Archive for the ‘oakland geology walks’ Category

Northern Upper Rockridge walk (#30)

27 January 2013

Walk number 30 in Charles Fleming’s Secret Stairs East Bay, which he refers to as upper Rockridge west, goes from the Rockridge BART station over the Franciscan bedrock hills of upper Rockridge. The views are great, and there are a few rocks as well.

Here’s the route map (click it for a larger version).


And here’s the route shown on the geologic map. It goes counterclockwise.


The orange Qpaf is old alluvial terrace, KJfm is Franciscan melange, and fg is Franciscan greenstone (you might see a little of that near the end if you’re vigilant). Melange is lumpy stuff, as I’ve said before, mostly shale with knockers of harder rocks here and there.

And here’s the topography, with the sites of the following photos marked on it. The walk basically circles the bowl cradling little Rockridge Park with a couple of forays over its rim.


The new parklet at the BART station is nice. Naturally the boulders were sourced elsewhere.


The first part of the walk is housewatching until you cross Broadway to Rockridge Boulevard, where you face the hills through an allee of big palms. We’re at the 200-foot contour and looking at homes above 400 feet. It’s steep land, but not as bad as the high hills.


Once you get up into the hills, you get views in all directions. Pick a good clear day to do this walk.


As you go along Acacia Avenue, keep an eye out for Cactus Rock, reputed to be The Rock that gave Rockridge its name. I’m not fully sure that’s true, but I’m at a dead end in that quest at the moment.


The high point of the walk is on Alpine Terrace, at about 450 feet. It has several empty lots left over from the 1991 Hills Fire. This one always gives me a qualm.


The top of the elaborate Brookside Steps features this gnarly boulder, which I’ve featured here before. This is what they should have used down at the BART station.


As you wander over to the north end of the loop, enjoy the views that way. Here we have the chaparral of Claremont Canyon, the homes of the Claremont Hills neighborhood, and in front the solar roof of the College Prep School, which I was pleased to see produced a finalist in the Intel Science Talent Search this year. That is a huge brag for Oakland.


Here’s a view of upper Hiller Highlands, including one of the two big round houses up there. This is the lower one, at the end of Devon Court.


And here’s the view east toward the eastern, higher crest of upper Rockridge studded with homes. A glimpse of uppermost Broadway Terrace is at left. All the distant points in these last three photos are across the Hayward fault.


The long, sturdy stairway was constructed by Schnoor & Son. By my reckoning, that makes this 100 years old. Other sidewalk stamps up here date from 1913.


We’re finally going back down in to the bowl of Rockridge Boulevard, so you can see now what those high homes have for views—straight out the Golden Gate. The good burghers who settled this area a century ago would take these steps to catch the streetcar to their jobs across the bay.


Here’s the view of Claremont Canyon from Broadway and Keith. The white bit by the traffic light is the tower of the Claremont Resort. The nearer ridge is just in Berkeley across the valley of Temescal Creek.


And from here it’s a straight walk down to the refreshments of College Avenue. There are bits of bedrock along the upper part of Keith, but then you’re back to the lowlands.

Lakeshore ridges walk (#26)

31 December 2012

Walk number 26 in Charles Fleming’s Secret Stairs East Bay traverses Longridge and its neighbor Calmar ridge, sticking to the paths and stairways. It doesn’t really give you the full experience of the ridges themselves (I plan to make posts for each), but it’s still fun to learn the local shortcuts. Here’s the route map on Google Maps terrain.


You can see that Longridge Road and Calmar Avenue are both ridge roads, which are especially desirable for developers and homeowners because everyone gets a great view unless the downhill neighbors decide to plant redwoods here, where the habitat is wrong.

The geologic map shows that essentially all the route is in the Pleistocene alluvial fan or, as I’m starting to think of it, the Fan.


The walk starts at the fine iron gateposts at the foot of Longridge Road. Locations of these photos are noted on the geologic map.


You ascend the ridge along its gently but persistently sloping crest, then sidestep into the private Oak Grove Park along its northern flank. The view here gives a glimpse of Mandana valley, between the two ridges, and the high spine of the Oakland Hills.


Most of the path is quite secluded, though. This entire neighborhood started out as grassland, like most of Oakland.


At the other end of the park is steep Paloma Avenue, providing good views of Calmar ridge across Mandana valley.


And here’s Mandana Boulevard, running down the floor of its stream valley. The creek here is entirely culverted and appears never to have merited its own name, probably because it was seasonal.


Now comes the hardcore stairway portion of the walk, straight up the flank of Calmar ridge and over its top down to Balfour Avenue, shown here. The stairway here is quite hinky, which distracts from the view of Grizzly Peak over the north end of the Piedmont bedrock block.


Another stairway takes you down to Walavista Avenue, running up its own valley. At the street’s upper end you hop over a subtle divide into the valley of a tributary to Wildwood Creek, traversed by a quiet, funky little path that butts onto another path connecting Carlston and Portal avenues as a continuation of Santa Ray Avenue. In 1912, this valley was a Key Route line.


You take the right hook onto Carlston and back down across Mandana valley, ready to climb Longridge again. The little pocket park across Mandana, on the right, is a good place to kick back on a bench.


The route takes a jog along Paramount Road, which happens to occupy the crest of the ridge here while Longridge Road is a little off to the side of its namesake. At the far end of Paramount, where the Fan leaves off and the Piedmont block begins, the terrain starts to change and Longridge peters out as a proper ridge. Right on the geologic line is the Crocker Highlands Elementary School.

From here the route goes along the south slope of Longridge and its stairways. This is part of the Trestle Glen neighborhood, but I don’t think of it as part of the glen itself, that is, Indian Gulch. Keep an eye out for views like this, from Longridge Road near the end of the walk.


Winter is a good time to take this walk, while the leaves are down. Here’s the detailed route map (click it to see full size).


Fleming calls this walk “Trestle Glen and Lakeshore Highlands.” The part of this neighborhood north of Mandana was developed as East Piedmont Heights.


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