Radio Tower Hill

On Tuesday the skies were so clear I made a point of visiting the hills. Not as clear as Monday, but from the top of Radio Tower Hill this is how the Golden Gate looked. Remember this when the weather is dismal.

Click the photo for a 1000-pixel version. That’s the Farallon Islands on the horizon, perched at the edge of the continental shelf on the Pacific plate. They consist of the same granite found on Point Reyes, Bodega Head, Montara Mountain and points south in the Salinian terrane. The blob just below them is a freighter bound for the Port of Oakland, or perhaps a tanker bound for Point Richmond. Downward in the image is the bridge, Alcatraz Island, Treasure Island and the foot of Ashby Avenue in Berkeley.

Radio Tower Hill doesn’t really have a name. It’s the hill at the intersection of Grizzly Peak Boulevard and Marlborough Terrace. It’s made of Claremont chert.

The view from Panoramic ridge

I’ve posted three other shots from the walk I took in late May to the ridge at the top of Oakland’s own Panoramic Way, overlooking Claremont Canyon. This is the view south over the rest of Oakland; click it for the 1000-pixel version.

The homes in front are in the Grandview neighborhood, and behind them are the tight ranks of Hiller Highlands. The dark notch beyond is where the Hayward fault runs. On the right side we have Broadway Terrace, the blond summer sward above the top of Mountain View Cemetery, and beyond them San Leandro Bay and the airport on the peninsula known as Bay Farm Island.

Every year this hill repeats this season. I must return here, too.

The Albany Hill walk (#35)

Here’s another stairs-and-paths walk from Charles Fleming’s Secret Stairs East Bay covering Albany Hill, the “little hill” for which the city of El Cerrito is named. I covered its geology last month for KQED Quest Science Blogs, so this post is more about the details of what you’ll see as you take walk 35. Here’s the route map starting from the El Cerrito Plaza BART station. In the book, the route starts at San Pablo and Washington, but I have an extra path that’s not in the book. The numbers represent the photos in this post.

Next is the topography . . .

. . . and here’s the geology.

The geology’s pretty simple: the hill itself is typical Franciscan sandstone of the Novato Quarry terrane, surrounded by Quaternary sediment shed from the Berkeley Hills. Cerrito Creek runs past its north end, and Marin Creek’s drainage lies to its south. The divide between them is a low ridge of older alluvium where Solano Avenue runs. This accident of topography, making Solano a ridge route, is a subtle but important part of that street’s charm (like Park Boulevard in Oakland).

We start to hit bedrock around the first set of steps—duh! That’s what makes the hill so steep. This set of steps, Catherine’s Walk, is the worst.

Now it’s worth looking around as you proceed. First come views west over the Bay. Click this one for a 1000-pixel version: in the Bay, left to right, are the Albany Bulb, Brooks Island, Point Isabel and Point Richmond; across the Bay are the Golden Gate, Marin Headlands, Angel Island, Tiburon Peninsula and Mount Tam, each and all worthy geological outings.

Once you enter Albany Hill Park the bedrock starts to emerge more. The real opportunity to inspect and sample it comes later, though.

The trail winds up the crest of the hill through eucalyptus woods, for a special experience. The people who planted these didn’t have anyone’s pleasure in mind: they were dynamite-makers who needed a fast-growing screen to help muffle explosions. (The same thing happened up at Point Pinole.)

Up here you start getting views to the east. The rocks in the Berkeley/Oakland Hills are much younger than where we stand: about 10 million years old as compared to the 80-ish million years of the Franciscan here.

At the park’s north end we hit the top of Taft Avenue and take it down the east side of the hill. Don’t miss the view south. Behind the downtown Oakland skyline is Black Mountain, south of Palo Alto.

Along Taft is a long roadcut where you can poke and bang the bedrock to your heart’s content. Unfortunately it’s pretty featureless sandstone. It points to a geographic setting, long ago, when huge quantities of fresh sand were being generated and carried offshore to waiting basins, perhaps at the bottom of submarine canyons like today’s Monterey Canyon.

Now if you scrap the last part of the route given in the book, and instead stroll north on Adams Street to its end, you’ll find a cute little path running along Cerrito Creek back to San Pablo.

Albany Hill and Cerrito Creek have a history of neglectful exploitation, but they have allies today in the Friends of Five Creeks.

Radio Beach

Radio Beach is Oakland’s nearest thing to a natural beach. It’s city land, on the north side of the Bay Bridge approach past the toll plaza. There is no lonelier or prettier spot on Oakland’s waterfront. This is the view toward the bridge as you enter the beach.

This was near low tide yesterday, and the mudflats stretching all the way to Emeryville were tempting. Here’s the view back from the other end, with some of the radio towers.

And here’s the view out, with Mount Tamalpais, Angel Island and the Tiburon Peninsula on the skyline. Click the image for a 1000 pixel version.

The sand is very fine grained, given the energy of the waves and the available sediment in the Bay. It collects here where a little extra wave energy gets focused, against the buttress of the bridge approach. Not a super beach, but a real one.

Upper Claremont Canyon

I’ve been busy, and October is the climax of the business. But I have a fond memory of May 26, when I hiked up to and past the end of Panoramic Way into the open lands of the Claremont Canyon Regional Preserve. The ground here is mapped as undifferentiated sedimentary rocks of the Great Valley Complex. Because the map doesn’t give it a name, I name it Panoramic ridge. This is the view east. Click the photo for a 1000-pixel version.

I wonder about the pattern of the ridges that jut west from the ridgeline, but that’s an intellectual task for another time. For now my main thought is, We live in such a beautiful area.

I’ll be out of town for much of the month, so don’t expect a lot of new posts for a while.

Panoramic panorama

Panoramic Way, the northernmost street in Oakland, is well named. Here’s the view west from there, across the Cal campus, Albany Hill (El Cerrito), Point Richmond and eastern Marin County in late May. This was a beautiful summer, once it got started.

Click the photo for the 1200 x 900 version.

Glenview walk (#23)

This is another path-and-stairways walk from Charles Fleming’s book Secret Stairs East Bay; his description of the homes and streets is good, but I’m here to talk about the geology you’ll see en route.

The walk starts on Park Boulevard, which is one of Oakland’s premier ridge routes, maybe its best. On its north is Indian Gulch, later known as Trestle Glen, and on its south is Dimond Canyon. Trestle Glen Creek is now culverted, although its waters still run free upstream in Piedmont. Dimond Canyon and points downstream, of course, feature Sausal Creek. The whole idea of Glenview the neighborhood is that from Park Boulevard you could overlook glens—secluded wooded stream valleys—on either side. (Such honesty in marketing may seem quaint today.) The walk route (created using gmap-pedometer) traverses stairs and pathways on the Trestle Glen side:

Here’s the topography, courtesy Google Maps, with the photo stops marked as well as the bedrock line between the Piedmont block and the Pleistocene alluvial fan at Oakland’s heart. See the Oakland geologic map for context.

The walk begins on Park Boulevard, going up the gentle slope of the remnant fan. I would love to see what’s beneath these homes, but how likely is that?

As you rise, the hills emerge as does the occasional vista. The Glenview really is the everything-view.

At this point the walk leaves the spine of the fan and wanders the slopes and floor of Indian Gulch. The mature palms and lush vegetation combine with steep slopes (though not the insane slopes of the high hills) for a distinctive charm.

Again, watch where the trees allow a peep through. Homeowners with their upper stories are privileged over streetwalkers in this respect.

On Elbert Street, a patch of rustic funk, emerges bedrock—just a prosaic Franciscan sandstone here. Perhaps more crops out along the power line through this neighborhood, but I was here to follow instructions and did not check.

The walk delivers us to the floor of Indian Gulch, long since vacated by its namesake indigenes, converted from a park (with trestle) and turned into a classic upper-middle-class residential district. The narrow road and steep-walled valley give it a uniquely intimate feel. Farther up the valley, what looks like real woods is just the hinterland of what appears to be Piedmont’s largest private lot.

The walk leaves the valley floor at the foot of Barrows Road. Higher up you begin to glimpse the high hills again above the densely settled slopes.

It appears to me that the bedrock portion of the stream valley is a bit steeper than the alluvial-fan part, but not by much. The transition between them is quite subtle. The fan sediments are well compacted and bound with firm clay.