The Oakmore block

The Oakmore district is quite a distinct part of town. Here’s how its geology makes it so. I’ll call it the Oakmore block, although that’s a bit of a misnomer—it’s the eastern end of the Piedmont block.

oakmore-geomap

The neighborhood is defined by the light blue of Franciscan sandstone of the Novato Quarry terrane, bounded by three canyons. The canyon on the northeast side is occupied by Route 13, of course, which corresponds to the Hayward fault. Here’s the view across it, looking east from the easternmost corner of the Oakmore block (the end of Braemar Road) to Joaquin Miller Park. The top of the grassy slope is the overlook at Lookout Point.

joaquinview

Dimond Canyon on the west is the most dramatic boundary, but the bedrock is the same on both sides; there is some accident of geologic history that has maintained this deep streamcut. Leimert Boulevard defines that side of the neighborhood. Roadcuts about midway up Leimert expose a lot of strong sandstone like this.

leimertcrop

And on the southeast is an unsung stream valley cut along the edge of the Piedmont block. Whittle creek, I guess I’d call it, because Whittle Avenue runs up it, and the Head-Royce School is nestled in it. The valley grows into a nice amphitheater at its head. This is the view from there—the end of Melvin Road—across to the Greek cathedral and Mormon temple. Lincoln Avenue is the ridge road on the other side of this valley.

oakmore-temples

Over here I see more shaly bedrock, like this stuff exposed on uppermost Fruitvale Avenue . . .

oakmore-shale

. . . and bit more structure here where Wrenn Street meets Hoover Avenue.

oakmore-wrenn-hoover

All of this is expected in the Franciscan. The odd bit I haven’t figured out is near the end of Melvin, which looks to the naked eye like a volcaniclastic rock. Perhaps the boundary on the geologic map is a little off.

oakmore-volc

All I know is that when you take your eyes off the ground and look off toward the Bay, Oakmore is a mighty fine place.

oakmore-view

I don’t know exactly where the realtors put the southern line, but the dotted-line contact running from Sausal Creek along Whittle, marking the hidden thrust fault at the edge of the hills and the bedrock alike, works for me.

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