Introducing Deep Oakland 5: The Piedmont Block

Oakland is unusual in having Piedmont, an independent city, entirely inside its boundaries. Geology accounts for that. Little Piedmont got its start with resources from the little range of hills it sits on: water, soil, stone and prime residential land. Chapter 5 of Deep Oakland is about that set of rocky hills, the same hills that Mountain View Cemetery sits on. It’s the forested ridge in this view from the north side of Claremont Canyon.

The hills are the top of an uplifted block of the Earth’s crust in an unusual place: the west side of the Hayward fault, where almost everywhere else the west side is being gradually pushed down and buried. The rocks in it belong to the Franciscan Complex, which I introduced in chapter 4. The upper part of it is melange, which is apparent as one crosses the fault from Montclair to enter the block:

The landscape in the Piedmont block feels different from the high hills east of the fault with their roller-coaster roads and steep, straight flanks; the slopes here are gentler and more rounded. What’s different is the Franciscan bedrock underfoot.

This chapter, like some of the others, traces a route and has a direction. It leads from the pass at the top of La Salle Avenue down the full length of Blair Avenue and ends at the lower edge of the Piedmont block at Broadway and Pleasant Valley Boulevard, former site of a rock quarry. Along the way the melange gives way to hard sandstone, “rock that was once worth money.”

Blair Avenue is named for Piedmont’s first American landowner, Walter Blair, a farmer from Vermont who bought property in these hills and started a dairy farm and a rock quarry to serve the young town of Oakland below. The profits helped launch Blair’s other projects: a resort centered on the mineral springs of Bushy Dell Creek, a family-oriented nature fantasy park, selling residential lots to wealthy white people and operating a streetcar line to and from Oakland to serve Blair’s realm.

The mineral springs are now remembered in old photos and in reconstructions with interpretive signage.

The bedrock on Blair’s land was the nearest source of stone for Oakland builders, thanks to its odd position west of the Hayward fault. And Blair cashed in when the city began a major infrastructure project: paving the sandy streets of downtown Oakland with crushed stone by the macadam method. Other quarries soon started up, and after a few years two of them, the Oakland Paving Company and the Alameda Macadamizing Company, teamed up in a competition-quashing duopoly that lasted until asphalt and concrete paving succeeded macadam, around 1900.

By then the pattern that Blair began was set: wealthy residences covered the desirable hills as the quarries began to fade. The residents of Piedmont voted to incorporate in 1907, two years before Oakland annexed everything around the new city and made it an enclave. Just as Oakland had begun as a genteel refuge from raucous San Francisco, so Piedmont became a place apart from the booming city around it, as did the ring of Oakland land that adjoins it.

The quarries closed, but the old pits couldn’t hide. Today they offer access to the same rocks that compose Mountain View Cemetery’s hallowed ground.

I love quarries, the way geologists do, as scalpel incisions that expose the underworld in detail. I’m grateful for their old, slowly healing scars. The quarry stone from the Piedmont block was well suited for building roads and foundations: hard, durable and consistent. It could be predictably crushed into clean stock and sorted easily into different size grades. One could make steady money with it by keeping costs low.

There have been at least six rock quarries in the Piedmont block. The two that most people see are the one holding Zion Lutheran Church on Park Boulevard . . .

and the one holding the Rockridge Shopping Center, which for much of its eighty-odd years was the largest quarry in Alameda County.

What does the Piedmont block mean to the larger landscape around it? Its location near the Bay, on the west side of the Hayward fault, means that it collects rainfall in a broad, unified catchment. For the last million years or so, every time there’s a great rainstorm the five permanent streams on the block feed that water toward the Bay in a strong, coordinated flush. If you recall from chapter 2 that most of the time, geologically speaking, the Bay is a dry plain, you’ll see why those streams keep digging a deep ravine where Lake Merritt sits.

The two odd landforms, Lake Merritt and the hills of Piedmont, are related. Okay, thinks the geologist, now what accounts for the Piedmont block? I present more clues and a hypothesis in the next chapter.

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