Survivor trees

10 August 2015

I’ve been poking around Oakland’s edges lately. In southernmost East Oakland there’s not a lot of geologic history, but there are some big old trees, survivors of optimistic times, plus nice views of the hills and sky.

This is one of our largest and oldest jacarandas, on 92nd Avenue. (There’s a comparable one on Pippin Street.)


And here’s an even more exotic visitor, an Araucaria from the southern hemisphere (a monkey-puzzle tree, I think) in Sobrante Park.


On 105th Avenue, next to what appear to have been Oakland’s last commercial greenhouses, we have a big old lot where there used to be something but now there’s just a large generic tree. What has it survived?


The ground here is mapped as Bay mud, just past the seaward edge of the alluvial fan of San Leandro Creek. If the soil is still clean, it should be rich stuff.

Down at the end of 105th Avenue, hard by San Leandro Creek, is a cluster of venerable black walnuts.


Unlike the previous trees, these may well be natives. At least the species is right and the riparian (streamside) habitat is correct.

There are surely people in Oakland who remember the stories of these trees.

But I really wanted to talk about another old survivor tree, up in the hills on the south side of Horseshoe Canyon. In fact “Old Survivor” is its name. This last week I had the opportunity to visit it with a small group of people. It’s older than any human memory in these parts.


The group tended to refer to the tree as “the Grandfather Tree.” I thought “Grandmother” was a name just as good. But the DAR, in chiseling “Old Survivor” on this monument by Campus Drive at Carl Munck Elementary School, established priority. The age is subject to revision, though. The 1981 monument put the tree’s age at 425 years, but there’s no birth certificate for this baby. The tree was cored in the late 1960s, and its age at that time was estimated as 415–420 years. Let’s make 1550 its germinal year. So today it would be 465 years old. Here it is.


The Old Survivor is about 100 feet tall and has presence, especially when you think of it as the last old-growth redwood left in its East Bay stronghold. However, the loggers let it be because it was, and is, a scraggly, marginal specimen. Part of its uphill side is bare, fire-scarred wood. It’s flanked by two nuisance trunks that were less than marketable size in the 1850s redwood rush. The slope it sits on is more of a cliff, and had it been toppled it would have shattered.

The Old Survivor is rooted on Leona “rhyolite” rather than the moist mudstone of the Redwood Formation or Oakland Conglomerate that redwood prefers. But it’s fitting that Oakland’s oldest tree grows from Oakland’s oldest rock.


While the tree consists of a triple trunk, the central trunk stands above its siblings pretty well, if I can judge from the photos on oaklandwiki. I took a photo of its crown from the west side.


Old Survivor isn’t pretty, and it’s very hard to visit, but it’s still precious: the last bit of our forest primeval.

The Skyline median trail

3 August 2015

My latest outing took me to what I’ll call the middle part of Skyline Boulevard, the part where the road is divided. Starting at Skyline High School and going south for about 2 miles, a footpath runs in the median. It’s a hidden gem. This is the nearest thing Oakland has to a long walk on a country lane.


Nobody online talks about this trail. I don’t know who made it or who maintains it. Cyclists laud the paved road, of course, which deserves the praise. The MBTR mountain bikers site reviews it under the name Skyline Boulevard Singletrack and gives it high marks, but you’d have to be as singleminded as me AND a mountain biker to seek it out. But the path is a nice way to enjoy this part of the hills.

This end of Skyline is exclusively on the Oakland Conglomerate, which holds up the spine of the ridge. Here’s the terrain:


And here’s the geology, with “Ko” representing the Oakland Conglomerate (this is the same sequence seen in Shepherd Canyon):


Some parts of the bedrock are straight sandstone.


But almost everywhere along the trail you’ll see the rounded cobbles that are this rock unit’s most distinctive feature, either embedded in stone or weathered out like this.


A slight detour up Brandy Rock Way will bring you to this fine exposure of the vertically tilted bedding, with a thick sandstone bed and conglomerate on either side (1000 pixels).


The road is slightly off the actual crest of the ridge, so the views it offers are mainly over the Bay. Here’s a spot near Cathy Lane overlooking a vineyard, the row homes across Leona Canyon on Campus Drive, the airport tower, the Bay and the San Mateo Peninsula.


I’m thinking that this would make part of a nice ramble. Farther south, Skyline merges into a two-way road and the path continues alongside it. Later this summer I’ll get to that part.

Meet Knowland Park and its rocks

27 July 2015

The neighbors of Knowland Park have something special in their midst: a large stretch of relatively untouched land of the Oakland Hills. If you’ve never been up there, it’s easy to dismiss it. It’s exclusive. You need a car, and there aren’t amy big entrances and signage. Only one bus line (the 46L) goes through it at all, and that’s only once an hour. But I urge you to make the effort some time. There’s nothing else like it anywhere north of Hayward. Here’s a glimpse, looking over the upper part of the park toward the highest hills (click for 1000 pixels).


Some psychologists say that land like this hits a deep, atavistic spot in the brain that’s tuned to our ancestry in Africa. It’s worth testing that hypothesis for yourself.

The Friends of Knowland Park are fiercely protective of this land, but one thing they don’t mention is that much of it is underlain by Franciscan melange, unlike anywhere else on this side of the Hayward fault. We’re looking at it—and see here on the right-hand side: a big old outcrop.


I can’t wait to visit it.


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