Oakland bricks and clay

17 January 2022

When time began in this part of the East Bay, the people led a lifestyle based on the plants and animals. The Ohlones didn’t build with brick or mud and didn’t rely on pottery, so the soil below was not a concern. Their needs for good clay were modest.

When the Spanish took this land, they found the clay soil excellent for their purposes. “The habitations of these people,” wrote Joseph E. Baker in his 1914 history of Alameda County, “were fashioned of large, sun-dried bricks made of that black loam known to settlers in the golden state as adobe soil, mixed with straw, measuring about eighteen inches square and three in thickness, these being cemented with mud, plastered within with the same substance and whitewashed when finished. . . . When completed these dwellings stood the brunt and wear of many decades of years.”

Some of the adobe bricks from the original Peralta hacienda are preserved in Dimond Park.

Like every frontier settlement, Oakland bootstrapped its way to civilization by using what it had on hand. The very first Gold Rush visitors dug into the ground for resources, looking for what served them in their homelands whether it was good farm soil or something more specialized. In 1850, a French man by the name of Romby located decent clay along the shore of Lake Merritt in Adams Point, and with the help of fellow immigrant George LaFleche started a small brickworks there. The exact location is now lost, but I’ve seen the same promising material in excavations at Lakeside Park. It’s marine clay from the days when the sea level was extra high.

Other brickworks (“Brik Kilns”) sprang up in the early 1850s in the Grand Lake neighborhood, as seen in the Kellersberger map surveyed in 1853. I place this between Cheney and Wickson Avenues, behind the Grand Lake Theater.

There would have been lots of firewood handy for the kilns in Indian Gulch — one reason all of Oakland and Alameda’s oak forests disappeared within a couple of decades.

Romby soon relocated to better raw material on the west side of the lake where the Kaiser Center building sits today, then down to the Melrose area at the foot of High Street, where “Romby’s brickyard” was named as a boundary landmark when the Town of Alameda incorporated in 1854. A court case in 1885 referred to it as “the old brickyard house,” signifying to me that the business had closed shop, but by then it had been memorialized in the name of Brick Yard Slough.

The Remillard brothers (French Canadians) had brick kilns in East Oakland in the 1860s, but as their fortunes rose and the railroads made transport easier, they opened plants near Pleasanton, San Jose and Greenbrae. Oakland was not perfect territory for brickmakers, but it was good enough for small companies making serviceable products.

Premium potteries — making tile products and ornamental objects — found Oakland fertile ground, using coal from Pittsburg and high-grade clay from the Ione area of Amador County, and Oakland became a center of the architectural tile industry.

Pryal’s gold mine

3 January 2022

The Gold Rush was a bust everywhere in the Oakland Hills, with one exception. That was a short-lived mine, started in 1864, on A. D. Pryal’s ranch in the northern Rockridge neighborhood. This seems most unlikely at first blush, but the source is Titus Fay Cronise’s unimpeachable book The Natural Wealth of California (1868):

“In 1864, Mr. A. D. Pryal, owner of a large ranch about four miles east from Oakland, discovered a vein of auriferous quartz in the Contra Costa hills, which cross his lands. Some of the specimens from this vein were rich in free gold, and the mine opened under the name Temescal, paid well for a short time, but the dislocation of the strata, a little below the surface, rendered its further working unprofitable.”

The only remotely likely source for such an ore is a small body of highly altered mantle material, called silica-carbonate rock (also called listwanite or listvenite), that was caught up in the Hayward Fault. Long-time readers may recall a post of mine on the subject that involved this same locality. Here’s what the area looks like on the geologic map.

That’s College Avenue running up the left side and Route 24 in purple running along the bottom, with Chabot Road to its immediate north; Lake Temescal is in the corner and the silica-carbonate is the dark blue wedge just north of it between strands of the Hayward fault. When I explored it nine years ago, I bushwhacked up its western edge and found nothing. This weekend, I bushwhacked up its eastern edge.

This part of town has been heavily built upon since Pryal first dug it up, but old photos from (I think) the 1890s show the possibilities. The first shows the Lake Temescal dam and the creek below the spillway. What would’ve been the continuation of Chabot Road (then known as Pryal Lane) runs in front of the white house at the left. The little bridge at the bottom is where the next photo is.

Notice what a mess the hillside is above the dam. Anthony Chabot apparently sluiced it all into the reservoir when he built the dam in 1868. And notice what an erosional mess the streambed is. Nobody cared back then, or nobody downstream cared enough to sue Chabot.


Photos courtesy Bancroft Library via Online Archive of California

What caught my eye was the boulder at center left. Well, first, the streambank behind it looks like fault gouge, the pale powdery dirt that faults make by grinding rocks (and which I documented down at the London Road landslide). Anyway, the boulder at center left looks just like a big slickenside, the scraped-and-buffed surface that faults make by rubbing rocks.

The gist of all this is that a wide, complex fault zone like the geologic map shows could very easily carry slivers of rock from quite far away. And this is little known today, but in the early days there were curious, isolated reports of stones of gold-bearing quartz in our hills. At least two have popped up in my reading, one from north Berkeley and another from Leona Heights. So my hopes were not high as I set out on this traverse, but they weren’t zero either.

It was a real nice day. The streams had water and the ground was pretty firm and quiet. This is looking down at the head of Chabot Road, which was truncated by the freeway long ago. A strand of the fault is mapped there, but the road shows no sign of it.

I found bedrock this time. One bit was deeply weathered Leona volcanics, the same stuff that crops out uphill to the east (pink on the map).

This outcrop looked more like a strongly sheared and altered basalt, not unexpected in the Leona volcanics.

This outcrop, hard to tell; probably more of the same, brecciated.

None of what I saw appeared to be silica-carbonate rock or even leaning in that direction. But that’s what I would expect 160 years after a minor gold find petered out. I’m still not clear on what evidence led the mappers to think such a thing was here at all.

Besides, I was happy to find real bedrock at all during this visit, and there’s still a bit of the territory I haven’t set foot on yet — something for another day. After a long absence from the field, these rocks all looked beautiful to me anyway.

Lake Merritt’s sister lake

20 December 2021

Fukuoka, Japan is one of Oakland’s sister cities; nothing amazing about that, we have lots of them. But Fukuoka has a special twin it shares with us — a lake converted from an arm of the sea. Fukuoka’s counterpart to our Lake Merritt is Ohori Park.


All photos Wikimedia commons

It’s got boat rentals, a bird island and a Japanese garden, just like we do. It’s in the middle of the old city, just like ours is. But it’s considerably older.

The lake was formerly an inlet at the mouth of the Hii River; then the daimyo Kurodo Nagamasa repurposed it in the early 1600s as part of the moat (ohori) around his brand-new castle, diverting the river and building new land across the inlet’s mouth. To all appearances it’s been a freshwater lake for a long time.

While Lake Merritt has a couple of nice pedestrian bridges in its outlet channel, Ohori Park has four of them crossing the lake from end to end that connect three little islands.

Where we have green, great blue and black-crowned night herons, Ohori Park has the Old World’s gray heron, Nycticorax cinerea.

Ohori Park also has an art museum and a Noh theater. It doesn’t have our free-form public spaces, or our ice-age history and monsters. It’s got a Twitter account, but Lake Merritt doesn’t, far as I can tell. We’re different cities, but our lakes are near-twins.

In Oakland, we’ve been altering our lake for the last 150 years. It started out quite different, as a shallow muddy slough with patches of marsh around it and a muddy shore. It’s been dredged and dammed and armored and built up. Today it’s a highly contrived place, an open-air aquarium.

If we felt like it, we could fill in the channel and make it a one-way floodgate. In not too many years, the lake would turn freshwater, as Dr. Merritt intended when he built his dam back in 1868.

We took this lake into our own hands a long time ago. I like it very much today, but we can change it any time we feel like.

Blair Quarries (not the same as Blair’s Quarry)

6 December 2021

Walter Blair, the first resident of Piedmont, left his name in several places. The quarry he started in the 1850s, now near the foot of Blair Avenue, is now Dracena Park. Everyone called it Blair’s quarry. In the 1880s and 1890s, the amusement park he created in the canyon of upper Glen Echo Creek was a big deal. That was Blair Park.

This post is about the Blair Quarries, and this photo.


From Calif. State Mining Bureau Bull. 38 (1906), slightly massaged

The pit in this photo was the centerpiece of a rock-crushing district on Moraga Road, just above Mountain View Cemetery, that the state mining bureau described in 1906 as “Blair Quarries.” The main quarry was “near the summit of the hill, about 100 yards up the slope north of the road. It was opened in 1901.”

Just ten years before, that same land was part of Blair Park, “the most pleasant outing-place in the bay counties.” By all accounts (and they all seem to be collected at historyofpiedmont.com), the scenic canyon had been turned into a rustic garden fantasyland that included balloon rides, a bandstand, waterfall, garden maze, playgrounds and a “Venetian canal.”

After Blair’s death in 1888, the park eventually fell into the rapacious hands of the Realty Syndicate, which began to devour the valuable chert of the Franciscan melange zone starting in 1901. So Walter Blair had nothing to do with this quarry. At the time this photo was published, the Mining Bureau reported, “The company is opening a ‘blue rock’ quarry, of metamorphosed sandstone, on the south side of the road, and is tunneling in quest of rock for a quarry 50 yards west of and below the larger Blair quarry.” The Blair sandstone quarry, as far as I can tell, was where the Piedmont Reservoir sits today, at Scenic and Blair Avenues. If anyone can confirm that I would be most grateful.

When the city of Piedmont bought the property in 1913, the main quarry was finished. For a time, the Red Rock Quarry worked part of the site. Eventually the pit was filled in, and now the city’s corporation yard sits there. Today, the scene looks like this from the air:

and like this in the digital elevation map.

I think the photo shows the east face of the pit, about 60 feet high, late on a summer afternoon. Twenty men worked there, loading orecarts on at least four tracks. Fortunately, the cemetery hadn’t expanded as far as it has today, so it wasn’t disturbed by dynamite and dust the way St. Mary Cemetery was by the Bilger Quarry.

The odds are that much of the red chert you see in Piedmonters’ yards came from Blair Quarries.