DryStoneGarden

Sold! To the person with a giant backhoe...

One of the fun parts about backcountry rock work is searching around to find the rocks to build with. One of the most laborious parts is then moving the chosen rocks to the building site. Some wilderness crews use a come-along or grip hoist, but most do it with human power, rolling the rocks downhill to the trail with their hands or with a six-foot long rockbar. Here are a few backcountry sayings, born of many hours of wrestling against gravity:

Skidding is better than rolling, rolling is better than lifting, lifting sucks.

Stones come in three sizes: hernia, double-hernia, and too small.

If you can carry it, it’s too small.

mallorcan style wall

Posting about the angled stone wall in this year’s garden show seems like a good excuse to post about the Mallorcan style wall we did with Mariposa Gardening and Design in the show last year. It’s not as eye-catching as the angled stone, but the building style is unique in its own way. Personally, I didn’t lay a single stone on the wall–I was a bit skeptical about building a wall and then taking it apart five days later, part of the reason I like stone is that it is the longest-lasting building material on earth, so instead my contribution to the garden was flagstone steps that I could afterwards re-install in a real garden–but it was a nice wall and it deserves to have some internet presence.  A lot of the stuff in the garden show is just facade work, but the crew built a real wall, thirteen tons worth, pretty cool and pretty crazy.

Mallorcan walls are also sometimes called polygonal walls because they use five-sided stones laid in an arch pattern; traditional walls use four-sided rectangular stones laid in linear courses. One of the sacred rules of traditional walls is to break every joint, but with a polygonal wall the joints zigzag enough that the rule doesn’t apply. Instead, the rule for a polygonal wall is to have every stone touched by five others. Instead of trying to create a flat surface for the next stone, you try to make a cradle for it, and instead of vertical and horizontal lines, you create arches. The idea is that the adjoining stones form an arch around any given stone, so if that stone falls out the other stones will still hold together and the wall won’t fail. In theory, if you pick a stone, you can see a little arch of other stones around it.

mallorcan wall arch detail

The walling style is really effective at making tall, strong, long-lasting walls out of irregular stone. Mallorca is full of walls hundreds of years old, and examples I’ve seen on the internet are often ten or twenty feet tall. To work on the walls, workers pound metal bars between the stones and then put boards across the bars to act as scaffolding. A lot of the walls are pretty rough looking but at the same time really appealing because of their size and strength. The walls get capped with European-style vertical coping stones, which adds a nice touch of style and self-consciousness to the rather rough, naturalistic stonework. Our wall in the garden show was made with Napa basalt, the closest Bay Area equivalent to the limestone they have in Mallorca.

The Stone Foundation has a beautiful Mallorcan wall in their write-up for the 2007 workshop and another in their write-up for the upcoming 2009 one. DryStoneWalling has photos of two walls, one that’s retaining and one that’s freestanding. Below, I put one of my sets of flagstone steps with a section of Mallorcan cheek wall.

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Old Town Patio Stone

I wanted to post a few more photos of the freestanding wall from the garden show. I haven’t seen many walls with the courses running at an angle, and none quite like this one. To lay the stones at an angle goes against the “rules” I learned about building walls, but, apparently, stoneworkers have been doing it in Cornwall for centuries. The Cornish call their walls “hedges”, and do things like cover them with sod, and they have a whole tradition of stacking slate vertically or at an angle. Their slate doesn’t support weight well when stacked horizontally, so they turn it on its edge, which makes a certain amount of sense; I’ve worked with slate which would crumble from a single hammer blow across the flat, but could withstand repeated blows against the narrow edge. The Guild of Cornish Hedgers has a collection of photos including some walls built with a herringbone pattern. I particularly like this one with stiles for climbing over it. There’s a photo on a blog here and another photo in the Cornish collection in the Dry Stone Walling Association of Great Britain gallery.

the courses, with my camera rotated

Through the magic of turning the camera sideways, you can see that the wall is built with courses like a traditional wall, just that the courses run at an angle.

transition from traditional to angled

The horizontally laid stones of the arch set the angle for the slanted courses. A lot of the wall’s weight is going to be pushing against those horizontal courses and against that arch, but arches are strong and the wall could have stood for a lot longer than the five days of the garden show. Now it only exists in memories and photos.

The Dry Stone Walling Association of Canada has more photos of the wall on their site, and photos of another angled wall they built for a garden show in Canada last year.

WallsWithoutMortar has photos of another angled wall built in Danville, here.

I stuck a couple of detail photos of the arch below. (more…)

Big Springs Stone Table

It’s not quite April, but we already feel safe to move our cushions outside and get our front porch ready for summer. The table on our porch is new for us this year, assembled from a slab and a block of granite. The stone’s called Big Springs, from somewhere in Utah, boulders cut into slices that are perfect for tables and benches. The stone has a beautiful grain, as if it were wood, and the sides have bluish and yellowish lichen. This table didn’t take any skill to assemble; I just put the flat stone on the flat-topped granite block. It didn’t need mortar or even a shim. The slabs aren’t particularly expensive, so I don’t understand why they aren’t more common. Doesn’t everyone want a three-hundred pound bistro table?

There’s another photo showing the grain of the stone below. (more…)

I’m hoping this photo from last fall will sell my Mom on some gravel. She’s been resistant to the idea of using gravel in her yard, but I think she’s picturing gray construction gravel. I probably need to start calling it Tuscany Gold, the way they do at the stoneyard, make it sound more stylish. The Tuscany Gold looks a bit mediterranean/southwestern for her taste, but gravel has some advantages over flagstone, mainly that it drains well and it’s inexpensive and easy to install and maintain. It’s not so good for patio furniture, it’s not as nice to walk on, and it can get stuck in the soles of your shoes and scratch the hardwood floors, but none of those issues would be a problem for that section of my parents’ yard where they want to take out some lawn. And I think the ease of installation should trump everything in this instance. A mother shouldn’t want her only son carrying a ton of flagstone into the backyard.

ryan 3/4

Three Rivers Flagstone

One of our clients calls Three Rivers flagstone “purple zebra,” which is a pretty accurate description. It always catches our clients’ eyes when they visit the stoneyard, though they often balk at the price, as it became really expensive a few years ago and is probably the most expensive flagstone commonly available in the Bay Area. It’s from one of the largest flagstone quarries in the United States, located up in the Sawtooth Mountains in Idaho. The quarry wanted to expand and the Bush administration, in their inimitable way, told them to go right ahead and not worry about doing an environmental impact study. An environmental group, the Western Watersheds Project, which owned a wildlife preserve adjacent to the quarry, then sued, and a judge agreed with the environmentalists that yes, U.S. law does require environmental impact studies, and temporarily shut down work at the quarry. Everyone settled out of court and the price then went up a couple of hundred dollars to around $750/ton.

I’ve seen the stone described as a type of quartz-sandstone and as argillite. Answers.com defines argillite as “an intermediate between shale and slate, that does not possess true slaty cleavage,” which sounds about right, except that I would add that Three Rivers is really hard and heavy. (Can I say that I prefer my stone with a bit more cleavage? It’s true. Cleavage is the tendency of stone to break cleanly.) The swirls of color in Three Rivers come from irregular mineral layers which look cool but make the stone inclined to break irregularly. The patio in the photo, for instance, has rougher, wider joints than I would do with a cleaner-breaking stone like a sandstone. To get tight joints with Three Rivers, you pretty much have to cut everything with a saw. We usually only use Three Rivers for stepping stones, paths, and small patios; it can look too busy when used for larger areas.

Quarriesandbeyond.org has links to info about the Three Rivers quarry on their list of quarries in Idaho.

Three Rivers Flagstone Patio