects contents from UV light — the reason beer still comes in brown bottles today.
Rachel C (curlsdiva on Flickr) · Commons · CC BY 2.0
Source: Milk bottles, jars, the second half of the 20th century.
Chemistry: Pure soda-lime glass. The most modern colour on the beach; younger pieces still have sharper edges.
Paul VanDerWerf · Commons · CC BY 2.0
Source: Clear glass made before 1915 that contained manganese as a decolouriser.
Chemistry: Manganese(II) inside the glass absorbs UV over decades and shifts to manganese(III), which is purple. The older the clear piece, the deeper the tint.
Holds a date stamp: pre-1915 manganese clarifier was phased out during WWI when Germany cut off supply.
Source: Milk of Magnesia bottles, Vicks VapoRub jars, Noxzema, Bromo-Seltzer.
Chemistry: Cobalt oxide — expensive enough that it was only used for specific pharmaceutical and cosmetic packaging. Colour survives in seawater indefinitely.
Swampyank · Commons · CC BY-SA 3.0
Source: Automobile tail-light lenses. Schlitz beer (briefly). Avon collectibles.
Chemistry: Gold chloride or selenium-cadmium compounds — prohibitively expensive, almost never used for bottles. A single red piece is a collector's find.
Fort Bragg regulars say they know a serious visitor by which pocket they reach for when they spot red.
Swampyank · Commons · CC BY-SA 3.0
Source: Early-20th-century Ball and Mason canning jars. Soda siphons.
Chemistry: Naturally-occurring iron impurities in older glass sand. Modern glass is too clean to produce it.
Balachander Palaniappa · Commons · CC BY-SA 4.0
Source: Almost nothing. Art glass. Vintage automobile fog-lamps. Rare collectibles.
Chemistry: Selenium-cadmium compounds, or uranium glass. Orange glass was barely manufactured in any commercial quantity. Finding a piece is the rarest outcome of a day at Glass Beach.
Source: Pre-1900 wine and gin bottles, occasionally ink bottles.
Chemistry: Actually a very dense olive green. Hold a piece to the sun and it's translucent. The weight and apparent opacity tell you it's old — 19th century.
Tomcat Ranger · Commons · CC BY-SA 4.0
Rarity rankings follow the collector consensus documented by the International Sea Glass Association and reproduced at the Sea Glass Museum. Chemistry notes synthesised from the Corning Museum of Glass' primers on historical soda-lime and cobalt-doped glass.
Strip away the tumbled bottles and the story underneath is a lot older than California.
Glass Beach sits on the Franciscan Complex, a chaotic mélange of graywacke sandstone, shale, chert, and blueschist scraped off the Pacific Plate as it subducted under North America during the late Mesozoic — roughly 150 to 65 million years ago. Graywacke is the grey-green rock you see exposed at low tide: quartz and feldspar grains cemented in a muddy matrix, metamorphosed just enough to be hard but not enough to lose its sedimentary layering.
The Mendocino coast is rising faster than the ocean, so the shoreline climbs in terraces. The platform Glass Beach sits on was underwater about 125,000 years ago; another terrace above it is twice as old. The uplift that produces this staircase is the same tectonic setting that built the Coast Ranges — you can drive east from Fort Bragg and see the Franciscan Complex outcropping all the way to the Central Valley.
Without the dumping, the cove would be a conventional Northern California beach: cold, foggy, quartz-feldspar-lithic grey sand mixed with pebbles of graywacke and chert. In fact, as the glass slowly depletes, it is becoming that beach again.
Every visitor who pockets one piece is removing something that will not be replaced in any reasonable human timescale.
No one is dumping bottles any more — that's the whole point of the 1967 closure. The beach has a finite stock of glass and a rate of removal. Longtime Fort Bragg residents and park rangers all describe the same decline over the past twenty years, and the 2010s saw serious internal debate at California State Parks about whether to replenish the glass artificially. Nothing came of it. Replenishment would, correctly, be inauthentic — and expensive.
So the glass goes. Visitors take it. Storms grind it finer. Ocean chemistry does the rest. The most-scavenged cove (Site 3) has visibly less glass now than in photographs from 2010.
Taking sea glass from MacKerricher State Park is a misdemeanour under California State Parks regulations and Fort Bragg city ordinance. The penalty caps at $1,000 and 90 days in jail. Local rangers have become more willing to cite in the past decade.
The famous cove is Site 3, the last and largest. If you walk south along the headland trail you'll find the other two, less crowded and — on Site 1, specifically — with the oldest glass in the system.
Behind the Union Lumber Company, first opened as an official water dump. Thirty-seven years of bottles, cans, and burn-pile residue. Most heavily weathered, so pieces here are rounder, smaller, and with the oldest date provenance — the highest chance of pre-1915 sun-purpled amethyst.
Active for six years only, then closed when it filled. The least-photographed of the three. Tide pools here expose tidal-pool faults in the Franciscan graywacke; a good spot if you care as much about the rock as the glass.
The one everyone means. Eighteen years of dumping, including the post-war consumer-goods boom — the blue Milk of Magnesia era. Also the cove where visitor pressure has been concentrated, and where depletion is most visible.
Fort Bragg is the most famous. It is not unique.
A former Soviet bottle-and-porcelain dump, closed post-1991. Vodka bottles in every shade of green; enough tumbled porcelain to produce a speckled mosaic. Visitors removed glass so aggressively in the 2010s that Russian regional authorities restricted beach access.
A working industrial site — neighbouring the Hanapepe oil depot and former dump — with a smaller, denser concentration than Fort Bragg. Very little blue or red here; mostly green and brown.
Less well-known. The result of a glass-bottle factory that dumped production scrap in the early 20th century. Pieces are thicker — glass blanks rather than finished bottles. Geology is similar to Fort Bragg: Franciscan mélange under uplifted marine terraces.
The Victorian Seaham Bottleworks dumped slag and off-cuts into the North Sea from 1850 to 1921. The result is called ‘end-of-day glass’ by UK collectors — multi-coloured, sometimes three colours in one piece, from the last melt of the shift.
This is not a swimming beach. It's a 45-minute stop that will haunt you for a week.
Don't take any. Taking sea glass is a misdemeanour — up to $1,000 fine, up to 90 days in jail. The beach exists because the city stopped dumping; it continues to exist only if visitors stop pocketing. Photograph it. Stand on the bluff at golden hour and look at a million rounded bottles. Walk away.
Site dates and closure facts: Wikipedia: Glass Beach (Fort Bragg, California), cross-referenced with California State Parks' MacKerricher page and the Mendocino Land Trust.
Franciscan Complex description from the Geosciences LibreTexts chapter on the Coast Ranges and USGS open-file reports on the Mendocino County marine terraces.
Cobalt, manganese, selenium-cadmium, and gold-chloride colourants drawn from Corning Museum of Glass teaching materials and the International Sea Glass Association's collector guide.
Collection prohibition and penalties from California State Parks regulations for MacKerricher State Park and Fort Bragg Municipal Code enforcement.
Cass Forrington's founding story from the museum's own site and a 2022 profile in The Epoch Times.
All imagery linked from Wikimedia Commons under its original licence. Attribution visible on every image. No photos are re-hosted.
Last updated 2026-04-30. Corrections and primary sources welcome — this page improves with expertise from collectors, park staff, and geologists who know the cove better than we do.