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Date: 10/19/2022
SOUTHWICK — Professor William Ouimet spent a recent Friday afternoon nearly knee-deep water in the Sofinowski Preserve off Mort Vining Road, driving long metal tubes into the earth below the surface.
Aided by his graduate students from the University of Connecticut (UConn), Ouimet had been drawn to Southwick by a series of distinct land depressions within the town-owned conservation area. To the layman, the sunken earth would probably not stand out among the hilly, forested terrain of the Sofinowski Preserve, but to Ouimet and his earth science students, the depressions could be evidence of ice age activity in the area, known as glacial moraines.
“It happens that Sofinowski Preserve has these interesting landforms, these circular rimmed depressions,” said Ouimet to Southwick’s Conservation Commission on Oct. 10. “These landforms are common across the entire region and have a specific history related to glaciers.”
Ouimet had identified several such formations in the Sofinowski Preserve using a technology called “LiDAR,” or light detection and ranging. Using a LiDAR map, Ouimet is able to see details in geography that one would likely miss even with a bird’s eye view.
When Ouimet and his team arrived in Southwick on Oct. 13, they loaded their coring tubes, a generator and other equipment onto a cart and rolled in along the uneven trail until they got to their destination, which itself was off the yellow trail of the preserve. Of the several depressions they identified, only one ended up being a viable candidate for core extraction, due to how rocky and hard the ground is at the others. The several-meters-wide depression happened to also be filled with water in a near perfect circle due to recent heavy rains, leaving only a small “island” in the middle for Ouimet’s team to work off of.
Wearing high boots to keep their legs dry, Ouimet and his students had to work as a team to drive the coring tube into the ground. The generator they brought with them was meant to power a device that vibrates the tube into the ground while someone stands on it, like a pogo stick, to drive it through the mud and dirt, about 15 feet below the surface.
More difficult than putting the tube into the ground was pulling it back out. Ouimet warned that it is very common for a core sample to be lost on an extraction attempt, simply by the dirt and sediment falling out of the bottom if one is not careful. Thankfully for the UConn team, the cores were successfully capped and brought out of the Sofinowski Preserve, after which they were brought back to Connecticut for further study.
What was immediately apparent to Ouimet and the students was that the bottom-most layer of their sample was a malleable clay, easily taken into their hands and molded into different shapes. They joked that it was the first time these bits of sediment had ever been observed by a human.
Ouimet said the presence of clay may point to the area having been a “still water” environment when fine sediments like clay would typically accumulate. It may not have necessarily been a wetland, but possibly a pond about 1-3 meters deep, he said.
The class will study the core samples over the next couple of months, and give a report to Ouimet in December about what they have found. The core was opened up for the first time since its extraction on Oct. 14, after which the cores were cleaned and analyzed for things like color and grain size.
Then they will have to determine where in the core there is an accumulation of carbon, and use that material to carbon date the core and more accurately determine the age.
Based on the evidence they had as they extracted the cores, Ouimet said the sediment could be between 15,000 and 18,000 years old.
Another possibility, which is being explored at similar sites in Connecticut, is that these formations are “pingos,” which form only in permafrost environments when underground pockets of water freeze and then thaw, causing a “collapse” of the dirt above it into a concave formation, similar to what they found in the Sofinowski Preserve.
Ouimet offered to return to Southwick sometime early next year with their findings to give a presentation to the Conservation Commission.