Claremont Canyon and Temescal Canyon are large excavations into the rising Oakland Hills, and every is a visitors hall. Between them is a smaller valley — a gulch, actually — that I believe is fairly distinctive, sufficient so to advantage the title of canyon. I identify it Vicente Canyon, after the stream operating down it, Vicente Creek. All three canyons feed their runoff to Temescal Creek, as proven right here within the county’s watershed map.
Take an in depth take a look at it (click on it to see full measurement). The land floor is proven as a digital elevation mannequin, and with out all of the distracting road names and such, some issues are apparent. All three canyons are outlined by the Hayward fault, which runs from high middle to decrease proper. The hills on the east facet are being pushed up, and the ridgetop is round 1300-1400 toes elevation. Vicente Canyon has solely a barely smaller elevation vary, however it’s a lot shorter; that’s, its slope is steeper. The 2 larger canyons are lengthy. Their streams, Claremont Creek and Temescal Creek, have stretches which are virtually stage, however not Vicente Creek. It’s working more durable than its neighbors.
Right here’s a factor individuals might not get about streams: they solely erode and reduce down their very own slim streambeds. Apart from that, all they do is carry away what falls into them. Because the Oakland Hills rise, the streams that drain them are compelled to maintain reducing straight all the way down to the extent of the land on the fault, which is the native base stage. It is a very efficient course of, geologically virtually instantaneous — you’ll discover that wherever tributaries be part of a bigger stream, they at all times meet on the similar stage. The large stream is the bottom stage for the toddler.
Vicente Canyon has extra-steep partitions which are prepared to slip, and as I’ve explored this valley in current weeks I’ve seen numerous landsliding. Right here’s a bit of instance from excessive up within the catchment, on the unbuilt extension of Kenilworth Street.
A scoop of hillside has slumped and rotated on a curving underground floor. The tree died when its roots have been torn off.
Down by the creek itself, the slopes are even steeper. This little bit of Westview Drive suffered a contemporary particles slide (what’s usually referred to as a mudslide) simply final winter, subsequent to an older one.
The state’s official geologic hazard map corroborates me. Right here’s the world that features Vicente Canyon. The blue tint signifies areas at excessive danger of landslides.
The diagonal strip is the official “earthquake fault zone” outlined by the state and the black line inside it’s the hint of the Hayward fault. With that in thoughts, take a look at the digital elevation mannequin of the identical space.
See how the stream bends because it approaches the fault? It’s an important illustration of what the fault does to the panorama. The underside facet is transferring leftward a mean of about 10 millimeters a 12 months. (The uplift half I referred to earlier is extra like 1 mm/yr.) People can’t understand motion that sluggish, however streams really feel it as certainly as we really feel an escalator.
The rocks in Vicente Canyon are virtually completely mudstone of the identical classic because the rocks of Shepherd Canyon.
They’re not often seen, although. They shortly flip again into the clayey sand they began from, as uncovered on this excavation on Westview Place.
As soon as the creek crosses the fault, the whole lot modifications. The rock there may be Franciscan sandstone, considerably more durable. The stream turns into a rocky gorge that winds via wooded yards for just a few hundred meters to its junction with Temescal Creek, which is now culverted. The neighborhood is completely different, however not with out its personal attraction.
All of Oakland’s excessive hill neighborhoods stack elaborate homes alongside slim roads on steep, not-too-stable slopes, however due to its underlying configuration, the Vicente Canyon neighborhood is much more like that. At its greatest it presents an image of architectural and engineering heroics in a stunning woodsy body.
And particularly alongside the canyon’s higher partitions, the views throughout the fault to the San Francisco Bay basin are luxurious.
However the Vicente Canyon Hillside Open Area, a pair acres of oak woods between Vicente Street and Gravatt Drive, is a fantastic place for spry guests. The locals handle a basis that tends the land as a fireplace barrier.
Its benches have million-dollar views and not one of the hassles of residing up there.
