These days, crowds of matriculating freshmen are being led by docents around the iconic campus of Stanford University. Many prestigious schools feature stone buildings, but the warm sandstone of Stanford's historic core is special. The stone has a Bay Area source.

The Bay Area's quarries are good for crushed stone, but not dimension stone. Generally, the rock around here has been shaken and folded so thoroughly that it's hard work to find decent blocks without fractures or alteration. We have some marble and limestone, but it's suitable only for making cement. And we have some granite, but for usable stuff in commercial quantities builders look east to the Sierra Nevada or out of state. The exception is the golden sandstone formerly quarried in the Santa Teresa Hills, south of San Jose.

The Santa Teresa Hills are a little outlier of the Santa Cruz Mountains that almost plug the south end of the Santa Clara Valley. Route 85 passes north of them and the Almaden Expressway runs to their south. Here they are in Google Maps.

Their rocks are largely the typical Bay Area rocks that builders spurn—Franciscan melange and metavolcanic rocks of the Coast Range Ophiolite—but the spine of the western end of the hills is made of a much younger, well-sorted sandstone of Eocene age, about 35 million years old. It's labeled "Tls" in this excerpt from the San Jose Quadrangle geologic map. The same rock underlies the peak of Loma Prieta and the crest of the Sierra Azul, across the intervening New Almaden block.

stanstonegeomap — Units Tls and Tcm (Tertiary rocks of Loma Chiquita Ridge and Mount Chuar) belong to the Sierra Azul block; the surrounding serpentinite (Jsp) and melange (fm) and basaltic lava (fpv) are much older and belong to the New Almaden block (lower left). Units marked "Q" are sediments.

You can visit the source by taking Camden Avenue east from the Almaden Expressway. Then turn left on Graystone Lane, where starting in the 1880s the Greystone Quarry shipped stone direct to Stanford from Leland Stanford's private rail spur. Just across Alamitos Creek is this old stone shed dating from around 1875, with an E Clampus Vitus sign telling its history. On the geologic map it's just under the "Tls" label.

stanford-stone-hut — All photos by Andrew Alden

The scars of the quarry itself, which closed in 1906, are long gone, but in many places along the hill you can spot the sandstone cropping out.

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In its native state, mottled with lichens and sculpted by wind and water, it does nice things with light.

Erosion also reveals some of the details of the stone. Parts of it are dotted with pebbles, and subtle bedding features cause the rock to flake.

Good building stone had to be selected with care, but in the end there was plenty for the new campus.

This signature stone was also used for some other noteworthy buildings, including the Carson City Mint in Nevada (now the state museum), Lick Observatory, and the Post Office building that now houses the San Jose Museum of Art.

The 1906 earthquake destroyed many of Stanford's original buildings, and the stones were stockpiled and dumped in many places around the campus. The 1989 earthquake added more of the sandstone blocks to the campus boneyard. When artist Andy Goldsworthy was commissioned to create something at Stanford, he was enchanted by this old material. In 2001 he and a crew of traditional English dry-stone wallers used it to construct "Stone River", just east of the Art Museum parking lot a stone's throw from the Oval.

It's a long, sinuous form set in an excavation, like something uncovered by archaeologists. Its shape also hearkens after a streamcourse, like so many Bay Area creeks that have been covered over in our cities. But for me, it works as a seismogram trace. And the builders' tool marks evoke the cycles of human use and reuse that stones have always endured—just another form of erosion in a rock's long journey from sand to sand.

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Stanford's Signature Sandstone