Not far from portland along Maine's winding coast, someone has placed a neatly lettered sign on an otherwise undistinguished boulder. It reads: Popham Rock 1607. A play on Plymouth Rock 1620, some 200 miles south? Not entirely. A colony called Popham actually did precede the renowned Massachusetts settlement.

"Popham was the cornerstone in the foundation of English America," says Jeffrey P. Brain, 64, an archaeologist with the Peabody Essex Museum in Salem, Massachusetts, who is excavating the site of the forgotten colony. "The lessons learned were important to the later success of the Pilgrims."

Popham's value lies in its failure. Its remains, discovered only nine years ago, have been called one of the most significant archaeological sites in the country. Unlike Jamestown, Popham's successful sister colony in Virginia, whose footprint changed as it developed, Popham represents a unique, undisturbed time capsule of a very early North American settlement.

Each September since 1997, Brain has enlisted a few colleagues and some 30 volunteers and amateur archaeologists to work for three weeks at the mouth of the Kennebec River, about 25 miles northeast of Portland. This year's team included an epidemiologist, an engineer, a nurse, a sociology professor and a historian from England. Popham was named after its principal financial backer, Sir John Popham, and his nephew George Popham, the colony's president.

It was founded about 20 years after Sir Walter Raleigh's North Carolina colony disappeared in the 1580s, when, as the economic race with France and Spain heated up, England made another attempt to plant its flag in the New World. In 1606, James I granted a charter to a joint stock company to establish two colonies, one, Jamestown, on the southern Atlantic Coast, and the other, Popham, on the northern.

On May 31, 1607, about 100 men and boys set sail for the northerly destination. Discharged soldiers made up most of the colonists' ranks, but shipwrights, coopers, carpenters and a smattering of "gentlemen of quality" rounded them out. About three months later, the group landed on a wooded peninsula where the Kennebec River meets the Atlantic Ocean, and began building Fort St. George. In December, with winter coming and food scarce, half of the colonists returned to England. The next fall, after erecting several buildings, the remaining 45 sailed home.

Popham's rediscovery came about by two events a century apart. In 1888, a researcher for an American diplomat happened upon a map of Fort St. George in government archives in Madrid. Drawn and signed by Popham colonist John Hunt, it was likely snatched, or copied, by a Spanish spy soon after it arrived in England in 1608.

The only known detailed plan of an early English colony, the map contains sketches of trenched ramparts, a storehouse, a chapel and various buildings—in all, more than 15 structures. Though published in 1890, the map provoked little interest for 100 years, until Brain came upon a mention of the lost colony while vacationing in Maine.

At first "I thought it was some sort of local mythology," he says. "But it was historically known, and I decided it was time to look for it archaeologically."

Research led him to Hunt's map, which took him to Sabino Head, a windy promontory on the Kennebec. Topographical features seemed to match Fort St. George's modified star-shaped contours. Conducting a test excavation on the area in 1994, Brain and his team found a posthole after several weeks of digging. Baffled by not finding more postholes, he "fiddled with the map," rotated it 20 degrees and came up with a dead-on match with the landscape. "It was a eureka moment," he recalls. Soon the crew was "turning up one after another" of the three-foot-wide pine mold-filled holes, eventually 19 in all, outlining the 69-by-20-foot storehouse that Hunt had depicted on his blueprint almost 400 years before.

Archaeologists are still not sure how many of the map's structures were actually built, but so far, in addition to the storehouse, they've located parts of the trench wall and the "Admirals howse," and they have leads on the buttery, a storehouse for wine and liquor. During the second week of this year's dig, Kathy Bugbee, a retiree from Southport, Maine, unearthed an inch-long piece of decorated stoneware. A digger for seven years, she recognized the brown glazed fragment as part of a Bellarmine jug, a German-made container used throughout Europe to store liquor in the 16th and 17th centuries. In his on-site cache of artifacts, Brain found a wedge of Bellarmine that he had assembled from other fragments two years earlier. Bugbee's find slid easily into a gap in the piece to reveal a medallion motif. The jug's embossed seal reads: "1599."

In addition to Bellarmine, the site has yielded other ceramics, clay tobacco pipes, glass trading beads, bullets and tools, including a caulking iron, used in shipbuilding. The Popham settlers did succeed in constructing the Virginia, a small but durable vessel that would take them back to England and later make other transatlantic voyages.

At the admiral's house, the archaeological team turned up shards of delftware, more Bellarmine, fancy buttons, bits of etched wine glasses and jet beads—all reflecting the occupants' upper-class rank. A museum exhibition of Popham artifacts is planned for the colony's 400th anniversary in 2007.

The main reason for abandoning the colony, Brain theorizes, was a loss of leadership. Only one member of the group, George Popham, is known to have died at Fort St. George. (Jamestown lost more than half of its 120 settlers the first year.) But he was the colony's president, and on February 5, 1608, Raleigh Gilbert took command. Just 25, Gilbert was, according to one investor, "desirous of supremasy," "a loose life," with "litle zeale in Religion." Six months later, a resupply ship brought Gilbert news that he had inherited a title and an estate back in England. When Gilbert decided to return to England to collect, the others headed back with him. "They were headless, so to speak," Brain says. "English society was very stratified; people needed leaders." Bad relations with the Indians, the fear of another severe winter and the area's lack of easily exploitable resources, such as gold or other precious metals, also affected the decision to abandon Popham.

Most of the returned settlers disappeared into history; a few crossed the Atlantic again to try their hand at Jamestown. The Pilgrims who arrived 12 years later, landing at Plymouth, had obviously learned some lessons from Popham. "They settled farther south in a milder climate that was more familiar to them and more conducive to agriculture," says Brain. "They tried harder to work with the Indians. They also brought women and children.

"Luck had a lot to do with these early ventures," Brain adds, explaining that Jamestown, too, almost failed. Hit hard by disease and starvation, the 50 or so remaining settlers abandoned the colony in the spring of 1610 and were sailing home when they encountered a relief fleet and a new governor, who ordered them back to Jamestown.

While about half of the one-acre Fort St. George site is on state land, a key portion, including the chapel, is not. Brain would like to dig there for traces of George Popham's remains. Neighbors, however, have mixed views about a possible major discovery in their backyard. Worried that the state might seize their property or tourists overrun it, some have refused access.

But Merry Chapin, a teacher at nearby Phippsburg Elementary School, sees things differently. Every summer she brings her class of fifth graders to the site to talk with the diggers and even sift a little dirt. "It makes history much more real for them," she says. "When you can hold Raleigh Gilbert's 400-year-old buttons in your hand, it's a lot about wonder."