Berkeley - More than 100,000 artifacts from three centuries of military life have been dug out of the ground at San Francisco's Presidio by University of California, Berkeley, archaeologists.

The archaeologists also have found some extremely early refuse pits that may date to the earliest days of the original Spanish fort established in 1776. The pits provide new information about how colonists were using the Presidio lands when they first arrived in San Francisco.

These and other findings from excavations at the Presidio are being reported this month by UC Berkeley's Funston Avenue Archaeological Research Project, which continues its work this summer. Sponsored by the Presidio Trust in cooperation with the National Park Service, the project is the first to examine the daily lives of military families in the Funston Avenue officer's quarters.

On Tuesday, June 27, the public is invited to see the artifacts, meet the archaeologists and view the pits, walls and living floors of past centuries at the Presidio. The archaeological open house will be held at the Funston Avenue dig from 1 p.m. to 7 p.m. and is timed to coincide with the June 29 anniversary of the establishment of the city of San Francisco.

Barbara Voss, co-coordinator of the project and a UC Berkeley graduate student in anthropology, said the dig had exceeded expectations. "We thought we would find a lot of material scattered around the surface. Instead we found these deep, dense features that are far richer and older than we ever expected."

Just how old the deepest layer is remains to be seen, said Voss. It could be part of the original 1776 occupation because it was discovered beneath a foundation constructed in the early 1800s as part of an expansion of the Presidio.

"The pieces of ceramic we found there date to the late 1700s," said Voss. "It's hard to tell if this is from the absolutely first settlement, but it could be. It is certainly older than any other deposit found so far in the Funston area."

Voss said that a fine-grained stratigraphic analysis of the site this summer should give more information on the early find. A study of ceramics from the pits that are known to have been imported from Mexico in the late 1700s and early 1800s may produce a more exact date.

The discovery consists of five pits, probably dug originally for clay to make bricks and later used as refuse dumps. In the expansion of the Presidio of the early 1800s, the pits were topped with fresh clay and foundations were laid over them.

The excavations also have shed new light on the lives of San Francisco's first colonists who came here to set up a military outpost and establish a Spanish colony, said Voss.

"Soldiers and their families lived within the fort. Most of the population were women and children," she said. Isolated for most of the year, the "outpost community of about 200 to 300 people had to develop its own way of living, learning how to cope on a cold, windswept, foggy, barren plateau."

Voss said that tree-planting at the Presidio was undertaken by the U.S. Army in 1880 to break the wind and replicate an eastern woodland. But before that, the area was bleak.

Residents who lived there had to become self sufficient, perhaps even making their own ceramics, because ships arrived only once a year at this outpost of colonial Spain.

American occupation dates from 1847 and is evident in the sudden appearance of manufactured goods, including manufactured soda water bottles, according to Amy Ramsay, co-coordinator of the project, and also a UC Berkeley graduate student.

It was a small outpost throughout the Gold Rush years. Speculation has it that many of the soldiers may have decamped in the night, headed for the gold fields.

During the Civil War, life at the Presidio bloomed again, said Ramsay. Excavations have turned up a substantial amount of intact Civil War material, including ceramics, costume jewelry, smoking pipes, pieces of ammunition, a live bullet and a tiny rhinestone the size of the head of a pin.

Ramsay said that at first the American houses faced west toward the Pacific. Later they were changed to face east toward the new City of San Francisco.

One good reason to change the orientation of the houses, she said, would have been to protect front parlors from the ever-blowing sand. It would be years before tiny saplings planted in 1880 would become the dense woodland that now covers Presidio lands.

UC Berkeley's dig is among the first steps taken by the Presidio Trust to develop an archaeological management plan for the park, as part of its mission to preserve the park's natural resources while making it self-sufficient by the year 2013.