Archive for the ‘Oakland geology views’ Category

An early look at the Fan

4 September 2017

Lots of people love old photographs of familiar places, or old landmarks when they were new. I love old photos of Oakland because they show the land before it was paved over and/or forested.

The early California photographer Carleton Watkins was instrumental in saving Yosemite as a public park, simply because his large-scale images let people see its beauty and grandeur for themselves. But he also practiced his trade up and down the Pacific coast, including Oakland.

Here’s a stereograph he made here in 1876, looking east from the roof of the Grand Central Hotel at 12th and Webster. Click it to see its full 1000-pixel size.

Stereographs were made to be viewed through a simple apparatus that allows you to see a 3D image. You can do it without a viewer if you cross your eyes carefully. (Don’t worry if you can’t; you’re like most people.) To simplify things, I’ve turned one of the images into black and white and zoomed in a bit (800 px).

This is a pretty good image of Oakland’s high hills, the highest of which is Redwood Peak at the left edge. Lake Merritt sits between downtown and the hills of old Brooklyn. That hook in the shoreline is the cove where Wesley Avenue splits from Lakeshore Avenue today, heading left up a little valley. The right edge of the photo is where East 18th Street meets Lakeshore.

Between Redwood Peak and the shore of Lake Merritt, the top one-third is the high hills and the bottom third is the low hills. The middle third, hard to see, is the rocky hills above Piedmont and their eastern continuation in Oakmore and Redwood Heights.

Note that almost all of this is treeless. That was the state of the whole East Bay when the Spanish and the Americans came here. The exception was the redwood groves, which occupied the highest part of the ridgeline until they were logged out before 1860, and the coastal oak groves nearer the bay.

Anyway, what caught my eye in this photo was its view of the undeveloped lower hills that are almost totally hidden by houses today. Those hills were overridden first by wealthy estates, then by homes and apartments whose selling point was their views. To me, the real view was what those structures wiped out. Today only three bits of that terrain are left: San Antonio Park, Home of Peace Cemetery and Evergreen Cemetery.

Here’s how the Fan fits into that view. We’re looking east across lobe 4, the central segment of this ancient alluvial fan that dominates central Oakland.

Today, you can walk all over those hills and picture how they would have looked before development, but it’s a struggle. The old photographs are indispensible, and precious.

Advertisements

South Dunsmuir Ridge

29 May 2017

I finally got to a sweet corner of town last week, the sunny side of Dunsmuir Ridge, this lovely hill in the Google Maps 3D view.

The view is to the north-northwest, such that the Hayward fault runs straight up about a thumb’s width from the left edge. The maps below start with the 1915 topo map, in which the ridge’s top is the lobed outline of the 625-foot contour.

That straight creek valley along the hill’s south side — the gorge in the foreground of the top image — keeps catching my eye, but it seems to be inaccessible, which might make it Oakland’s wildest piece of land. The watershed map below may help in visualizing the hill and its surroundings. The two black dots are where the fire trail I took starts and ends.

Dunsmuir Ridge is city land, rescued from development after several aborted attempts to put high-end estates on this broad hilltop overlooking (in both senses) the deadly Hayward fault. The fire trail starts at the end of Cranford Way and winds up the ridge to join the fire road from the other side, which I’ve featured here before.

The walk is very scenic. To the north, downtown rises against Mount Tam.

Or if you prefer, there’s the new profile of San Francisco.

Higher up, the view opens out. Here San Leandro Creek is made visible as a line of trees coming out of the canyon toward its mouth near the airport.

But the main attraction is to the south. This is the best place to take portraits of Fairmont Ridge and its quarry scar. Unlike most places, this trail sets off the hill with a foreground of wild, forested land.

The prominent cleared space midway up the trail — a staging pad for firefighters — has regular visitors who find the spot special.

Interestingly, this spot is mapped as a patch of the peculiar Irvington-aged gravel that first brought me to Dunsmuir Ridge in 2009. However, I didn’t notice much of it, if any. See it on the geologic map — the white dots mark the ends of the fire trail.

There are rocks to be seen too. The soil is thin in most places. This little cut displays a profile of the soil and the decaying bedrock — saprolite — just beneath it.

The bedrock varies, and it doesn’t match the geologic map very closely. I would say nearly all of the lower part is not Leona volcanics (Jsv) but San Leandro Gabbro (gb). It has the gabbro’s pepper-and-salt appearance but is stained orange instead of the pristine rock’s bluish gray (as I saw earlier that day in San Leandro). You’ll see it well exposed in the trail itself, where this winter’s heavy rains carved fresh runnels.

If the city fills them before you get there (which it should before they become gullies), there are still roadside exposures that display the rock well, and it’s unmistakably gabbro where the map says volcanics. The top of the hill, though, is unquestionably Leona volcanics.

My long-term plan is to revisit every bit of bedrock in Oakland and log it. Besides sheer nerdery and the chance to improve the map, my motive is to come back to views like this one over and over again.

The old quarry is still for sale. Developers have tried to put houses there, but they keep getting shot down. Better, I say, for the Regional Parks District to acquire the land and develop it for quiet recreation.

Mountain View Cemetery: The Bay area’s best landscape

1 May 2017

Although I’m tempted just to let the photos in this post stand on their own, let me make a case that Mountain View Cemetery offers the best landscape in the Bay area.

First there’s the cemetery itself. The managers have been putting a lot of effort into improving the ground — see the excellent new stonework and gravel path in the first photo — and this winter’s abundant rainfall has abetted it by giving the hills a coat of green that ought to last longer than usual before turning gold, then brown.

Unlike your typical cemetery, Mountain View is very large and occupies the rolling terrain of the Piedmont block, consisting of Franciscan melange. In the photo below, all of the land in sight lies within the cemetery’s property.

Long ago the operators arranged for Cemetery Creek (headwaters of Glen Echo Creek) to fill three ponds, where the water can be parceled out over the dry season to help keep the turf lush. Right now they’re brim full and support a few waterfowl. The open hilltop on the left side will be turned into a new section of graves under a proposed plan.

The Franciscan outcrops or “knockers” in the cemetery’s hills echo the finished stone displayed so touchingly in the grave markers. Many historical Oaklanders famous and obscure rest here. A random walk in any direction will bring up names that ring a bell if you’ve spent significant time in the East Bay. Yes, that’s what cemeteries are for, but without the graves this territory would be just another busy park. The dead ensure that the living visitors stay on their best behavior.

And this is important — the delights of the cemetery don’t stop at its edge. The east side has had its huge hedge of overgrown eucalyptus removed, opening the crest of the high hills and the well-tended neighborhoods of Broadway Terrace to view.

A few eucalyptus trees remain on the hilltop hosting the cemetery’s high staging area. In manageable numbers, their trunks are attractive as they frame views of tempting places.

With the view east restored, there’s now a postcard vista in every direction you look. To the west you can see the Golden Gate, San Francisco, St. Mary’s Cemetery and Oakland’s outer harbor.

To the southwest is downtown Oakland and the ridges of the San Mateo Peninsula. These views, as well as those to the north and south, will always be unspoiled. From Mountain View, one can take in surroundings that encompass a large share of the greater Bay area from the midst of a setting that’s both attractive and historic.

So that’s my main case for this being the Bay area’s best landscape. But there’s more — there are rocks. I always make sure to visit this outcrop of red-brown radiolarian chert on the hillside behind the garden mausoleum, plot 3.

Other parts of the cemetery consist of shale, like this bit left behind from an excavation in plot 9.

The road up to the top of the cemetery exposes some of the well-bedded mudstone that underlies much of the grounds, but look in the gutter for the freshest exposure.

And once up there, make your way bayward from the northern tip of plot 77 to this outcrop of green and red chert.

I’m glad to entertain arguments that one place or another might be superior to our cemetery. For sheer viewshed, Mount Diablo is a candidate, as is Tamalpais. Twin Peaks in San Francisco gives excellent views of Oakland. Mount Livermore, on Angel Island, is worth a special mention. The South Bay and North Bay have many more picturesque places, not to mention the Peninsula. Lots of these spots survey a more spacious territory, but Mountain View surveys the most gracious territory, a viewshed of singular integrity that extends from infinity to your feet. In a region full of landscapes, this one offers as much elegance as it does grandeur.