Oakland Geology

For years I’ve been working on a book manuscript about Oakland’s geology. (The first draft of the second version is nearly finished.) It’s an intense mental project in which I must strip back, like layers of wallpaper, the human overlay upon our soil, rocks and landforms to contemplate the natural setting beneath it all. The whole time, I’ve also been walking around all parts of this city snapping photos of things that strike me. Many of them have been in the flats.

Sometimes geology matters where it seems to be absent. The dazzling variety found in any walk in Oakland’s flats rests on a geological foundation that is nearly ideal for human activities. It’s a canvas ready for painting with wave after wave of civic expression.

The Oakland flats — pretty much everything between the Bay shore and Broadway and Foothill Boulevard — served the Ohlone tribes as a bountiful meadow. The flats served the Spanish and the Mexican Californios as a fertile unfenced cattle range. None of that land exists any more. We have to envision it beneath a century and a half of development, then recognize it as the product of truly geologic time.

The flats are a wide, gently sloping apron of sediment washed out from the hills by around a dozen different little streams.

In East Oakland the apron rises to about 100 feet elevation; about twice that in North Oakland. The streams aren’t strongly committed to any particular course. Over thousands of years, they strew their mud and gravel all over, like firehoses dropped loose on the ground, or groundskeepers carefully watering down a ballfield. The result is an even plain, intricate underneath but level on top, with subtle undulations made visible only by looking down our longest streets.

The streams were easy to cover and trap in tunnels. Temescal Creek in North Oakland was an early victim. Despite efforts to “daylight” it here on Telegraph Avenue, apartments now cover it with the same finality as any other spot in the flats.

But across the street the creek is commemorated, as it is in a few other spots. Awareness is dawning that our landscape was once very different and can change again.

And if the abundance of the Ohlone’s meadow in the flats is lost to living memory, here and there it is recalled in art.

To the earliest American settlers, the flats were famously productive farmland. The virgin soil could grow carrots the size of your leg. The last remnant of that farmland, off 105th Avenue at Oakland’s farthest verge, is being revived next to this lot by Planting Justice in collaboration with a land trust that will give the Ohlone people ownership of a new foothold in their native ground.

The peach groves of Fruit Vale helped make Alameda County the richest county in the state. They supported canneries that old-timers still remember as bustling enterprises. Livermore Valley wheat was milled and turned to food in Oakland, where industries of all kinds set up shop near to rail transport and the plentiful groundwater of the flats.

To the founders of early Oakland the flats were ideal for laying out the roads and rail lines and heavy industry needed to support a great city. It was good ground as well as excellent soil. When waves of residential developers filled the flats with subdivisions, they praised the locale’s sun and soil. Odd imperfections show that not every scheme worked out as Oakland grew, but still it became a great city.

The enormous freeway system of the twentieth century relies on the same firm ground, and it hasn’t suppressed the flats’ inherent fertility.

Can you see this part of our geology? Maybe now you can. Unsung and invisible, the flats are fundamental to Oakland’s character. With apologies to Walt Whitman, you will hardly know what they are or what they mean, but the flats are good health to us nevertheless, and filter and fiber our blood. The flats are full of charm and support our spirit. That is what delights me as I walk this part of town.

^{Chris Granillo Art}

Without the flats, Oakland would not have its soul.

This entry was posted on 7 December 2020 at 8:01 am and is filed under Oakland sediment and soil. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.