UNITY – As visitors stood alongside slow-running Sandy Stream, the soft whistle of the wind through leafless trees was punctuated suddenly by the sound of geese flying overhead, fleeing Maine’s impending winter.

The wind blew Saturday morning and the sky threatened to snow, but for a group of Unity College archaeological students, this spot is much more than just scenic: It is historic.

A massive tannery and brickyard, the town’s largest employer, once stood here. It was likely the center of the community, said senior Christina Newberry, who on Saturday morning was taking visitors on tours of the tannery site.

Each fall, groups of 20 students in professor Chris Marshall’s “Culture and Environment: The Archeology of Sandy Stream” course arm themselves with shovels and spades and search the spot, not just for treasures, but for a greater sense of history.

“It’s like a puzzle,” junior Beth O’Neil said. “We are trying to put the pieces together.” After nearly two years of studying, the students admit they have more questions than answers.

The tannery was actually two buildings, each possibly three to four stories high, Newberry said. It was steam-powered and covered three-quarters of an acre.

The tannery was active in the mid-1800s and was burned to the ground when some patriotic and spirited residents were celebrating the end of the Civil War. But it likely was already approaching failure as its primary source to tan the leather was hemlock bark, and the tannery had cut down every tree for miles.

Over the past 150 years, nature has reclaimed the Sandy Stream banks, and huge trees have burst through the tannery’s old foundations. The students have been digging carefully and sifting the soil to find evidence of that long-ago way of life.

Spread out carefully on the rock foundation were some treasures: a broken blue bottle, nails, panes of colored window glass, a glass file.

Student Kyle Koch admitted he was the “bottle man,” intrigued by glassware found in the ruins. “This just fascinates me,” he said.

“When I first came to Unity [College], I had walked right by here and didn’t know this existed,” Newberry said. “It makes you wonder what else is hidden, overgrown through the decades.”

She said the discovery this fall of a massive brick pit and bricks used to create a kiln to cure the bricks was surprising.

“We have no idea what they did with the bricks,” Newberry said. Row upon row of hand-struck bricks are being excavated from the side of the stream.

As the weather turns cold, the students will move inside the classroom and begin investigating and cataloging all the artifacts they have uncovered. They are putting the information into a book, which they hope will be completed by next fall.