Written in Stone

A forest grown up around a stone wall in Grafton, Vermont.

Stone walls are a defining feature of the northeastern landscape, snaking through the woods and fields, across ridges and valleys. They are monuments to life and to lives gone by. We caught up with Robert M. Thorson, a University of Connecticut geology professor and an expert on New England stone walls, to talk about what he calls the region’s “signature landform.”

Thorson didn’t grow up with stone walls. He moved to New England from Alaska to work as a landscape geologist and was getting the lay of the land, so to speak, in Natchaug State Forest in eastern Connecticut when he came across his first stone wall. “I was mystified,” he recalled. “Just arrested in my tracks. ‘What is that thing? Why is it here?’ It seemed out of place because I was in a closed-canopy forest. That’s what got me started on it.”

Since then, Thorson’s founded the Stone Wall Initiative, which features an online informational portal designed to inform the public, and written three books about New England’s stone walls. He’s also a Thoreau scholar. His latest book, just out, is The Guide to Walden Pond, from Houghton Mifflin Harcourt.

What explains the differences in stone walls in various parts of the region?

There are three basic factors, Thorson said.

1. Construction style: There's a four-step gradation here. The most primitive stone walls, basically thrown piles, mark what Thorson calls the “pioneering” phase of construction. At the other end of the spectrum are elaborate “mason-contracted walls around rural McMansions.”

2. The type of rock: “If you have layered metamorphic rocks, you’re going to get nice, slabby stone that ends up as tablets and slabs,” Thorson said. “If you get granite, you’re going to get blocks and balls.”

3. Glacial handling: Rocks that were on the bottom of the ice sheet are going to be more worn than rocks that were on the top.

Written in Stone Image

This remnant of single wall construction in Lyme, New Hampshire, shows a variety of features: Shapes are blocks, slabs, and pillows; sizes are mainly two-handers, with one one-hander; order is stacked, rather than laid or tossed; structure is a single-tiered, un-coursed wall one-on-two-and-two-on-one, with one error; lithology is mainly granite and gneiss. Photo by Robert M. Thorson.

Were New England’s stone walls really meant to pen animals?

A tiny fraction, maybe. Most, no. Stone walls were often made in conjunction with wooden fences for livestock; farmers chucked stone under the fence rails to get it out of the way. “It’s a linear landfill,” said Thorson. Later, the wooden fence rotted away. Some farmers did tidy up their stone walls. And during the Gilded Age, said Thorson, wealthy industrialists bought rural farmsteads and rehabbed them, hiring people to turn the thrown stone walls into architectural features. Thorson noted that in New England, fences were regulated by towns and generally were required to be four feet, six inches to five feet, six inches tall to keep cows out of the neighbors’ corn. “There are very few stone walls in the woods that are that high. They’re basically knee-high to thigh-high. That means they were not fences or walls in and of themselves.”

What was the heyday of stone walling in the Northeast?

New England was settled over centuries, with the population spreading from the coast westward and northward. Thorson places the peak of stone wall “construction” between the beginning of the American Revolution – say, 1775 – and the completion of the Erie Canal in 1825. “Now that’s only 50 years, one-eighth of the history of New England, and I’m just guessing that about half the walls went in in that span of time,” Thorson said. He notes that many revolutionary soldiers were rewarded with frontier land for their service. As those lands were settled, farms grew and the new country underwent something of a baby boom.

It took tons – pun intended – of work to construct these walls. How did our forebears do it?

Written in Stone Image

This tall single wall in Marion, Massachusetts, is high enough to qualify as a standalone fence. A single-tiered, un-coursed wall is dominated by angular, half-rounded, and rounded blocks and balls of pink granite, with a few slabs thrown in for stability. The “look” of the wall is a function of the mixed glacial “handling” of ancient, massive Proterozoic granite. Photo by Robert M. Thorson.

Basically, big families and teenage boys, said Thorson. All that youth and vigor was put to work picking stones if they didn’t have another job to do. “They’d go build stone walls because they had that youthful testosterone and aggression,” Thorson said. As he noted in Stone by Stone, “The average farmer probably spent twenty-two times as much effort to heat his home as to clear his fields of stone.” Much of the work was done in the “off season,” when sowing and hoeing and harvesting weren’t on the agenda. Late fall and early winter were prime time for wall construction – before the snow came and the ground froze, Thorson said. Typically, smaller stones were tossed into the fence line if they were the right size and within 20 feet of the edge of the field. In the interior of the field, people rolled stones onto a sledge called a stone boat, and then pulled them with oxen to the fence line and rolled them off.

The New England–New York region is famous for its stone walls, but other places have them too, right?

Yes, the carefully crafted dry stone walls of Ireland and the United Kingdom are famous. There are also stone walls in the US Virgin Islands, in Michigan, in Hawaii, in the Pueblo ruins of the desert southwest. Even, Thorson notes, in the Sierra Nevada. That shows, said Thorson, that “it’s not a cultural tradition, but something more organic – there’s a job to be done and human beings are just doing it in the same way.”

How many miles of stone walls are there?

Written in Stone Image

Robert Thorson’s teaching wall in Storrs, Connecticut. This is the archetype wall for the crystalline metamorphic terrain of southern New England: a classic farmstead wall consisting of a single, un-coursed tier of stacked two-handers. Photo by Robert M. Thorson.

One of the first estimates for the length of the stone walls in New England came from a mining engineer who wanted to use them as quarries. He guessed around 240,000 miles, said Thorson, or about the distance to the moon. But in the decades since, many stone walls have been repurposed, providing crushed stone for roads, material for wharves and piers, and fill for low or swampy areas. At one time, the federal government was advising farmers to use them to drain farmland by digging a trench next to a wall and pushing the stone wall into it.

How do stone walls affect the environment?

Stone walls make our landscape more alive, Thorson said. They create shade and a moist environment on one side, and they warm up the soil and rocks on the other side. “They’re heat pumps and ventilators,” said Thorson. “They introduce a vertical billboard to the landscape and that increases habitat diversity. You get wet and dry, shady, moist, windward and leeward.” Creatures of all types use stone walls as housing and shelter, lookout platforms, and travel corridors. Foxes, chipmunks, minks, salamanders, mice, voles, bobcats, and even bears use them.

What is there about those falling-down stone walls that speaks to people?

Well, Thorson posited, it’s that stone is elemental – almost literally a touchstone. It seems to have a permanence that we ourselves do not. That’s one reason that stone is used for gravestones, he notes. “There’s a reverence for stone. We all feel it.”


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