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.

I’ve documented concretions in Oakland before, in rocks of the Great Valley Sequence and in the nameless unit of Eocene mudstone above Shephard Canyon. This concretion is unlike the other two in (I assume) not having a siliceous matrix like the first and not being finely layered like the second. I assume that this is a typical featureless ball of extra-strong mineralization that formed slightly before the rest of the rock lithified. (And on KQED Quest Science Blogs this week, I talk about other concretions in the Bay area and California.)

By the way, I visited the lower end of Joaquin Miller Park the other day, below the Woodminster area where the Miller cottage is, and finally saw my sign about the rocks of the park. I hope that people have gotten some benefit from it.

This walk starts in the bayside flats, crosses two hills and two streams, and returns from the side of a third hill. The first hill is Pill Hill, and the second (Fairmount ridge is my name for it) and third are lobes of the Adams Point upland. These are parts of a larger structure that is central to Oakland’s character, an ancient Pleistocene alluvial fan. Here it is, marked “Qpaf” on the geologic map.

This walk takes in the leftmost edge of the fan, crossing two valleys of the Glen Echo Creek system which dissect the fan. The creek feeds the narrow west arm of Lake Merritt.

All right, here’s the route with the locations of the following photos.

Here’s the view up Hawthorne Avenue to the edge of Pill Hill. The land west of the fan is a modern alluvial flat with almost no topography to it beyond subtle levees along the modern Temescal Creek and the notorious filled-in marsh that once underlay the ill-fated Cypress Structure in West Oakland. The Pleistocene fan has fairly abrupt edges like this all around it.

As you go over Pill Hill and Summit Road on its spine, take a close look at the topography ahead of you. The near ridge is Fairmount ridge, made of Pleistocene alluvium, and the distant hills are Cretaceous and Tertiary sedimentary rocks. The eminence at the foot of the high hills is the older Franciscan block that underlies Piedmont and upper Rockridge.

The walk goes down into the valley of Glen Echo Creek. Brook Street is named for the Broadway branch of the creek, which is culverted under Mosswood Park and runs open to the sky in the backyards here. This shot is at the foot of 30th Street.

If you go upstream a little ways you can spot the culvert where the two branches join.

Next we climb the other side of the valley up a long flight of stairs, then turn right and follow the ridge top, along Fairmount Avenue, for a ways. A detour of stairways leads to Hamilton Place, at the toe of the ridge (the new Whole Foods place cut into that toe; unfortunately I never got a good look at the cut). From here we look across the next valley, which I might as well call Harrison valley.

This valley has a well-developed profile, but apparently it never had a permanent creek. The Oakland watershed map shows only a culvert here. Anyway, we walk up the far side of this valley and return west on classic Perkins Way, where we can look back at the other two ridges.

Back up on Fairmount ridge, we stroll up quiet Kempton Avenue, where this nice driveway wall of California mariposite lives.

Soon enough we find ourselves again at the steep edge of Glen Echo Creek valley. If you limit yourself to walking, Oakland is really quite a rugged place.

At the bottom is a precious remnant of early Oakland’s streambeds, Glen Oak Park. An old concrete bridge crosses the stream, and if you have time to stroll up and downstream there are some fine buildings here too.

I would be remiss not to mention that a little farther, at the foot of Piedmont Avenue, is a good sushi place, Drunken Fish.

Looking at the sculpture toward the hills, you also notice ring-shaped berms invoking the seismic waves that rippled north through the site from the epicenter in the Santa Cruz Mountains.

Here’s a view from the sidewalk looking the other way. The park takes up an L-shaped portion of the block, the rest of which is occupied by a fire station.

The floor of the sculpture pad briefly describes the scene here on 17 October 1989. The edge of the park is a wall with “15 seconds” in big steel letters on it. To the right is an interpretive sign.

This is a remarkable place that I had no inkling was here until I took a walk on Mandela Parkway yesterday. It occurs to me that there must be other memorials to the 1989 quake around the bay.

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.

Today it’s the setting of a toddlers’ playground, without a sign of its former prestige. Nearby is Oakland historical landmark 51, the George McCrea House and Indian Campground. McCrea was the prominent architect who designed the house, and I find nothing online about the Indians. I don’t know if these boulders are part of the historical landmark, but they aren’t being treated like one.

I visited the site a couple weeks ago accompanied by a rockhound and a geologist. The boulders have numerous pits, much like the ubiquitous mortars where the natives once ground acorns.

The material making up the boulders appears to be ancient colluvium cemented by abundant iron oxides. This cementation would not happen at the land surface. They sit on a shoulder of land near a deep ravine of the Lion Creek drainage, evidently exposed by erosion.

The site is not far from the former sulfur mine in the hills above Laundry Canyon, and I was told that other ironstone boulders occur in the neighborhood.

Hematite is an excellent orange-red stain, useful for face paint and similar decoration. There isn’t much around here.

It’s a pit lined with picturesque cobbles and rimmed with gray slate flagstones. A large slate boulder is mounted in the center, and a fountain trickles off a smaller slate stone over the boulder, cascading into the pit with a delightful sound. Thanks for the gift to passers-by.

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.

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.

I was across the bay on October 19, 1991, doing a freelance job at some client whose name I forget. It was a hot day, and I saw a tall plume of smoke in the Oakland hills. The fire people worked on it, and that evening as I headed back across the bay it seemed to be over. But the following day, 20 years ago today, an ember got loose and took out a huge swath of the hills with some three thousand homes on it. It was a terrifying day, like something out of Lord of the Rings. Thick smoke covered the whole sky, and the east wind wouldn’t let up. The city was at nature’s mercy until the winds turned, late in the afternoon. For years afterward we would find pieces of charred wood in our garden that had dropped from the sky that day.

Apparently the same thing had happened in 1970. Historians reminded us that it happened in 1923, too. Before that the native inhabitants made a practice of torching the hills often to keep the land clear. But in the aftermath of 1991 the hills were hastily repopulated and reforested by residents whose driving urge was to make the pain stop. They had the eager help of insurance companies, placing their bets on the enduring value of view lots.

Today these fireprone hills are platted out for houses forever, even the impossible slopes of Charing Cross Road. Now the hills are in an unsustainable cycle of building expensive homes cheek by jowl on inadequate streets, growing inertia as fuel builds up and preparations lapse, one dire day of conflagration, and heedless rebuilding. The earthquake cycle is just a slower version of this fire cycle. If madness is doing the same things in the face of futility, then Oakland has gone mad. It doesn’t have to be this way.