The abandoned fieldstone walls of New England are every bit as iconic to the region as lobster pots, town greens, sap buckets and fall foliage. They seem to be everywhere – a latticework of dry, lichen-crusted stone ridges separating a patchwork of otherwise moist soils.

Stone walls can be found here and there in other states, but only in New England are they nearly ubiquitous. That’s due to a regionally unique combination of hard crystalline bedrock, glacial soils and farms with patchworks of small land parcels.

Nearly all were built by European settlers and their draft animals, who scuttled glacial stones from agricultural fields and pastures outward to fencelines and boundaries, then tossed or stacked them as lines. Though the oldest walls date to 1607, most were built in the agrarian century between the American Revolution and the cultural shift toward cities and industry after the Civil War.

The mass of stone that farmers moved in that century staggers the mind – an estimated 240,000 miles (400,000 kilometers) of barricades, most stacked thigh-high and similarly wide. That’s long enough to wrap our planet 10 times at the equator, or to reach the Moon on its closest approach to Earth.

Natural scientists have been working to quantify this phenomenon, which is larger in volume than the Great Wall of China, Hadrian’s Wall in Britain and the Egyptian pyramids at Giza combined. This work began in 1870 and generated the U.S. government’s 1872 Census of Fences. Today, scientists are using a technique called LiDAR, or light detection and ranging, to measure and map stone walls across New England.

Being a geologist, I’m interested in walls as landforms that are distinctive to the region, created during the lead-up to the Anthropocene epoch – a time when human agency dominates all others. I’ve written about the history of stone walls and how to interpret them in the field, and developed the Stone Wall Initiative to draw public attention to their importance in New England. Now, I’m working with students and colleagues to develop a formal interdisciplinary science of stone walls that will help researchers understand and preserve them.

My brother-in-law enjoys his backyard wall in Lee, New Hampshire, mainly for its aesthetic, historic and literary ambiance. The wild things living in his neighborhood depend on it as unique habitat.

To lichens and moss, the wall’s dry stones are surfaces where plants can’t compete. For plants, such walls are edges that separate patches of ground into zones that are sunny or shady, windward or leeward, uphill or downhill, wetter or drier. Stone walls offer small mammals porous volumes in which to live their furtive lives. Predators use the walls as hunting blinds and travel corridors.

Just for fun, my brother-in-law installed a motion-activated, infrared video camera on his backyard wall to see who was using the wall and how. On June 21, 2023, the summer solstice, he filmed a bobcat (Lynx rufus) hiding behind it and then using it as an elevated pathway.

The more we researchers learn about New England’s abandoned stone walls, the more we realize that they transcend and obliterate the narrow treatments of our scholarly disciplines. These archaeological artifacts are so ubiquitous that they have become a geological landform that in turn creates a novel ecological habitat. These walls also are literary icons, historic sites and spiritual oracles, as Robert Frost recognized when he penned “Mending Wall,” on an old farm in Derry, New Hampshire.

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