Round Top, an extinct volcano in the Berkeley Hills east of Oakland, is the central feature of Sibley Volcanic Regional Preserve and one of the Bay Area’s clearest remnants of ancient volcanism. Volcanic activity here began about 10.2 million years ago and lasted for more than a million years, leaving two main vents, one beneath today’s Lawrence Berkeley National Laboratory and one at Round Top. The Round Top vent later tilted and collapsed sideways, preserving evidence of the geological forces that shaped the hills. The surrounding park, established in 1936 and renamed in 1958 for Robert Sibley, protects and interprets this volcanic landscape.

Oakland, California · USA