Researchers on a rare expedition to a now uninhabited rocky outpost north of the main Hawaiian islands found a partially finished human stone carving and the remnants of what may be a craftsman's workshop.

The findings at the remote Mokumanamana island, about 460 miles northwest of Honolulu, were part of the most extensive archaeological survey of the tiny outcrop in 85 years.

University of Hawai'i anthropology doctoral student Kekuewa Kikiloi spent 18 days on the 46-acre island along with Anan Raymond, a U.S. Fish and Wildlife Service archaeologist.

The inhospitable island lacks fresh water, trees that would provide cover, and is continually buffeted by wind. It's frequented by seabirds, but is otherwise desolate save for the ruins of ancient heiau, or shrines, that line the top of a ridge running along the spine of the island.

"It's somewhat of an archaeological mystery as to how people survived on this island in the past and constructed these huge monuments," Kikiloi said yesterday.

The newly discovered carving resembles other stone figures found on Mokumanamana during a trip to the island sponsored by Hawai'i's provisional government shortly after the U.S.-backed overthrow of the Hawaiian monarchy in 1893.

That expedition brought several figures to the main islands, most of which are now at the Bishop Museum.

Kikiloi said it's not clear what the images were used for, but they're unlike any other objects in the Hawaiian islands.

In general in Hawaiian tradition, he said, images are often used as a focal point during prayer and worship of gods.

The partially unfinished figure found on this trip has a blank face, as though the artist didn't gotten around to carving facial features. It also appears that its left arm has broken off.

The workshop was far from the heiau. Raymond said someone may have been working on the figure to take to a heiau and would have done so if it was finished.

It's unclear when humans lived on the island or if they had a long-term settlement there.

But Kikiloi said coral objects on nearby Nihoa, which he believes was a staging ground for the construction Mokumanamana's heiau, date to the 1500s.

Mokumanamana has an unusually high concentration of heiau — at least 34 on just 46 acres.

Kikiloi believes Hawaiians built the shrines there because Mokumanamana was considered the gateway to the afterlife. He said he plans to address this theory in his doctoral dissertation.

Mokumanamana lies on the Tropic of Cancer. This means the sun — which represents life and death in Hawaiian tradition — goes directly over the island on the summer solstice, the longest day of the year.

Moreover, the Tropic of Cancer is called "Ke ala nui polohiwa a Kane" in Hawaiian, or "The Dark Shining Path of Kane," and is often used as a metaphor for the path to the afterlife.

"When spirits separate from the body after someone passes away, they go on a second half journey to return to the source that everything is created from," Kikiloi said.

There are similar shrines, with upright stones, atop the highest peaks of Maui and the Big Island, on Haleakala volcano and Mauna Loa and Mauna Kea volcanoes, respectively.

Mokumanamana is one of the Northwestern Hawaiian Islands and is inside the Papahanaumokuakea Marine National Monument created by President George W. Bush in 2006.