Indian Rock, an outcropping of Northbrae rhyolite in the Berkeley Hills, is an ancient volcanic remnant that reflects the area’s complex geological past. Native Ohlone communities gathered at these rocks and ground acorns into meal with stone pestles, gradually wearing bowl-like depressions into the surface. In the early 20th century, the Mason-McDuffie Real Estate Company developed the surrounding Northbrae subdivision, and in 1917 donated park parcels around five rock formations, including Indian Rock, to the City of Berkeley. During the 1930s, Indian Rock and nearby Cragmont Rock became practice grounds for Berkeley mountaineering enthusiasts developing new techniques that revolutionized the sport, and the climbers here included the young Berkeley native and environmentalist David Brower.
