The long and varied history of the hardiest landscape material

By Andy Sturdevant

April 28, 1977, seems to have been a typical news day in the Twin Cities—maybe even a little busier than usual. The front page of the next morning’s Minneapolis Tribune reported the state legislature’s approval for the creation of a stadium site committee whose ultimate decisions would, several years later, give us the Metrodome. Hard news though there was, the editors also made room for the sort of tiny, oddball local story on the front of the B section that today might take the form of a viral video. There, readers found a short photo-documentary of a natural struggle playing out on top of a bed of igneous rocks on the edge of a suburban mall parking lot.

A killdeer—or maybe a sandpiper (no one was completely certain)—was found nesting on a stretch of landscaping rocks on the periphery of the Brookdale shopping center site. When approached by curious members of the public, the bird threw itself into a dramatic fit, feigning injury and dragging itself across the stones to draw the onlookers’ attention way from the four speckled eggs it was nesting. “Survival Can Mean Putting on Act,” the headline read.

Brookdale is, of course, gone now, but you may remember the site. It was the classic Wherever-dale American shopping mall in the Victor Gruen model: a central structure in the middle of a sea of asphalt. A ubiquitous feature of these types of sites—and really, almost any postwar commercial landscape—is a few stretches of landscaping rocks, usually acting as a buffer or an interstitial space. Sometimes they lay between asphalt and grass, or automotive and pedestrian spaces, or the interior and the exterior of a place.

It’s fitting that this 40-year-old bit of natural theater should have played out on landscaping rocks. A bed of rocks is a marker of a transitional space. Killdeers thrive in these spaces, often making their nests on rock features, where their mottled eggs blend into the background. The Tribune piece notes that people routinely “walked past as close as 10 feet away,” and it didn’t seem to bother the bird. Her nest seemed well hidden.

A bed of rocks scans as organic and even soft, particularly when contrasted with harder, chillier surfaces like concrete and metal; it can serve as an intermediary between these materials and a warmer material such as brick. A plane of rocks suggests nature without explicitly mimicking specific forms that appear in nature. Better yet, it requires far less maintenance than greenery. In a markedly inorganic landscape like Brookdale in the late 1970s, that stretch of river-smoothed pebbles would have been as close to a natural landscape as you’d find between your 1976 Cutlass Supreme and the front entrance to Dayton’s. That’s undoubtedly why the killdeer chose it, and why the landscapers chose to put it there in the first place.

Rock gardens date back more than a millennium in Japan. In the 14th century, they began making use of white gravel to abstract, on a smaller and more immersive scale, the form and texture of a larger landscape—essentially, reduce them to their essence. The term ginshanada, meaning “silver sand open sea,” was introduced to describe these sweeping stretches of light-colored stone. The translation suggests a liminal zone that acts as a buffer between forms, and a space for reflection.

By the late 19th century, the use of stones and rocks had made its way into Western landscape architecture. The English botanist Reginald Farrer popularized the alpine garden, a form of rock garden that stressed a complex, methodical system for the arrangement of rocks and high-altitude plants. The ideas were first applied to private pleasure gardens, but they later appeared in public landscapes as well.

In The English Rock-Garden (1919), Farrer minted a number of best practices, warning his readers away from such lithic faux pas as “the almond pudding” (too many spiky rocks sticking up), “the dog’s grave” (a funereal landscape of flat stones), and the dreaded “Devil’s Lapful,” a free-for-all mess of rocks of all sizes and textures, the “chaotic hideousness” of which was “something to be remembered with shudders ever after.” Pay attention on your strolls through less-distinguished commercial sites and you may encounter the Devil’s Lapful.

In the U.S., landscaping rocks became a common feature in residential developments and corporate campuses after World War II, in a way that creates challenges for forward-thinking landscape architects today. “There are a lot of connotations with rock mulch,” says HGA Architects and Engineers landscape architect Theodore Lee. “There’s this residential feel to it: a kidney-shaped bed around the house and some rock mulch and shrubs. Typically, that rock is three inches,” he continues. “If you look at the projects that we do, we purposely pump the scale of the stone up to give it more presence, so it doesn’t look like the vernacular of the residential landscape.” For the new, AIA Minnesota Honor Award–winning Ramsey County Library–Shoreview (page 40), HGA used stones of three different sizes—finely crushed, crushed, and full-size boulders—for various functional and ornamental purposes.

The common stones of the postwar years, such as white quartz and black volcanic rock, signaled a shrinking, industrialized world. For the first time, rocks could be transported relatively economically across great distances. People had been digging or dynamiting into the surrounding landscape for generations and using the rock they extracted for railroad beds and gravel roads.

But there was now the possibility of integrating the geological features of distant places into local environments. A typical 1960s-era newspaper ad for wholesale and retail landscaping rocks highlighted the varieties available, a travelogue of the world’s greatest geologic hits: Texas Pink, Mexican Brown, Royal Ruby Quartz, Botticino Marble, Colorado Milky Quartz. The earliest English and American rock gardens were an attempt to transpose the romantic and unfamiliar alpine landscape of Thomas Mann’s The Magic Mountain onto familiar surroundings. By midcentury, cheaper commercial transportation and the possibility of large-scale industrial production made it possible to dramatically heighten the romanticism of even the most anodyne Midwestern landscape.

Today, the pendulum is swinging back: We want our built environment to reflect our specific somewhere, not a generalized anywhere. And the Midwestern landscape—more specifically, the rock right below it—is anything but anodyne. If you walk past newer developments with strong landscaping features, the rock you’ll see is unlikely to have been transported in from a faraway place. It’s more likely to have a regional character. Even as rock can evoke distant landscapes, it can more effectively be used to connect a site to the oldest, most elemental part of its surroundings.

“The selection of the rocks is best when it’s a rock that’s familiar to a place,” says Duluth-based architect David Salmela, FAIA, whose Honor Award–winning Deloia residence (May/June 2018 issue) has, at its heart, a central courtyard made up of wooden walkways atop a bed of crushed bluestone. “So, in Southern Minnesota, you don’t use black crushed bluestone, or mining stone from Northern Minnesota. You use something else—field stone or Kasota stone.”

“Minnesota has a strong stone legacy,” says Lee. “We have the great limestone of the southeastern part of the state, the granite of central Minnesota, the gabbro and basalts and iron-rich materials of the Northeast, all the way to the pipestone in the west.”

“The more local the stone is, the more welcoming it is,” says Salmela.

Until the business closed, Salmela sourced some of the stone for his projects from a former taconite mine in Hoyt Lakes, Minnesota, a site purchased by an enterprising entrepreneur selling Minnesota stones to builders, landscapers, and renovators all over the U.S. The enormous, acres-large mines had loose pieces of stone lying on the ground in all colors and patterns: banded taconite, Virginia slate, green diopside, yellow Mary Ellen jasper, and richly textured, black Animikian fossilized seabed that might be as ancient as a billion years old.

Judging from the fuzzy and now-microfilmed staff photo from the Tribune, the rock that the Brookdale killdeer chose to nest on was most likely Dresser trap rock, a dark igneous rock running the spectrum from gray to cool black and quarried just over the St. Croix River in northwestern Wisconsin. It’s something you might find along a roadway or on a railroad bed, and it’s been a consistent presence in landscaping designs for a century. Even those modest stretches of landscaping rock separating the sidewalk from the Brookdale parking lot was inviting enough of a space to allow a small visitor passing over to occupy it for a bit.