NU'ALOLO KAI, Kaua'i — The fire cliff Kamaile towers over this ancient coastal village where archaeologists say the stone remains of hundreds of years of early Hawaiian habitation hold amazing secrets.

After 10 years of intensive mapping at the site, much of it aided by thousands of hours of volunteer labor by the Na Pali Coast 'Ohana, scientists have uncovered a unique archaeological assemblage, with suggestions of the Marquesas, hints of the mystery island of Mokumanamana and other fragments from the rugged Na Pali coastline's past.

"This site was something extremely important at some time in its life, but we can't find out anything about it," said Alan Carpenter, an archaeologist with the Division of State Parks who oversees the work. He and a range of experts in Hawaiian culture are trying to divine meaning from the arrangements of stones, while researchers such as University of Hawai'i Hawaiian language instructor Keao NeSmith search Hawaiian newspapers from the 1800s for clues.

Nu'alolo is now part of the expansive Na Pali Coast State Park, a 10-mile stretch of plunging cliffs, hanging valleys and sweet beaches. To the northeast is the hanging valley of Nu'alolo 'Aina, and around jagged Alapi'i Point, the narrow strip of Nu'alolo Kai. It is accessible only by boat. There is no trail into Nu'alolo Kai.

It has long been known as an ancient fishing village site, famous for a log ladder used to climb part of the cliff trail between the two Nu'alolos — and for Kamaile — more than 1,000 feet high and the site of the 'oahi ceremony, in which people would carry sticks of light wood to the top of the cliff at night, set them afire and toss them into the trade winds. The winds would keep the sparking, blazing brands aloft, a spectacle for people on shore and in canoes. Hence, the name fire cliff.

There's more to Nu'alolo Kai than that, but for more than a century, much of the other history has been hidden under a dense cover of weeds.

For the past decade, volunteers with the nonprofit Na Pali Coast 'Ohana, working with machetes, hand saws, chain saws, rakes and a lot of labor, have been peeling back the vegetation, revealing an amazing cultural landscape that raises more questions than it answers.

"It is nice to see a valley come back from obscurity," said O'ahu archaeologist Moana Lee, who volunteers her time to work here.

One of the key sites of Nu'alolo Kai is a vast ceremonial complex whose full extent had never been recognized before, Carpenter said.

At the site's highest level, in the shade of Kamaile, is a high-walled heiau or temple, facing true north. Downslope are house platforms believed to have belonged to high-ranking individuals. There are small shrines. Twin formal platforms — perhaps performance stages — were built with their surfaces sloped forward, perhaps to provide spectators at lower elevation with a better view.

There is a small well within the complex, and near the well is an enigmatic feature that looks like a stone-age swimming pool. The four-sided pond, roughly 30 by 40 feet, is lined with stone, has a ledge near the waterline, and its floor is paved with flat stones. It has been dug more than 10 feet below the surrounding landscape, just deep enough to pierce the natural water table.

Today, it has been filled with sediment, and water-loving plants such as taro, ferns and reeds grow in it. Was it once a taro patch, and if so, why the paving? Or a bathing pool, a reflecting pond, a ceremonial feature? Nobody knows.

Surrounding all these are burial structures, house sites and stone walls, their functions not fully understood. Various archaeologists have visited and remarked on the similarity of some of Nu'alolo Kai's features to structures elsewhere in Polynesia. One site with upright slabs is reminiscent of the upright stones on Mokumanamana in the Northwestern Hawaiian Islands.

Billy Fields, a master in the construction and renovation of Hawaiian stonework, said some of the construction features of Nu'alolo's rubble stone walls are quite unusual for Hawaiian stonework.

"I was confused when I first looked at it. I thought I was looking at something that had been rebuilt. But then I realized this is how this builder did it," he said.

Fields visited the site for the first time Friday to provide advice on the preservation of structures that are falling down, often because of feral goats that knock stones loose. He has proposed training Kaua'i volunteers in Hawaiian stone construction techniques. On Friday afternoon, on the rocky Nu'alolo shore, he gave a workshop on lithic building techniques to members of the Na Pali Coast 'Ohana.

For the past 10 years, 'ohana volunteers have visited between two and five times a year, with groups of up to 15, for five days at a time. They are delivered and collected by the tour boat companies that ply the coast.

"The beauty attracted us. It has its own special mana," said Sabra Kauka, an educator, Hawaiian cultural practitioner and president of the 'ohana. "We had been working in (the larger, trail-accessible) Kalalau, but the impact of the people there was huge. Every year when we came back, we were dismayed because there was just as much trash as there was the year before. This place (Nu'alolo) is fairly well protected from impact. You could work and make progress."

Volunteers have worked thousands of hours in the heat, for the experience of isolation, the beauty and the opportunity to restore something culturally important, she said.

For the state, the collaboration is hard to beat. The 'ohana gets what money it needs through grants and corporate sponsors — not from the state.

"Very, very few state resources have been used. It's almost free," Carpenter said.

Among the private donors is developer Brookfield Homes, which funded the trip by Fields from his Big Island home.

But while there is interest in stopping the deterioration of stone structures and perhaps doing some restoration, deciding how to proceed is problematic, Carpenter said. For one thing, Nu'alolo is a landscape that changed over time. Older structures have often been partly dismantled to provide stones for newer ones. Some structures stand on top of buried structures. Many burial cairns, for instance, appear to have been built with rocks from nearby walls.

For Kauka, the culture and the archaeology are inseparable, and she seems proud that Nu'alolo Kai's long period of abandonment is over.

"Our purpose is to restore the dignity," she said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.