Jasper Ridge is bounded by San Francisquito Creek, Corte Madera Creek, and Los Trancos Creek, though the preserve occupies only the northwestern half of the ridge. The hilly mass runs about ten kilometers from northwest to southeast and half that in width. The rocks tell a deep story: graywacke sandstone from the Franciscan formation dates to 138 million years ago. Greenstone, chert, serpentinite, and sandstone all surface here, each a chapter in the tectonic history of the Pacific margin. Ohlone people once ground acorns in mortars carved into the bedrock -- stone pestles have been found at the preserve, connecting its geological deep time to its more recent human past.

The preserve encompasses Searsville Lake, actually a reservoir, and the upper reaches of San Francisquito Creek along with its Corte Madera Creek and Bear Creek tributaries. Within this relatively compact area, the landscape shifts from coast redwood groves to chaparral to annual grasslands. The Global Change Experiment, one of the preserve's signature research programs, studies how California's annual grasslands respond to elevated atmospheric CO2, temperature changes, altered precipitation patterns, and increased nitrogen deposition. Researchers track Argentine ants, an invasive species that has displaced native ant populations across California. A monitoring station near the lake records bat echolocation calls at night, building a picture of the nocturnal ecosystem that most visitors never see.

In 1922, botanist William Skinner Cooper argued that Jasper Ridge was historically chaparral -- dense, woody shrubland -- and had been cleared in the nineteenth century to create open grasslands dominated by Eurasian wild oats. That transformation, typical of California's coastal hills, means the preserve's current landscape is itself an artifact of human alteration. The grasslands are now the focus of some of the most important climate research in the state. Located just south of Sand Hill Road and west of Interstate 280, the preserve sits within minutes of the venture capital offices and tech campuses that define modern Silicon Valley. That proximity makes it something rare: a place where deep geological time and cutting-edge ecological science coexist a short drive from the most future-obsessed region on Earth.