Archive for the ‘oakland stone’ Category

Rocks of the Crusher Quarry

11 April 2015

This former quarry in Laundry Farm encompassed the ground now occupied by Belfast and Bermuda Avenues, just south of Horseshoe Canyon and Leona Heights Park. One source, the Laundry Farm map, shows something called the Hotel Mine in this area but I have found nothing about that mine, only information about the Crusher Quarry. It was operated by the E. B. & A. L. Stone Company around the turn of the last century.

Here’s where we start, at this fire road just north of Bermuda Avenue off Mountain Boulevard.


The square object is the upturned west end of a long, arcing concrete ramp. It slopes down to ground level and levels off beneath some oak trees.


Then it turns up again, as if aiming at the old quarry face.


Here’s the broken upper end.


This was once the working middle part of a cable tramway, a set of steel cables that carried huge buckets back and forth between the rock face and the crusher. The ramp therefore describes a roughly catenary curve corresponding to the natural sag in the cables.

Onward to the high working face of the quarry.


This is highly fractured “Leona rhyolite” that needed little processing because it was already naturally half-crushed. The name of the quarry may be typical 19th-century American irony.


The stone has acquired a typical blushing orange hue because it releases a lot of iron, which oxidizes and hydrates forming thin crusts on exposed surfaces. I think that the notable deposits of red and yellow ocher in this area, which were widely known among Bay Area native tribes, arose from many thousands of years of uplift, fracture and weathering of this rock.


Higher on the hillside above the quarry, you can find lots of natural outcrops. They show signs of working in places. I think the stone has a nice presence.


You’ll see sheltered spots with the glimmer of various shades of ocher; also evidence of wildlife.


On the way back out, take time to see what’s blooming in the raw land the quarry left behind. These are called red maids.


And the fine gravel even supports an underground ecosystem that produced this emerging mushroom.


The locals enjoy and watch this place, so there isn’t any tagging or bottle-smashing to speak of. Climbing is dangerous; stick to Berkeley’s rock parks for that. Visit discreetly and leave the place cleaner than it was when you came.

Some East Oakland stones

31 January 2015

Oakland’s rocks aren’t all in the ground. They’re in our yards and homes, too. Here are a few presented in the order I found them lately.

There’s a house on 60th Avenue that stopped me in my tracks, its walls studded with stones. A neighbor down the block told me “Oh yes, those are wonderful! We looked at that house when we were buying in this neighborhood. The owner’s daughter runs a preschool across the way.” Click that one for an 1100-pixel version.


A few weeks later I visited Best Avenue, high in Maxwell Park, and was arrested by the front yard here. Sometimes rocks, like people, look best with painted faces.


A block away is another property treated by the same decorator.


And just yesterday this basket of painted stones seized me by the eyes. It’s at the Free Oakland UP gallery and workshop, in the Loard’s plaza at Coolidge and MacArthur.


Our local fill

23 December 2014

There’s a little corner of Lake Merritt that the improvers haven’t gotten around to, on the north shore by the pergola. Here the concrete walkway gives way to a stretch of old fill.


The original wetland that became Lake Merritt was known as San Antonio Slough. From Oakland’s earliest days, the locals kept trying to “reclaim” it by turning it into dry land, just as they did all around the bay. The whole waterfront is reclaimed land. The basic technique was to haul dirt and rock and rubbish down to the water, shove it in and tamp it down. In Gold Rush San Francisco they’d use abandoned ships for fill, but Oakland’s founding fathers had advanced beyond such crude strategems.

Some of this material came from the holes dug for building foundations, but it also came from quarries in the local hills ranging in size from little borrow pits to big enterprises like the Blair Quarry (now Dracena Park) in Piedmont. Not just stone, either—Oakland had abundant gravel nearby, too.

If they weren’t trying to fill it in, the makers of Lake Merritt were trying to elevate its mucky shoreline and civilize it. The rocks in this part of Lake Merritt appear to be good old Franciscan chert, possibly from the “phthanite” diggings that Walter Blair exploited in today’s Moraga Canyon. It made quality fill, hard and clean and compact. I don’t know how long it will stay visible as we continue to civilize the lakeshore. Visit it some time when you’re on a walk around the lake and the ground is washed clean. The more we kick it and scuff it and curse it for stubbing our toes, the more its polish gleams.


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