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.
