Oakland Geology

I gave up owning a car ten years ago and I’m big on our bus system. The 33 line, as I’ve written, is good for access to the hills of Piedmont and Montclair. The 14 and the 62 will give you a good tour through, not just to, the lower levels of Oakland’s geology.

Both lines run from the West Oakland BART station to the Fruitvale station, but on separate routes that share just one six-block stretch and one intersection. I like them both because they’re residential, not arterial routes; they connect neighborhoods, not endpoints (unless a roundabout ride is just what you want). People get on and off all the way. Here’s the 14, as shown on the street map over at AC Transit.

And here’s the 62.

And here they are superimposed on the geologic map.

Their west ends cross the plain of former ice-age sand dunes that underlies West Oakland and downtown (Qms on the map, for Merritt Sand). It has a very low, almost imperceptible dome shape that you can perceive as you look down side streets. The hills are nice to watch, too.

^{The West Oakland plain from the 14}

^{The downtown platform from the 62}

Both routes dip as they cross the outlet of Lake Merritt, crossing artificial fill (af on the map) laid down on what was once a wide marshy slough.

^{The E.18th Street landing from the 14}

Then they rise onto another very flat plain, just a couple meters lower than downtown. This is the same marine terrace (Qmt on the map) that underlies Lakeside Park, built up when the sea sat extra high for a while in the late Pleistocene.

^{The marine terrace’s east end on E. 14th from the 62}

The two routes cross at 8th Avenue and E. 18th Street, and soon they both leave the terrace and climb into the long set of intricate low hills I call the Fan (Qpaf on the map, for Pleistocene alluvial/fluvial). These are made of million-year-old stream gravel that was uplifted, in my interpretation, along with the bedrock hills of Piedmont by interactions on the Hayward fault.

In the views from the bus, the topography competes with a set of interesting buildings that represent the whole twentieth century, plus glimpses of the hills and the Bay, especially at the higher elevations.

^{Old palm allee of the Smith estate on the 62 route}

^{Topography near San Antonio Park. The 14 runs through this valley.}

They also go up and down some of the stream valleys in the Fan. Both routes touch parts of Brooklyn (14th Avenue) Creek (though the 96 is the best line for that) and they share a stretch of 23rd Avenue Creek. The 14 also follows the valley of Courtland Creek along High Street.

Look for the edge of the Fan’s gravel hills wherever you cross Foothill Boulevard. The 40 line runs along Foothill, following an old Ohlone footpath. I like watching the Fan go by when I ride it.

The east end of both routes, at the Fruitvale station, sits at the northern extreme of an arc of coastal plain that extends unbroken around the Bay to South San Francisco (Qhaf on the map, for Holocene alluvial/fluvial).

^{At High Street, E.14th heads across the flats as seen from the 14}

Once these flats were all orchards and farmland that made the Bay area (and Oakland) an agricultural powerhouse, and Fruit Vale, the floodplain of Sausal Creek, was one of the earliest nuclei of that industry.

Other bus routes go through the Fan and offer similar rides, but the 14 and 62 really focus on it. The 57 and NL are classic arterial routes that cross the Fan on its high inner side. If you happen to catch one of the plush transbay commuter buses, the NL can’t be beat but the 57 will give you Oakland color from end to end. The Fan ends just before the Eastmont Center at 73rd Avenue; Evergreen Cemetery sits on its tip.

The last thing I want to say is that AC Transit is going to be taking a hard look at its routes soon. I intend to enjoy the 14 and 62 when I can and speak up to preserve them.

I’ll get around to geology in this post, but there are a few things to say first.

We’re in a new period of time when the unknown looms larger than usual and all seems pervaded with uncertainty. No one knows much, even the experts whose job it is to know. The foundations of daily life are on hold for most of us, and for some of us the foundations are gone. Few of us have been tested for the Covid virus, and a negative result only means we’ve escaped for the moment. We’re told to adopt new habits, drastic ones. They’re hard to learn and may be hard to sustain. The best way I can think of them is, every thing and every person out there is molten lava. The soundtrack is “U Can’t Touch This.”

Most of us will survive this plague, but none of us will be the same. Oakland old-timers like me have seen this sort of crisis before: in 1989, when the earthquake struck. But to most of us it’s new, still sinking in.

I’m trained in science and saturated in science, and I’m friends with uncertainty and the unknown — at least, with the ideas. The reality of this much uncertainty and unknown is daunting.

The empty streets and shuttered shops are like something from a disaster movie. Some of us seem to be living in one, others living in their own worlds. The communal stroll around Lake Merritt has become fraught as runners bull their way past, panting and sweating like zombies, as if they could outrun the six-foot rule. (We’ve got to start moving in the same direction to limit our exposure to each other.) Drivers are so thrilled by the newly open roads that they rush about in their deadly machines as if they were creatures of steel themselves, reenacting the advertisements that drew them to the car dealer. (We’ve got to phase out these noisy, noxious internal-combustion vehicles.) The disaster movie is where the beggars and homeless and impoverished have been living all along.

All right; enough of that. I’m trying to write about some ways to behave I can recommend. We were told we can still go out to exercise, and the first weekend after that directive was a disaster. For some reason, people rode their deadly machines in droves to mob the hills and beaches, cheek by jowl and swapping germs, as if they thought no one else would show up. Such people have the mistaken idea that remote preserves of selected scenery are the only things that qualify as nature. It must be those fucking car ads.

I said, enough of that: the spasms of consternation and dismay, the clamor of alarm and blame. You can get that anywhere. It even infects a contemplative introvert like me.

I recommend slowing down in every respect. When the hospitals are slammed, none of us can afford an injury. When circumstances push us out of sorts, none of us can afford to freak each other out or play games. Ease up; grant slack. Repeat as needed.

I recommend staying out of the parks and straying into the neighborhoods. People who walk their own dogs are already hip to this, right? So consider taking yourselves for a daily walk, gently leashed.

Walk, don’t run. If you sprain an ankle or blow out your knee, the doctors are too busy to help. When they say we can still go out for exercise, they don’t mean stay in personal-best shape with our accustomed Fitbit workouts. Please give that up for something more physically moderate with more room for the brain: attentive motion. Stirring your limbs and looking around, not more reps and more miles, is the basis of good health.

You don’t need a state park or a wide beach, just a spot to see the spring arrive. It always does.

And we live in an exceptionally scenic place on all scales. I’ve walked every bit of Oakland, looking intently, and each block has beguiled me with some treasure: an interesting yard, an unexpected view, a genial neighbor. There are treasures in deepest Deep East.

Treasures in Maxwell Park.

Treasures as close as your nearest parking structure (with stair-climbing as a free bonus).

If you’re still drawn to feats of strength, I have a bunch of Oakland geology walks for you to contemplate, with elevation gains, no crowds and views to fill the hungriest eye. (Just go to the home page and click the Oakland geology walks category.) These shots are from a leg of the Lake Merritt in 2100 walk that I took yesterday.

And while you’re out, meet people’s eyes, put the phone away and do the six-feet thing. That is my recommendation. Oh, and take note of the rocks and the landforms; that’s where geology begins.

This pandemic is a disaster unlike the earthquake, which was instantaneous with a long aftermath, or the drought, which was agonizingly slow and over after a rainy winter. But when it comes to our fabric of mutual well-being, disasters have a lot in common. Dr. Lucy Jones is California’s go-to public authority on earthquakes. Her book on natural disasters, The Big Ones, is a string of insightful pearls with this one at the center: “We must remember that the most dangerous threat in a disaster is a threat to our humanity.”

Temescal Canyon isn’t a name anyone uses. It’s kind of a ghost canyon, even though you’ve all driven through it many times — on Route 24 going to and coming out of the Caldecott Tunnel.

Underneath all the spaghetti and labels on that Google map is what remains of a fine little valley with steep sides and permanent streams that was once the principal water source of Lake Temescal, Oakland’s first surface reservoir. Here’s how the 1897 USGS topo map showed it.

Notice the stream northeast of the lake. The solid blue line signifies a perennial, year-round stream, and by the rules of hydrography it claims the name Temescal Creek given to its lower reaches, and hence comes the name Temescal Canyon. The other stream feeding the lake from the southeast is marked with a dot-dash line, indicating an intermittent stream; the map labels it Kohler Creek after the name of a landowner in Thornhill Canyon, but today that’s the creek called Temescal.

This annotated version shows two things: the arrows mark the Hayward fault and the dots outline the rim of the canyon.

Because the east side of the fault is rising, thanks to a bit of compression across the fault, the stream is forced to dig down harder than your average creek as the hills around it rise, and the long-term result is a watershed that’s wide at the top and narrow at the base — a wineglass canyon. As you know from my previous posts about Claremont Canyon and Shepherd Canyon, I have a thing about hiking around the rims of our wineglass canyons. This post is about that.

I call this a ghost canyon because waves of human intervention have modified it pretty seriously since that 1897 map. The original Kennedy Tunnel was punched through the hill in 1903, with the original Tunnel Road leading up to it. The 1915 topo map shows that when they built the road, the mapmakers added new detail to the contour lines on that side of the canyon. (Also, Oakland annexed all the land uphill from Berkeley.)

In addition to Tunnel Road, the Oakland Antioch & Eastern Railway was pushed through, skirting the lake on its way to the Shepherd Canyon tunnel. It ran over the Temescal Creek arm of the lake on a trestle.

Next came more infrastructure: PG&E constructed a big power line along with the Claremont “K” substation on Landvale Road in 1922, a classic industrial Deco structure. And then the Broadway Extension leading to the first Caldecott Tunnel bores carved up the sides of the canyon mouth even more in the 1930s. By this time, the Temescal Creek arm of the lake had been filled in. The work consumed huge quantities of rock, which was quarried from the north side of the canyon ( a few details here). Meanwhile residential development began on the north canyon wall. All of this is visible in the 1947 topo map.

Between then and now there was more residential development in Hiller Highlands, the big Parkwoods apartment complex in the canyon, a major expansion of Route 24 (with more quarrying to support the work), and finally the other little valley in the canyon was filled in to make the North Oakland Regional Sports Center. All of that was before the third and fourth Caldecott bores were added in this century. All that mayhem and erasure is what makes me think of it as a ghost canyon.

This patchwork of development has not created a ready set of roads to follow for a circumambulation, but I think I’ve cobbled together a trek route. And while I’ve walked all of it at one time or another over the years, I haven’t done it in one go. In fact I’m not eager to do so because it’s strenuous and a bit fraught and I need to build up strength first.

You can zoom in and explore this route at gmap-pedometer.com; this image (click to see it big) uses the OpenCycle viewing option. It starts at the Firestorm Memorial Garden at the foot of Hiller Drive, and right away goes seriously off-piste with a steep climb up the far side of the great Tunnel Road cut.

There are three fairly level stairsteps in the cut to choose from; this is the view back from the second. All three have cool views, and you avoid the heavy traffic on Tunnel Road.

The route veers off Hiller Road into a seekrit pathway that overlooks major features of the lower canyon. The power station and freeway lanes squat on the grave of the creek, with the Hayward fault slashing through the lake toward the notch in the horizon.

The spur across the narrow mouth of the canyon, carved flat for the powerline poles, is the endpoint of this trek.

And the ballfields of the sports complex smother this former stream valley. The woods to the left are an impenetrable eucalyptus thicket.

The next three miles-plus call for cautious walking: cars don’t expect hikers and the roads are narrow. But you’re high in the clean air well above the worst of the road roar. A little past the 3-mile mark, where the power line crosses the road, is an excellent place to stop discreetly and look down the ridge that forms the south wall of the canyon. That road in front of the ridge is Broadway Terrace, perhaps Oakland’s most dangerous road for pedestrians.

The long detour between miles 3 and 4-1/2 is unavoidable (trust me on this), but you can skip the last bit of Grizzly Peak Boulevard by turning right onto a footpath that’s part of the Sibley Preserve.

A little ways down Broadway Terrace is where it might feel a bit hinky. At Pine Needle Drive, you climb over the fence and locate a teeny footpath, almost a deer trail, along the power line that plunges about 200 feet to a fire road, which then climbs all the way back up to the ridgeline past a big landslide. Believe me, that is less fearsome than walking on upper Broadway Terrace.

The last leg, from the ridge down to the powerline tower pad, I can’t really vouch for as I last walked it 11 years ago. Assuming it’s not too overgrown, you should be good, and if not, then go back on the fire road down to the sports center. The pad is at the end of Pali Court, and the view back to the starting point looks like this.

Getting to and from these two endpoints is an exercise left for the reader, and I do mean exercise.