How a possible 18th century tide mill site was recently discovered in Connecticut
“Gold is where you find it” was how prospectors responded when asked where to seek the precious metal during California’s 1849 Gold Rush. They were saying gold could be anywhere – but you had to look for it. The same could apply to finding old tide mill sites, and that’s the core message in a tide mill hunting lesson by Mark Borton, a seasoned discoverer of tide mills, independent historian, and author. Mark often travels from his home in Connecticut to Maine, Nova Scotia, and other places to investigate possible tide mill sites, but his latest find is a shorter drive: Old Saybrook, Conn.
It all started with general windmill research for another project, which revealed the existence of a 1636 windmill in Old Saybrook. He couldn’t resist going there to see a millstone from that windmill and visit the town’s historical society to search for more information about it. There he discovered that Old Saybrook has 10 historic mill sites, including two tide mills. One was at the Ox Pasture dam and the other at Oyster River bridge.
Living in the area but having never heard of Ox Pasture, Mark just had to find its location. He saw the Oyster River mill on an 1811 map, but neither Ox Pasture nor the Ox Pasture mill was mentioned on this map or on a 1791 version. Fortunately, a map drawn in 1878 for recording features existing between 1636 and 1830 identified Ox Pasture – but it still did not show a mill.
While this could have been a dead end, there was more to be learned in the historical society’s archives. Notes by a 1990s researcher mention a resident’s second-hand knowledge of a mill foundation “in the marsh off Trask Street.” That researcher had dismissed the idea at the time because he believed it wasn’t possible to construct a mill in a marsh. But Mark knew from his years of tide mill research that mills were often built in marshes, so it was possible that someone’s recollection of a mill foundation was accurate after all. What’s more, a Google satellite view showed some unnaturally straight river channels near the end of Trask Street, indicating some human efforts to redirect river flow. Aerial photos from the 1930s showed even more evidence of man-made alterations to the river channel.
Mark thought this looked like a very good place to search for physical evidence of a tide mill. So he did, and there it was: an obvious sluiceway constructed with vertical planks, timbers, and stone rubble filling in spaces between wooden water channeling structures.
Documenting the Find
Mark knows the importance of properly recording and reporting site details so they wouldn’t be lost again. To help get this done, he was able to enlist the aid of an about-to-retire surveyor, Nancy Bryne. And Nancy wasn’t afraid to put on boots and explore the muddy location both in person and with her drone.
This survey was more than just surface features. Mark and Nancy drove coring pipes into the mud for extracting soil samples down to a 4-foot depth. These cores revealed that 2 feet below the roots and mud of the marsh was sand, indicating the area had been filled with sand – more evidence of human construction activity.
They also recorded a cross-section of the water channel at the location of the mill ruins, helping confirm that items now deep in the mud would have probably been at the surface in the late 1700s. Since that time, sea level has risen and deposited mud and vegetation to create what is today’s top level.
A Tentative Conclusion
The remnants of the structure looks like they were meant to control water flow, and they’re at the right depth to do that in the 1700s. This led Mark to think he might have found the Shipman tide mill from 1774. But could it be something else? That’s possible, Mark admits, but more and more evidence is supporting the presence of the 1774 mill.
The detailed hydrographic survey by Mark and Nancy, with 1-foot contour lines on the land and river bottom, shows another man-made structure on the main river channel a short distance southeast of the suspected tide mill ruins. This feature may have been a wharf, as it has straight sides and walls appearing to rise vertically from the river bed.
They also mapped an array of stone, shell, and wood materials located about 2 feet below the surface. These were detected by pushing a 1-meter rod or soil probe into the river channel bank. Mark was able to use the sound of the probe contacting the buried objects to differentiate among the three material types with some accuracy. Each detection was marked by a target or flag, photographed by the drone, and then marked on a map.
Historian to Archeologist
One of the visible items partially buried in the mud at the site was an old timber with obvious mortises that would have been used to join mill components together. It would make sense, Mark thought, to inspect this item closely, analyze its details, and determine its age. It could be another piece of evidence to confirm it as part of the 1774 mill. “Now we’re really getting into archeology,” he said.
Deliberately unearthing historical artifacts and doing archaeological excavations requires a variety of permissions and permits in Connecticut and most states. Accordingly, Mark recruited Nick Bellantoni, Connecticut Emeritus State Archeologist, who agreed to supervise an excavation staffed by Mark and volunteers. On excavation day, a brilliant 70 degrees (F) in April, all the timbers were measured and the old hand-hewn timber with the mortices was lifted from the mud for closer examination.
The old waterlogged piece of wood offers convincing evidence of its age. Mortices made without drill holes, chisel and adze marks, an axe-cut end, and the absence of saw marks all seem to show that the timber features were created before 1800. A small piece of the timber has been sent for radio-carbon dating, and the result will determine whether the historical society will preserve the timber. (A member of the local historical society volunteered to pay for preserving the timber, if dating indicates it should be preserved.) The timber may also be analyzed via dendrochronology (dating tree rings to the year they were formed). The combination of carbon dating and dendrochronology could identify the age within a 30-year window or less.
Questions Remain
The result of the research and documentation to date has raised additional questions that could be answered by additional research:
- It’s possible that a dam was built in this location at an earlier time, and Shipman’s 1774 mill was built on the site of an earlier dam. An 1884 document states the mill was built “at the Ox Pasture dam,” and this could mean the dam already existed when the 1774 mill was constructed. That dam could be associated with another mill in that area that was under construction in 1649, or another 1691 mill. This is why dating the timber is so important to resolving that question.
- A slight raised area along the edge of the channel could be remains of a much longer dam, which would create a large mill pond. Mark speculates that this larger dam could have been destroyed in the 1600s, and a smaller dam for Shipman’s mill was built in 1774.
- A description of the mill describes it as “new and peculiar construction.” Could this mean the mill was bi-directional, or operating on both the rising and falling tide? This configuration was rare during the likely period of this mill. Since, as Mark explained, most of the bi-directional mills of the time were unsuccessful, the mill may have failed and thus disappeared from the historical record.
- Should further surveys be conducted using ground penetrating radar, excavation, or other methods to determine what was built, when it was built, and by whom?
For much more detail about Mark Borton’s discovery and investigation of the Ox Pasture tide mill in his own words, watch his presentation at the 2026 Tide Mill Conference in Fairfield, Conn., here.
Mark continues the Ox Pasture investigation in parallel with an ambitious research project he directs in Nova Scotia. See more on that project here.