Archive for the ‘oakland geology views’ Category

Manzanita ridge

28 April 2014

The ridge traversed by Manzanita Drive is one of Oakland’s highest residential areas, higher than 1400 feet. It’s the home-studded rise in the Oakland skyline to the right of Round Top in the blog’s banner image. Here’s the topographic view, from Google Maps:

manz-ridge-topo

. . . and here’s the matching part of the geologic map:

manz-ridge-geo

The ridge crest is held up by the Claremont Chert (Tcc), while Skyline Boulevard and Arrowhead Drive, running parallel just to its south, go through the crumbly Sobrante Formation (Tsm). (The other formations are the Orinda Formation, Tor, and the unnamed Eocene sandstone of upper Shepard Canyon, Tes.) Here’s the chert exposed at the west end of Manzanita; it and the next two photos click bigger.

Click for 800-pixel version

The views are terrific. Here’s the view north over the Huckleberry saddle to the smaller ridge of Claremont Chert that Elverton Drive skirts.

Click for 1000-pixel version

The middle of Manzanita offers fine views of Round Top.

Click for 800-pixel version

And the other end of Manzanita, past the unexpected Hills Swim & Tennis Club, is another saddle at the top of Shephard Canyon where the road to Canyon and Moraga crosses the hills.

skyline-shep-pinehurst-saddle

More than anywhere else in Oakland, this is an island in the sky.

Fruitvale Station vista

24 March 2014

Sometimes the weather is clear enough, but just hazy enough, to reveal the details of the landscape for quite some distance. A week ago the view down the line from the Fruitvale BART station looked like this.

fruitvalestationview450

I know it’s a small image, so click on it for an annotated 1000-pixel version. Most of the view extends beyond Oakland city limits. The farthest peaks are in the Ohlone Wilderness east of San Jose, some 30 miles away. Once you become familiar with our skyline, it’s never boring.

Lower Colton

31 January 2014

You may think of Snake Road as the ridge road that climbs the crest between Thornhill and Shepherd canyons, but it’s really Colton Boulevard. For a quiet hike above Montclair with views, you want Colton. Its lower part runs north of Snake across ground underlain by the Redwood Canyon Formation. Here’s a roadside outcrop.

colton-Kr

I didn’t even notice the parallel fractures until I opened the photo at home. They probably represent a bit of extra cementation, thanks to a late pulse of fluids, but they may also be original bedding.

I mentioned views. If you loop around Mendoza and Mazuela Drives you can view some immaculate houses and grounds, but I like the big empty lot on Mazuela that overlooks Pinehaven canyon; click it for the bigger version.

mazuelaview450

Huckleberry saddle

18 November 2013

The entrance to Huckleberry Botanic Regional Preserve is at a low point in the spine of the Oakland Hills, where the steep eastern arm of Thornhill canyon has cut headward toward the equally steep canyon of San Leandro Creek. Both canyons are steep because the rock between them is the tough Claremont chert. The saddle between the two canyons provides good views to the west and east, and a little path (labeled Huckleberry Path on the map) leads north from the Huckleberry entrance, a private entrance to the preserve for the residents of Elverton Drive. That’s where I got these pictures, first looking southwest toward downtown:

elvrtn-lakemerit

and due west, over the opposite wall of Thornhill canyon, toward the Golden Gate.

elvrtn-ggate

Turn around, and it’s just a few steps to find these views of the Las Trampas Ridge area—

elvrtn-trampas

—and Mount Diablo, which never ceases to surprise me when I see it from Oakland. I think of Diablo as a whole different domain, reachable only by a drive through the tunnel and not visible west of Lafayette. But here it is, looking downright neighborly.

elvrtn-diablo

Only a few Oaklanders get to see the view east; we’re a westward-leaning city.

The Oakmore block

7 November 2013

The Oakmore district is quite a distinct part of town. Here’s how its geology makes it so. I’ll call it the Oakmore block, although that’s a bit of a misnomer—it’s the eastern end of the Piedmont block.

oakmore-geomap

The neighborhood is defined by the light blue of Franciscan sandstone of the Novato Quarry terrane, bounded by three canyons. The canyon on the northeast side is occupied by Route 13, of course, which corresponds to the Hayward fault. Here’s the view across it, looking east from the easternmost corner of the Oakmore block (the end of Braemar Road) to Joaquin Miller Park. The top of the grassy slope is the overlook at Lookout Point.

joaquinview

Dimond Canyon on the west is the most dramatic boundary, but the bedrock is the same on both sides; there is some accident of geologic history that has maintained this deep streamcut. Leimert Boulevard defines that side of the neighborhood. Roadcuts about midway up Leimert expose a lot of strong sandstone like this.

leimertcrop

And on the southeast is an unsung stream valley cut along the edge of the Piedmont block. Whittle creek, I guess I’d call it, because Whittle Avenue runs up it, and the Head-Royce School is nestled in it. The valley grows into a nice amphitheater at its head. This is the view from there—the end of Melvin Road—across to the Greek cathedral and Mormon temple. Lincoln Avenue is the ridge road on the other side of this valley.

oakmore-temples

Over here I see more shaly bedrock, like this stuff exposed on uppermost Fruitvale Avenue . . .

oakmore-shale

. . . and bit more structure here where Wrenn Street meets Hoover Avenue.

oakmore-wrenn-hoover

All of this is expected in the Franciscan. The odd bit I haven’t figured out is near the end of Melvin, which looks to the naked eye like a volcaniclastic rock. Perhaps the boundary on the geologic map is a little off.

oakmore-volc

All I know is that when you take your eyes off the ground and look off toward the Bay, Oakmore is a mighty fine place.

oakmore-view

I don’t know exactly where the realtors put the southern line, but the dotted-line contact running from Sausal Creek along Whittle, marking the hidden thrust fault at the edge of the hills and the bedrock alike, works for me.

Lakeside Park terrace

1 September 2013

Lakeside Park is one of the most parklike parks I know. Perhaps I feel this way because I imprinted on it at kindergarten age.

Click for larger photo

Youthful feelings aside, I think that geology makes the park this way: it’s set on the late Pleistocene marine terrace, planed and beveled by the sea waves during an interglacial highstand approximately 125,000 years ago. The planar setting, studded with trees to the limits of vision, suggests a vision of infinity, or at least limitlessness.

This spot is in front of Children’s Fairyland, where young children then and now can experience mind-blowing things everywhere they look. Show them these rocks, too: they’re ochre-stone and chert from our own hills.

Foothill’s foot

6 August 2013

Foothill Boulevard descends to Lake Merritt in this gentle slope down from the old marine terrace (Clinton terrace).

foothillfoot

For a mile and half east from here, Foothill runs along the terrace. East of 14th Avenue, where it’s a two-way street, it skirts the steep edge of the Fan at San Antonio hill where the contrast between the two geologic units is most dramatic.


Follow

Get every new post delivered to your Inbox.

Join 3,854 other followers