Rockefeller wall behind Coach Barn, Pocantico Center, Tarrytown, NY. Photo by John Phillips, April 2016
Amazing. One minute and I was inside the lovely conference center in the Coach Barn on the Rockefeller Estate in Tarrytown, Westchester County NY. The next minute I was out the back door standing below a wall at least 30 feet high and built of massive boulders plucked from nearby fields. With me was a group of architects, educators, artists, and staff of the Pocantico Center, which arranges tours of grounds of this property, now managed by the National Trust for Historic Preservation. The questions kept on coming. Why so tall? Where are the boulders from? Why do they let the ferns grow through them? And above all – How come it doesn’t fall down?
I made up the answers on the the fly just by looking at what I could see. To the right was a “battered” wall of dimension stone, which means it was cut straight from the quarry to the proper dimensions. And yes, the word battered is correct, for that’s the word for the angle away from vertical that the wall is laid for ideal support. To the left was a massive arch, also built of dimension stone, through which the horses and carriages used to enter what had been the finest barn I’ve ever seen: an enormous structure built of quarried gneiss. Between these two masses of quarried stone was inserted the wall you see. Some of the boulders were a yard in diameter with nary a scratch mark on them. Indeed they were “milled” within the shear zone at the bottom of the ice sheet that spread them over the land before melting down to a last gasp. The placement was the ideal mix of random and deliberate, with no real “courses,” as with a brick wall, and no more than one “tier” meaning only one group of stones from bottom to top, at least in this view.
It’s such fun so share something so fun. With just a few words for stone size, shape, composition, and surface texture, the tour group began to sound like experts. They were now empowered to go “Exploring Stone Walls,” the title of one of my books.
Block Island Wall: Is this a landform? That depends
To answer the question of whether stone walls are landforms, I like to start with the word “landscape.” According to Webster’s this 16th century word derives from the Dutch landschap, meaning “land + ship.” Tracking back through the etymology of the Oxford English Dictionary, however, indicates that the concept clearly predates the 5th century A.D.
Being empirical, ignoring the conventions of art history, and based on the way I hear the term used colloquially and professionally, a landscape is not a place, but an image (visual or mental) of a place that consists of physical entities and that can be seen and appreciated by the human eye from a single spot, often by a single glance. Technically, its the cone of human vision at the familar scale of village, coast, or rural geography. A human presence is always either present or suggested.
In contrast, a landform is easy to define because no cultural connotation is required. Nor is there a required scale. To geologists like me, a landform is any natural discrete physical object composed of “land” (rock or earth) that can be observed in its entirety. Because humans were visual primates long before they became stone-age men and women, the form of the landscape (landform) has held higher priority over the equally important elements of the material they consist of, the process creating them, and the time involved.
Typically, a landscape is younger and larger than the set of landforms within the scene. The only exception to this commonality is when the natural scene contains little or no topographic or lithologic variety, for example a sand plain as smooth as a glassy sea such as the the Llano Estacado of west Texas.
So are New England stone walls landforms? It think yes, even though I included the term “natural” in my definition. First, the vast majority of walls are no more complex than many natural forms, a star-dune for example, or the herringbone structure on a fine-sand beach. To exclude them as landforms because they were built by humans is to suggest that humans are not natural. I refuse to accept this false, and damaging dichotomy.
Tarnished wood and stone on an ancient building at the Eric Sloane Museum in Kent, Connecticut.
In political dialogue, the infinitive “to stonewall” means to delay or prevent something by putting up a serious barrier of some sort. Not so for those of us who appreciate the fine art of building a stone wall from scratch, given a supply of stones. Fortunately, there are a growing number of workshops that individuals can sign up for to learn the art, or practice, of dry stone masonry.
For most people, this is a ritual way of entering New England’s former stone age, generally spanning the 18th and 19th centuries. For me, it’s like playing outdoor chess. Indeed, some pieces are more valuable than others, strategy is important, and pawns are often sacrificed en route to victory. And all of this takes place aerobically outdoors.
Last week I was at the Eric Sloane Museum in Kent, Connecticut to spend a day in celebration of New England’s historic stone walls. This event overlapped with one such stone wall workshop, hosted by the “friends” group of the museum taught by Carl Dill. The previous week, I recall reading about one at Parmelee Farm in Killingworth, taught by Andrew Pighills and Dan Snow. And this week I learned of one being offered in Portsmouth, New Hampshire, sponsored by the Wentworth Gardner and Tobias Lear Historic Houses. With news of three such events reaching the Stone Wall Initiative in as many weeks, I decided to write a blog posting alerting readers about the phenomenon in general, and Portsmouth’s 2 day intensive hands-on masonry conservation class in particular. It will run on June 13 & 14. The contact person is Sandie Dika, who can be reached at 603-426-9282.
Sampson Rock in Madison, CT is a special and evocative place This is a glacial erratic, a “rocking stone” and, in this taxonomy, a Notable Stone.
Of course there are! There have to be! Hundreds of thousands of human beings have walked and worked the New England uplands for at least 11,000 years. And many features have been confirmed as pre-Colonial by properly credentialed archaeologists.
But let us not conflate the few, the small, and the odd stone features in the woods with the latticework of abandoned stone walls gracing much of the New England countryside. This latticework of walls is the collective work of colonial and early American farmsteads built by Euro-settlers and their descendants since 1607.
Last night, while giving a talk to the Boxborough Conservation Trust in Massachusetts, I got the inevitable question about pre-colonial stone ruins. This morning, I decided to post my answer in the form of a keynote speech I gave several years ago to the New England Antiquities Research Association.
Friday, February 20, 2015 was a bitterly cold night in New England. At the University of Connecticut where the SWI is based, the overnight low was -15 F. The following morning, stone wall enthusiast Kate Johnson sent me a video-clip taken by her parents, Claire and Steve Johnson, from Little Compton, RI. It showed steam rising from a stone pile like smoke from a dying campfire. Thinking other stone wall enthusiasts might be interested, I decided to post it on the SWI website. Click on this link to see it.
To understand this, let’s start with the simpler case of steam rising from a patch of open water on a frozen pond or a stream. Under calm, but not cold atmospheric conditions, the extra moisture above the liquid water is invisible because it’s water vapor, a clear gas. But when the ambient temperature becomes very cold, the air above the patch is much less dense and moist than elsewhere. So it rises, cools, and condenses into a fine mist. These tiny droplets then migrate away, evaporate in the cold dry air, and become invisible once again. Something similar happens above chimneys, drier vents, and volcanoes.
Now imagine a deep fluffy snow on a forested New England soil. The insulation of the snow adds to the insulation of the forest mulch, to prevent or restrict the depth of frozen ground. In this situation, the air within the unfrozen soil –driven by gradients of temperature and vapor pressure–migrates upward to the base of the snowback, condenses, and is frozen before it can be seen.
When the snowpack is crusted with ice, however, this upward escape of soil air is blocked. And when frozen ground is deepening, or when the water table is rising, the soil air is squeezed sideways toward a place of escape. Old stone piles and tumbled stone walls provide these avenues, becoming vents for warm moist air. The extra cold of the stones (caused by more rapid conduction of heat) may help speed up this process.
As with a patch of open water on a frozen pond, the patch of warmer-moister air beneath a stone pile rises, cools, condenses, and evaporates, producing a ghostly transient mist. The careful observer of nature gets chance to see native fieldstone steaming away.
Thanks Claire and Steve for catching this process in the act. Spread the word. Share the stone joy.
We are delighted to announce that Stone Wall Secrets (1998) has been republished under the same title in a new edition (2014) as a Tilbury House Nature Book as part of its Learning Center. Authored by Kristine and Robert Thorson (illustrated by Gustav Moore), this book was reprinted in hardcover and paperback before being re-issued in 2014.
As part of this process, and beginning in March, 2015, Professor Thorson will be heading back into elementary school classrooms to conduct hands-on programs, during which signed copies of the book will be made available to all students at the cost of printing and shipping.
Pink granite vein in darker boulder lifted up into a stone wall on Block Island.
Walking down a trail somewhere on Block Island, I caught sight of a light-colored dike (vein) that seems to be sharply bent. This doesn’t make sense because there are no other fractures and no other indications of folding. What you’re looking at is optical illusion created by a pair of planar facets on the surface, each of which is one side of an old fracture. These facets change your angle of view in such a way that they make the dike appear to be bent. Proof that this is so is the next photo, taken parallel to the plane of the dike. From this direction, the angle the facets don’t change the appearance.
Same pink vein now appears planar.
This mini-mystery was only one of many delightful things I saw during a trip to Block Island in mid July to run a field trip, give a lecture to the community (sponsored by the Block Island Gardeners), and enjoy the cool fog. Everyone who was on the trip with me looked at this optical illusion, and found it interesting. Another was the standard or “archetype” block island wall, taken in the southwestern corner of the island, where the land is preserved from future development.
Typical Block Island stone wall.
Note the uniformity of pink granite, the general blockiness of the stone shape, and the subequal mix of semi-rounded and angular fragments. This indicates “bumper-car” style of boulder traffic in the basal shear zone of the ice sheet, which rounds stones until they break, only to be rounded again.
That’s me, standing in front of about seventy third graders in Guilford, CT at the Calvin Leete Elementary School on Friday the 13th of April. In the air are the wiggly hands of nearly seventy third grade students. Why?
The answer to my question was a display of hands up in the air. What do you think the question was?
Because I asked them: “How many of you have a stone wall in your backyard or in a nearby place?” The hands shot up. The enthusiasm was palpable. Every student, it seemed, wanted to tell me about their own favorite wall.
The four classroom teachers and their staff were quite proud of their student’s excitement about the subject, which had just been introduced as part of their earth-science curriculum. They will be linking this subject to other subjects required by the curriculum, namely language arts, science, history, art, and mathematics. I was there to read and discuss the award-winning illustrated children’s book, Stone Wall Secrets, for which we wrote a curriculum several years ago.
Block of siltstone in wall in Hartford CT containing mud cracks from an ancient shoreline in which dinosaur footprints and bones have been found.
During my many years of visiting classrooms, I’ve found that elementary school kids like these are no less interested in stone walls than in dinosaurs, volcanoes, and glaciers. All it takes is a teacher willing to embrace stone walls –New England’s signature landform– as a launching pad for their earth science teaching, rather than the more national generic menu offered by the national publishers. Did you know that dinosaur footprints, lava flows, and glacier-marks have all been found on the stones within the region’s walls? Indeed, these three phenomena are but chapters in the grander story of New England’s stone walls.
Two days later, I was standing in front of an altogether different group. All were over thirty and most were senior citizens. This was the Middletown (RI) Historical Society, located in a town that occupies the bulk of Aquidneck Island in Narragansett Bay, and is responsible for its best beaches. To the south and north are the more well known towns of Newport and Portsmouth, respectively.
This rural residential town is one of three in the state having an ordinance for the protection of stone walls. Congratulations for their foresight. This much-older group was equal to the third-grade children of Guildford in terms of their enthusiasm, and they were the ones asking the questions. In fact, there were so many questions early on that my talk went overtime, forcing the reporter and photographer sent by the Newport Daily News to leave early.
The most iconic item in the historical society’s collection is a spectacular windmill reconstructed in Paradise Park, adjacent to the society’s small museum, a one-room schoolhouse on the National Register of Historic Places. When rigged with all eight sails, Boyd’s windmill, built in 1810, provided the power to rotate one grinding stone above another to convert historic Rhode Island’s grain into flour.
Basal millstone of Boyd’s Gristmill (1810), which was originally located in Portsmouth and moved to Paradise Park in Middletown, RI.
Its pair of cylindrical grinding stones –one intact, and one broken– provide a perfect example of what I call a “Notable Stone” in my taxonomy. Though both were made of durable granite, the top one broke with what engineers call “stress fatigue,” the accumulated result of too many vibrations for too many years.
Though the grinding stones were fascinating, I thought that the local stone walls were even cooler than the millstones. Though built recently, they capture not only the local style of the well-built historic walls, but also the relative abundance of the local stone in their proper proportions. The vast majority of rock on Aquidneck Island the gray to green-gray muddy sandstone and sandy mudstones known to geologists as the Narragansett Formation. The locals call it slate. In the photo below is a boulder of pudding stone (right) and a block of quartz from a vein. Both are common, but less abundant variations within the local rock.
Recent wall in Paradise Park, Middletown, RI. .
These two recent SWI programs illustrate the range of interest in the phenomenon throughout New England. If you’re interested, contact me (Robert M. Thorson), the coordinator through this website.
Boulder of red sandstone blotched by lichens, and stacked into a roadside wall in Somer’s, CT. This rock is rare in New England walls because it was so easily crushed during glacial transport. And when quarried, it quickly disintegrates.
The Stone Wall Initiative (SWI) is coming back to life with more vigor than ever before. After its launch in 2002, its coordinator, Robert M. Thorson, spent about six years as a stump evangelist speaking on behalf of stone wall conservation, publishing essays, and being a traveling educator to school classrooms, state parks, and non-profit environmental organizations.
Things went quiet between 2008 and 2013 when I diverted more of my energy to a separate “signature landform” project on the galaxy of small glacial lakes decorating the northern fringe of the United States, leading to the book Beyond Walden: The Hidden History of America’s Kettle Lakes and Ponds (Walker, 2009). This led to a scholarly investigation of Walden Pond, which led to the book Walden’s Shore: Henry David Thoreau and Nineteenth-Century Science (Harvard, 2014).
Though the SWI went to the back burner during those years, the requests for talks and workshops, and queries from stone wall enthusiasts continued at a moderate clip. Now, after a five year period of quasi-hibernation, the SWI is bouncing back as an important component of my scholarly engagement at the university. To serve the education goal, I’ve resumed classroom visits using Stone Wall Secrets. For conservation, I’ve become involved in involved legislation. For investigation, my colleagues Will Ouimet and Katherine Johnson have published a spectacular geo-archaeology paper on New England’s hidden landscape. And for appreciation I’m trying to load this website up with information whenever I get the chance. When that’s done, I’ll start putting together some one-minute videos to answer common questions.
Please give the “new and expanded” site a quick overview, and check back every once in a while, as we will be building it steadily for the next several months. It feels good to be back.
