Archive for June, 2008

The fault at Stonewall

19 June 2008

stonewall road

Stonewall Road is a cute little curving street, cozy at the bottom and overbuilt at the top, just across Claremont Boulevard from the Claremont Resort. The street sits at the break in slope where the Hayward fault passes through, its northernmost appearance in Oakland. The nice new red-painted curbs hide the evidence, as so often happens in this town, but I have a photo from 2001 (the second on this page) showing how it used to look. A stairway named Tanglewood Path runs west from the north end of the street, and it’s disrupted by aseismic creep near its top, although tree roots and landslip do their part as well. This view looks southward pretty straight down the fault, which runs along the hillside above the road and to the left of the hotel.

If you come out Stonewall onto Claremont Boulevard and look for fault evidence, you don’t see it amid the cracking and wear-and-tear that normally accompanies a heavily trafficked asphalt road in a stream valley near steep soil-covered slopes. But this wall, on the north side of the road right where the fault should be, makes me think that it must be some sort of homage to the fault. (click it large)

fault wall

There is some more-organized cracking in the pavement behind the hotel. The fault goes onward along Alvarado Road, ducking briefly into a salient of Berkeley then crossing Tunnel Road straight toward Lake Temescal.


Oakland Paving

16 June 2008

oakland paving company

Oakland’s sidewalks are full of old mason’s marks. They’re like fossils in the city’s hardscape. Since I started paying attention to them a few years back, the oldest have reached a century’s age. There’s a mark on 49th Street that dates from 1906, another at John and Gilbert streets from 1907, and several around town from 1908. Some of the makers operated from addresses that don’t exist any more, such as one from a street number that’s now underneath the Kaiser complex, or from streets that have changed their names. If someone has a blog about them (and why not?), let us know.

Just last week I learned that the operator of the Rockridge Shopping Center quarry was called the Oakland Paving Company. The very next day, I spotted this mark on Claremont Boulevard near The Uplands. Presumably, if we broke this pavement open we’d see gravel made of the quarry’s basalt inside. That is, the quarry produced the aggregate, while the cement came from elsewhere, possibly the giant plant in Davenport, which has produced cement since 1903 (and which I’ll be visiting this weekend). My hypothesis is that the Oakland Paving Co didn’t do much of this labor-intensive retail-type work making sidewalks, which is why its maker’s marks are so rare. But they say the best geologist is the one who’s seen the most rocks, and maybe I just need to see more marks.

Fire on the mountain

13 June 2008

hiller highlands fire

Yesterday there was a fairly small fire in a treacherous place, the Hiller Highlands neighborhood. There was confusion in the media accounts I saw, but here is the correct version, as you can see in this view from across the freeway this morning. The streets, from top to bottom, are Charing Cross Road, Tunnel Road, Caldecott Lane and Route 24. (A typo in the Tribune, “Charring Cross Road,” may give you grim amusement.) The blaze began on Tunnel where street work took place a few months ago, and nearly reached Charing Cross. As I shot this photo, fire crews were still combing the burn area in search of embers.

The hills love fire, and the ecosystem is adapted to it, but civilization here is not. Given that we have irreversibly encroached on the hills by permitting residential construction there, we’re stuck with the price in dollars and lives in perpetuity. Not even the next major earthquake on the Hayward fault, less than a kilometer west, will change this even though the whole neighborhood would likely burn down again, just like 1991, if it happened today.

Yesterday not an hour before the fire started, I was standing on Grizzly Peak Boulevard looking down at this part of town and sensing just how dry everything is. Instead of coming down through here, as I have before, I walked down through the Grandview neighborhood to its north. Upper Grandview is an uncanny place, having been wiped out in the 1991 fire and disneyfied since. Today I was going to visit the fire site, but I got this shot because instead I took the opportunity to try the fire road above Broadway that ends overlooking the North Oakland Regional Sports Center. If you visit the park, have a look at the fire-resistant garden there. The rocks are mapped as undifferentiated Great Valley Sequence and are mostly an undistinguished gray sandstone.