Rodeo Beach is a pebbly beach in the Golden Gate National Recreation Area, about two miles west of the Golden Gate Bridge. It sits below Battery Townsley, between Fort Cronkhite and Rodeo Lagoon, and is popular with surfers.
Why the pebbles are colorful
The National Park Service says the beach formed about 5,000 years ago, when the rise in sea level slowed after the last glacial period. The sandy barrier dammed an old stream valley and created Rodeo Lagoon. Strong waves and currents left the coarse pebbles you see today.
Most of the pebbles are radiolarian chert, the most common rock in the Marin Headlands. Small amounts of iron oxidize in different ways and give the pebbles shades of green, yellow, red and black. Look all you like, but the park asks you not to take them home.
The lagoon
For much of the year the lagoon is cut off from the ocean, according to Wikipedia. The park service warns that rising seas could wash over the barrier beach. Without it, the lagoon would turn much saltier, which would threaten rare species that live there, including the tidewater goby and the California red-legged frog.
Trails and visiting
- Hikes: Park on Bunker Road near the Marine Mammal Center and take Old Bunker Road to the Coastal Trail and Battery Townsley. A full loop on the Coastal, Wolf Ridge and Miwok trails takes about half a day.
- Facilities: Entry and parking are free. There are wheelchair-accessible restrooms, showers, picnic tables and barbecues.
- Dogs: Dogs are allowed but must be on leash or under voice control.
Wikipedia notes that in November 2007, oil from the Cosco Busan spill washed up here and closed the beach for several weeks.