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.