Oakland Geology

This post takes a look at lobe 3 of the Fan. To orient you as we start, here’s where lobe 3 fits in the bigger picture on the geologic map.

This is the best time of year to walk around the Fan, in the Oakland midlands. When the trees are bare you can see farther and better — the landscape’s bones stand out, and the homes do too. So get yourself on out!

This lobe is more difficult to explore than the others. One problem is that the trees are larger and the landscaping thicker, which makes it hard to get a good view around you. Another is that the streets are laid out in a distributary fashion — that is, you aren’t expected to drive through it except in a couple of places. You’re supposed to drive into it, to your single-family home or small apartment building, and out of it, to work or shop. So getting around in any other direction is not straightforward.

Maybe this will be clearer on the geologic map. For convenience, I’ve divided the lobe into four sublobes.

I tend to analyze landforms from their ridgetops and divides and saddles, features on top of the land. But lobe 3 may be easier to comprehend as a set of stream valleys dissecting a highland, as shown in this watershed map from the county flood control district.

As with the other parts of the Fan, the edges of lobe 3 are pretty clear-cut. This is typical of eroded landscapes in arid country, which is interesting because Oakland isn’t especially arid these days. It was during glacial times, though. Here’s the north edge at the south end of Ramona Avenue, just west of Mountain View Cemetery in the valley of Glen Echo Creek.

This view across the Glen Echo Creek valley up Monte Vista Avenue gives a better idea of the height of this lobe — about 80 feet here, but it seems like much more.

At its westernmost edge, the lobe starts right where the Whole Foods store stands. Everything in front of the far hills is part of the Fan.

This shot from the toe of the Calmar sublobe shows why the Fan has always been land to make homebuilders salivate: fantastic views of the city, the Bay and the Golden Gate. Adams Point fills the middle ground.

And here’s a final view across the edge of the lobe, this time as seen from the freeway overpass over the homes in Trestle Glen. Longridge Road along the top gives its name to this sublobe.

The Adams Point sublobe is larger, but a little lower than the others, reaching about 160 feet elevation. Its highest ridge, along Fairmount, Kingston and Rose Streets, offers good views north toward lobe 2.

Points on the other side, like Jean Street and the knob of Nace Avenue, overlook nice vistas south and east. Or Cambridge Avenue.

The Warfield sublobe is a highlight of geology ramble 4. Whereas the Adams Point sublobe has saddles where three roads cross it (Santa Clara, Linda and Grand Avenues), you have to hump Warfield Ridge over Mandana Boulevard, as here:

or go up the Bushy Dell Creek valley on Wildwood Avenue and over to Winsor Avenue. In between it’s a bit intimidating, as seen from the foot of Jean Street.

The Calmar and Longridge sublobes are the highest, reaching well over 200 feet elevation at their upper ends. Longridge is particularly hard on landscape photographers because there are so many mature trees and big homes. (If only it were 100 years ago, when this whole tract was bare hills.) But I like this shot from Long Ridge. On the right edge it shows the red-brick Grandview Apartments building (Warfield sublobe), the Spanish Revival apartment complex on Crescent Street (Adams Point sublobe), and behind them the big palm tree at the top of MacArthur by the Chetwood overcrossing. A little bit of Elwood Street is visible to their left.

But if finding big views is frustrating, it’s easy to find cute little pocket valleys all over lobe 3. The only one I’ll point to here is the one with the Morcom Rose Garden in it.

Here’s where all twelve photos were taken.

This entry was posted on 22 January 2018 at 8:02 am and is filed under the Fan. 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.