After two ferns died in the shade of an evergreen oak, we are replacing them with currants. The coast live oak (quercus agrifola) doesn’t like summer water and creates deep shade all year, a difficult site for nearby plants. Last winter we pruned a nearby currant and used the cuttings to start replacing the ferns.
Shown above, the two new currants (ribes sanguineum glutinosum ‘White Icicle’) are to the left of the surviving giant chain fern (woodwardia fimbriata), and they’re all within the drip line of the coast live oak in the background. The evergreen oak provides shade all year, and the currants and fern are on the north side of a solid fence, where they get little direct sun. This spot has deep shade and restricted water (to protect the oak tree from oak root fungus). We live in the San Francisco Bay Area; the fern and oak are California natives.
Planted twelve years ago, our California native plant garden is fairly mature where we’re only making incremental changes. The first part of this post shows our decision process to replace the ferns: problem statement, issues, alternatives considered, the selected alternative, and progress in implementing the alternative. Second, we chose to replace the ferns using cuttings from a currant, so the post concludes with a description of hardwood propagation and progress after five months.
Continue reading Currants for a Shady Spot
In late June as the California polypody goes into summer dormancy, most fronds have fallen, but the last few fronds are still standing.
A California native plant, the California polypody (polypodium californicum) weathers the dry summers of our Mediterranean climate by going dormant in June and emerging in September.
Completed in 1892, the Searsville Dam sits astride San Francisquito Creek, which connects watershed in the mountains above Silicon Valley to the San Francisco Bay. Sedimentation has “reduced the reservoir to 10 percent of its original capacity“. At this rate, the reservoir will completely fill in 15 years, and then, sediment would wash over the dam, through the creek, and into the bay. This old dam and silted-up reservoir pose both a threat and an opportunity for the Bay Area: sediment washing down the creek returns an age-old flood threat to downstream communities like Palo Alto and Menlo Park; one reservoir of sediment is a potential source of mud needed to help save the South Bay from sea-level rise.
Sediment washing over a completely filled dam could clog the creek and lead to flooding. Floods aren’t new to the alluvial Santa Clara Valley. Resting on up to 1,500 feet of sediment, the valley floor is broad and flat because of past floods deposited sediment across the valley. The Bay Area was thinly settled when the dam was built in 1892. Since then, Silicon Valley homes and offices have been built next to the creek, limiting flood control options.
In addition to flood risk from the creek, the Bay Area has a long shoreline that is at risk from rising seas. “Back in June 2016, Bay Area voters approved Measure AA to raise $500 million to pay for wetlands restoration, flood control and wildlife projects around San Francisco Bay.” But to protect the Bay Area, the structures will need more mud than is available, per the Scientific American post.
Searsville Dam holds “approximately 2.7 million cubic yards of sediment that has built up behind the dam since its construction in 1892“. This sediment is a potential source of mud for the Bay.
Finally, Searsville Dam filling with sediment illustrates that a dam has a limited lifetime. The Bay Area is planning to build another dam. As we do this, we should consider the life-cycle costs of new dams as well as existing dams.
Continue reading Stanford’s Searsville Dam
In January I divided some purple Douglas iris plants, and yesterday I noticed the first bloom from the transplants. I had hoped for blooms this first spring. The purple flowers are more fragile than the white irises, but I admire the deep color and veins of the purple iris.
All eight transplants survived, showing that the purple irises are as hardy as the white irises. The Douglas irises (iris douglasiana) are California native plants, and they are in the shade of a coastal live oak. I used a normal lens (105 mm) with a short extension tube to get a larger photo of the flower.
After seeing the pyramids and Khufu Ship, we went for a camel ride and saw the Sphinx. This was my time being close to camels, and I had the impression that they could be temperamental, so I was a bit apprehensive.
Getting on the camel and staying on the camel is tricky. You mount the camel when it’s sitting down, which is good. But you’re sitting on a saddle on top of the camel hump, so we still have to climb up to get on the saddle.
But then, the camel has to stand up. I forget which comes first, but the camel gets up with its front legs and hind legs separately, and the camel legs are long. So when the camel rises, its body is severely tilted, and you need to lean far forward and back to stay on the camel. From the photo, you can see that it’s a long way down if you fall.
Continue reading My First Camel Ride and the Sphinx
The Khufu Ship is a large, ancient boat discovered disassembled in a pit next to the Pyramid of Cheops. “Like other buried Ancient Egyptian ships, it was apparently part of the extensive grave goods intended for use in the afterlife, and contained no bodies, unlike northern European ship burials.”
About 4,500 years old, the ship is “one of the oldest, largest, and best-preserved vessels from antiquity. It measures 43.6 m (143 ft) long and 5.9 m (19.5 ft) wide.” Khufu is another name for King Cheops.
Continue reading Khufu Ship
The Egyptian pyramids, funerary monuments to pharaohs, are incredibly old, a testament to the wealth, government, and culture of ancient Egypt. Above, the first pyramid, the Step Pyramid of Djoser, was built in the 27th century BC, 4,800 years ago. The Egyptian pyramid fields are a UNESCO World Heritage Site.
As you’ll see, the pyramids are huge and precise. Building them required a civilization with manpower, engineering, and political will. Ancient Egypt had the wealth and organization to specialize crafts and devote tremendous resources to build these tombs, at a time when the rest of the world lagged far behind.
The initial tomb design was a mastaba, which “comes from the Arabic word for a bench of mud”. A mastaba is a solid structure of mud brick. Located in a Cairo suburb, the Step Pyramid is constructed with six steps of cut stone, with each step taking the form of a mastaba on top of the earlier one. Stone is stronger than mud brick, enabling a taller and more durable structure.
Continue reading Egyptian Pyramids