The St. George River has everything Harbour Mitchell could want, but he’s not looking for a big catch, a quick current or a cool dip.

“You name it, it’s got it, from about 10, 11,000 years to yesterday,” he said of the river during an interview last winter at his dining room table, littered with dirty bits of ceramic and glass. “It’s got everything you could ever want in one package, you know, and it’s not a huge package.”

As an archaeologist who worked for the state in the ‘80s and ‘90s, Mitchell helped review potential sites of interest before they were torn up by construction projects such as gas lines, bridges and dams.

Now living in Searsport and earning his keep as a United Methodist pastor, he has continued his archaeological work. Most recently, he has investigated the area surrounding the Conway House, an 18th-century home in Rockport.

He has big plans to turn his focus to the St. George River. With another archaeologist, Paul Bock, of Stoney Knoll Archaeological Supplies in Stockton Springs, Mitchell aims to develop an entire research agenda focusing on the river and surroundings. He has high hopes for what he said is largely unexamined ground.

He is starting in Thomaston, near where the river meets Thomaston harbor, in an unremarkable-looking field adjacent to the current Thomaston Historical Society building and boatbuilder Lyman-Morse. There, he is digging a series of shovel test pits – 10-centimeter-square holes dug at five- to 10-meter intervals – to get an idea of whether the site holds anything of value.

Some of the field’s history is known. Much of it is not.

It was the original site of Montpelier, Revolutionary War Gen. Henry Knox’s 1794 mansion, which was demolished in 1871 to make way for a railroad, and which has been rebuilt in replica about a mile away, closer to Route 1.

The last standing remnant of Knox’s estate – a brick building tucked off of Knox Street – is now home to the Thomaston Historical Society, which, along with the town, has worked with Mitchell to prepare for the dig.

Before Montpelier, no one is certain about what, exactly, occupied this land, if anything. Over the years, many have suggested it was the site or near the site of Fort St. Georges, an 18th-century English fortification built to protect a toehold in French- and Native American-dominated eastern Maine. The fort shows up on contemporary maps, seemingly connected by an early coastal road to another fort in present-day Stockton Springs.

The fort is distinct from Fort Georges, a small earthen rampart on the St. George side of the river that saw action during the War of 1812, and which still exists at Fort Point.

An earlier effort by a University of Maine team to find Fort St. Georges in the early 2000s, on a site closer to the water, failed to turn up the hoped-for evidence. Both Mitchell and historian Margaret McCrea said excavating the waterfront would likely be futile, given long-term shipbuilding activity and the possible use of fill to extend the shoreline.

According to Mitchell, most of what is known about the fort is from second- or third-hand sources. What became Fort St. Georges started as a trading post in the early 18th century, when the English were already drawn by the area’s abundant lime, timber and fish, with fortifications added through the 1700s. As the nearby settlement grew through the 1750s, a proper fort was built. A sketch by McCrea shows a rectangular, 100-by-100-foot wooden structure with 16-foot-high walls and an enclosed walkway leading down to the water’s edge.

The fort was put to use. “The English came in, and it was just a culture clash,” said Mitchell, describing an era of frequent Native American attacks, followed by violent pursuits. The French also attacked at least once. “This was a very militaristic, very dangerous period of time.”

The French eventually yielded much of Maine, retreating Down East. And about 20 years later, the colonies were fighting for their independence from Britain.

McCrea has a map from 1762 that shows “St. George’s F” at the mouth of the river. A map dated 14 years later has it marked down as “now in ruins.” It is not clear why or precisely when the fort fell into disrepair, but with the growth of Thomaston and the decline of the French and Native American presence, it may simply have become obsolete.

According to Mitchell, it is likely General Knox built his estate more or less on top of or behind the old Fort St. Georges.

Then, since the time of the railroad construction and the demolition of Montpelier, the field has been almost completely unoccupied. “It’s never been developed – ever,” said Mitchell. “It’s extraordinary, in just that alone. So, from the 17th century on, with the exception of the fort and Knox’s mansion, things like that, there’s never been anything there.” That leaves open the possibility for undisturbed artifacts left by a variety of potential inhabitants.

“This field has the potential, then, to have any number of outbuildings, associated pieces to the fort or to the mansion,” Mitchell said. “There were blockhouses there originally, before the fort, so, 1720s, 1730s. It doesn’t get much older than that in Maine. And if you could find those, that would really be a coup. It’d be wonderful.”

Using LIDAR – technology that uses light to examine, and often map, the earth’s surface – Mitchell and Bock detected what appear to be a neat series of rectangles lined up in the field. One, Mitchell said, resembles a basement divided into four sections. He has hopes these could be the remnants of whatever structures might have been there.

Failing that, he has a more modest goal – sorting through old trash. He is hoping he can find bits of 18th-century litter – bones, kitchenware, tools — from the fort’s inhabitants, its besiegers or from Knox’s time.

“That’s the kind of material that you would want to have,” said Mitchell. “Because then you look at that and you say, ‘OK, what are they doing? How are they living? How badly are they living, how well are they living?’”

With any such findings, Mitchell and the Historical Society hope a timeline can be built of who or what occupied the land.

Adding to the possibilities are historical accounts that Knox had hired a number of African laborers to work on the estate, who lived on or near the property, and also that local Native Americans used to visit seasonally and stayed nearby.

Due to overcrowding, this account goes, Knox eventually established a location for the nonwhite inhabitants known as Peterborough, in present-day Warren, where a mixed-race community grew.

Whatever the true history of the field along Thatcher Street, Mitchell hopes to find out this month whether anything of interest has been left behind. He and some associates plan to dig 50 to 60 of the “test holes.”

“You checkerboard an area. You lay out a grid of some kind, or lines, or transects, where you set your test pits every 10 meters,” Mitchell explained. “You bring the material home, whatever it is you find, whether it’s a nail from yesterday or something else. You wash it, clean it, process it, analyze it, figure out what you’ve got, and then you figure out what else needs to be done, if anything.”

“In this case, it’s: let’s just see if there something there, and then we can talk about what we all might do,” he said.

On May 7, Mitchell was on the site along with Randy Harvey and Ryan King, who have worked with him on other digs. Every few feet, they dig a pit, sifting through each shovelful of mucky soil, picking out pieces of ceramic, brick, nails or bone, or finding nothing at all. Then they cover it back up, record what they have found, and move on. Each and every fragment that appears to have a human origin is collected, carefully washed, sorted and analyzed.

Two days earlier, a team of four had already completed one line of small pits along one edge of the field. Mitchell said there had most likely been a structure at one corner of the field, littered all around with fragments of what he supposes are 19th-century pieces of ceramic and glass.

In one pit, however, they found a long, hand-hewn log. Mitchell did not guess at its significance, but it may merit further investigation.

Mitchell and a small crew plan to do test work on the site through June. In any case, Mitchell said the team was restricting themselves to identifying what may have been in the field without delving too deeply.

Both Mitchell and Harvey likened these digs to painting – each pit is a stroke of paint; as the effort progresses, a bigger picture forms. Mitchell said he hopes that picture, should it reveal anything of interest, could guide later investigations by someone with greater resources and significant time to spend on the site.

Mitchell emphasized that he was grateful to the property owners and to the town, which mowed the field and helped track down historical background along with the historical society.

After identifying their findings, Mitchell and Bock will move on to seek out another 18th-century site somewhere along the St. George River.