Archive for the ‘oakland geology views’ Category

Haddon Hill from Ivy Hill

29 April 2012

Ivy Hill is a small but distinct lobe of the big Pleistocene alluvial fan of central Oakland, a wedge between Park Boulevard and 8th Avenue bounded on the west by East 18th Street. This view is from nearly at its high point, at East 21st Street and 7th Avenue, looking at and over Haddon Hill.

haddon hill

Click the photo for a 1150-pixel version. The tall trees beyond the telephone pole are in Smith Park, on Park Boulevard, at the foot of Haddon Hill. Beyond the hill are a whole bunch of buildings on the other side of Lake Merritt. Left of the light pole are the Elihu Harris building and City Hall; to their right is the heart of downtown with Mount Tam behind and the blue glass face of One Lakeside in front. Right of the telephone pole is the Kaiser Center buildings and St. Paul’s Tower behind the street trees. The dark tower on the right is the ugly place by the lake. Clustered at the right are the Bellevue-Staten Building, on the lake, and two buildings all the way over on Pill Hill.

Haddon Hill

22 April 2012

Lately I’ve been walking on the part of Oakland underlain by the large Pleistocene alluvial fan (see the city geologic map). As I go, I mentally map it into separate entities, and one of them is Haddon Hill, bounded by the lake, 580 and Park Boulevard. In the past I only saw the hill from the lake, as in this shot from New Year’s Day 2007.

haddon hill

The west face of the hill, seen here, is quite steep. The opposite side of the hill slopes more gently down to the valley of Park Boulevard, and then the opposite side of Park is also quite steep. That doesn’t seem to be a general pattern, but it is curious. The photo below is taken from across Park, at 7th Avenue and Ivy Drive, and looks up Spruce Street to the highest point on the hill, where the St. Vartan Armenian Church sits.

haddon hill

The elevation there is about 180 feet. That doesn’t sound like much, but the ground around it is low and it can feel like a trek on foot. The hilltop area has views much grander than you would think, but they’re hard to photograph.

haddon hill view

The topo map shows that the hill extends across 580 a little bit, where Alma Place is. The real edge of the hill, then, would be Indian Gulch (Trestle Glen).

Lift up your eyes

26 March 2012

One thing I love about the hills is that they grace every part of Oakland, even the plainest, most utilitarian parts of town, like Peralta Street. You don’t have to be riding BART or high on a freeway or in a park to enjoy the hills, just out and about.

peralta street

And those parts of town, in turn, don’t hold back. They get in your face and don’t pretend to be someplace else.

do something positive

Those parts of town help keep me honest. I recommend them.

Clinton terrace

29 February 2012

Oakland has some small areas mapped as marine terraces. They run about 20 to 40 feet above sea level and they’re very flat. Here’s a look down 5th Avenue toward the bay that shows the terrace well, beyond the dip in the road. I was standing at E. 20th Street, on the Pleistocene fan; the low point in the road is at E. 18th Street.

clinton terrace

I name it Clinton terrace because it underlies the former town of Clinton. The terrace runs along the foot of the fan as far as Fruitvale. Here it is on the geologic map, unit Qmt, “Quaternary marine terrace deposits (Pleistocene).” I was standing at the asterisk.

clinton terrace map

In the map description, Russ Graymer correlates this terrace with other terraces along San Pablo Bay at Lone Tree Point and Wilson Point. Those have been dated at about 125,000 years old using uranium-thorium dating of oyster shells. That time was a well-known highstand of sea level, and coeval terraces occur up and down the Pacific coast. So we imagine the bay waves lapping against the older alluvial fan, nibbling off sediment and spreading it around to build a nice flat terrace. It was probably a lovely tidal marsh until the glaciers resumed, the sea fell and land vegetation moved in. Later, creeks dug into it along Park Boulevard, 14th Avenue and 23rd Avenue.

You can see there’s a bit more of the terrace under Lakeside Park. A final piece underlies the Valdez Street area beyond the upper left corner.

Gudde Ridge

19 February 2012

The basalt of the Moraga Formation is spectacularly exposed on both sides of Route 24 east of the Caldecott Tunnel. From along the highway you can get an excellent view of its makeup and structure, but this view from Radio Tower Hill shows how the rock unit makes up Gudde Ridge.

gudde ridge

Click the photo for the 1000-pixel verson. Gudde Ridge runs just east of Round Top all the way down to Canyon Road, on the back side of Moraga. The town of Canyon is on its west flank. And it’s Moraga basalt the whole way. In this photo you can see the underlying Orinda Formation to the right of the basalt. It’s gray conglomerate as opposed to the red-brown basalt.

Home from afar

5 February 2012

A few weeks ago I paid a visit to distant Mount Vaca, north of Fairfield on the Solano-Napa County line. It’s almost 3000 feet up and commands a wide view. Naturally I looked back at the Oakland Hills. There they were, immediately recognizable.

view from Blue Ridge

Click the photo for a 950-pixel version. In the upper center is Round Top, with Redwood Peak to the left and Vollmer, then Grizzly Peak to the right. Behind them is San Bruno Mountain across the bay. On the left edge are the plumes from the Avon refinery near Martinez and a bit of the Delta. The entire vista is part of the plate boundary, cut into slivers by the strands of the San Andreas fault system. At geological speed, they are all moving rightward at various rates measured in millimeters per year.

I’m working on my talk for the Oakland Heritage Alliance, this Thursday at 7:00. The process is forcing me back away from the details and toward the big picture—not the geological big picture, but the picture nongeologists see. That means I talk less about plate boundaries and more about how to live on our particular one.

Radio Tower Hill

20 January 2012

On Tuesday the skies were so clear I made a point of visiting the hills. Not as clear as Monday, but from the top of Radio Tower Hill this is how the Golden Gate looked. Remember this when the weather is dismal.

golden gate from radio tower hill

Click the photo for a 1000-pixel version. That’s the Farallon Islands on the horizon, perched at the edge of the continental shelf on the Pacific plate. They consist of the same granite found on Point Reyes, Bodega Head, Montara Mountain and points south in the Salinian terrane. The blob just below them is a freighter bound for the Port of Oakland, or perhaps a tanker bound for Point Richmond. Downward in the image is the bridge, Alcatraz Island, Treasure Island and the foot of Ashby Avenue in Berkeley.

Radio Tower Hill doesn’t really have a name. It’s the hill at the intersection of Grizzly Peak Boulevard and Marlborough Terrace. It’s made of Claremont chert.


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