The last two days of the historical dig on Chestnut Street unearthed a discovery of great historical significance. “Everything really came into focus,” said Craig Chartier of the Plymouth Archeology Rediscovery Project. “We couldn’t have hoped for more.”

The two-week dig had been a success right from the start, as volunteers excavated dozens of artifacts from Pilgrim and Native American times. They also found a stone foundation, proving the spot was the location of Duxbury’s second meetinghouse. (The first was located where Standish Cemetery is now, the third is where the First Parish Church is on Tremont Street.)

But it was on the last day of digging that the team really stumbled upon something special.

Diggers discovered a series of post holes, 20 inches in diameter, along the north wall of the foundation. This means the building was originally constructed by means of “post-in-hole construction.” This was the way buildings were built at Plimoth Plantation, and it was thought that the technique hadn’t been used since.

“It is viewed as a quickie technique, a form of impermanent architecture which we all figured that the settlers would want to abandon in favor of solid cut granite or field stone foundations,” wrote Chartier in his blog.

He went on to say that Duxbury volunteers had worked on the only 18th century post-in-ground structure ever found in New England, and only one of a few in the country.

“It has the potential to change our view of architectural styles and techniques and the notion of what was conventional and standard in architecture in the 18th century,” Chartier wrote. “In theory, the original builders of the Second Meeting House should have been able to acquire the stones to make a solid foundation, but they didn’t. Why not? That is a new research question and one that we will be investigating over the winter.”

The discovered only adds to the value of what was already a successful dig. Duxbury Rural and Historical Society Director Patrick Browne told volunteers on Saturday at a wrap-up meeting that they had participated in a special part of Duxbury’s history.

“You folks have been absolutely wonderful,” Browne said. “Everybody took this seriously and worked hard. You didn’t let anything slip through the sifter.”

Volunteers at the site said they enjoyed participating in the dig.

Gene Blanchard found a musket ball while sifting dirt. He said he didn’t immediately recognize what the small metal ball was, but had a hunch he’d found something of significance and brought it to Chartier, who confirmed it was an ancient piece of ammunition.

“I’ve always been interested in archeology,” Blanchard said. “It’s always important to learn where we came from.”

Shelia Lynch, a member of First Parish Church’s historical committee, said she was drawn to the project because of the possibility of finding Native American artifacts. The second meetinghouse site overlaps with a Native American site called Morton’s Hole, where a 9,000-year-old spear point was found in the 1970s.

“Duxbury is not only a 400-year-old community, it’s a 9,000 year old community,” said Lynch. “What really drew me to this dig was the layers of history.”