FLAGSTAFF, Ariz. — The Navajo Nation is seeking full control of one of the only national monuments entirely on reservation land, the majestic Canyon de Chelly and its hundreds of ancient rock carvings and paintings.

Since 1931, the National Park Service has been charged with preserving thousands of artifacts and ruins within the monument's towering red sandstone walls, while the land revered by the Navajos as sacred remained tribally owned.

Now the Tribal Council wants full control of the 131-square-mile monument in northeastern Arizona and the more than $1.8 million in federal funding that goes with it. Doing so would strengthen the tribe's sovereignty and demonstrate its expertise and competence in administering tribal land and resources to benefit Navajo people, supporters say.

"It's a site that is very important in terms of not only the historical but also the cultural and spiritual aspects of the nation," said Arvin Trujillo, director of the tribe's Division of Natural Resources. "We are moving in a direction where we're becoming better equipped to take over some of these monuments."

The Tribal Council was to vote on legislation to seek the transfer of the canyon to the tribe during a special session in Window Rock on Thursday. But tribal lawmakers put off the vote until public hearings could be held on the issue.

Canyon de Chelly, near Chinle, in the heart of the Navajo Nation, has been inhabited for some 2,000 years. Artifacts and cliff dwellings lining the canyon walls date from the 4th to 14th centuries. The Navajo call the canyon "tsegi," which means "within the rock," and about 80 Navajos live in the canyon.

Canyon residents have been divided over the years on how much involvement they believe the Park Service should have in overseeing the monument. Some favor a joint management plan, while others want the Park Service out of the picture.

The Park Service has various agreements with tribes whose reservations lie within a national monument. Some allow tribes to manage a portion of park, rebuild trails, restore watersheds and hunt on tribal land, for example.

In South Dakota, the Park Service is thinking about returning complete control of the South Unit of Badlands National Park to the Oglala Sioux. In 2000, Congress passed a law that allows the Timbisha Shoshone Tribe to completely manage tribal trust land within Death Valley National Park. At Everglades National Park in Florida, the federal government has set aside a special reserved area for the Miccosukee Tribe within the park.

Patricia L. Parker, chief of the Park Service's American Indian Liaison Office in Washington, D.C., said tribes are encouraged to take a more active role in managing their lands. But no national monument has been completely turned over to a tribe, as the Navajo Nation is asking, she said.

"If I were the tribe, I would take a good look at to what extent would the lands be better protected, what would be the benefits locally for having it be a tribal park rather than it be a national monument or park, and I'm sure they're weighing the benefits," she said.

The Park Service, which employs about 25 people at Canyon de Chelly, says the Navajo Nation has every right to seek full control of the canyon, believed to be the birthplace of many tribal deities. Congress would have the final say.

"There would be a lot of coordination that would need to happen and a lot of discussion with lawyers to figure out how things would transfer," said Canyon de Chelly superintendent Tom Clark. "It would be a big process, but obviously doable."