Bernal Heights Summit

You are currently approaching one of the most geologically significant landmarks in San Francisco. The summit sits atop a foundation of radiolarian chert, a hard, red, sedimentary rock formed roughly one hundred and fifty million years ago when the Pacific and North American tectonic plates collided. This ancient, folded bedrock acts as a natural stabilizer. When the 1906 earthquake struck, the structures built directly onto this resilient chert suffered far less damage than buildings sitting on the city's softer, loose sediment. This stability is largely why the surrounding area became a haven for earthquake refugees who rebuilt their lives on the slopes of the hill.