Hundreds of stones from a mission-era foundation spanning more than a football field in length will be preserved and possibly reassembled rather than dumped, a Ventura preservation group said this week.

The nonprofit San Buenaventura Conservancy hastily arranged a deal with homebuilder Olson Co. and the Museum of Ventura County to haul the stones to museum grounds, where they will be stored and possibly incorporated into a multimillion-dollar museum expansion project.

The stones and other historical artifacts were recently unearthed during excavation for a 172-unit condominium project at Santa Clara and Junipero streets in downtown Ventura. The 3.6-acre site is across the street from the museum.

"We are moving the stones at our cost, and we are happy to do it," said Bill McReynolds, Olson's director of development.

The river stones, culled from local watersheds, are believed to date to the late 1700s, when they were assembled with mud by American Indians into a foundation wall some 400 feet long, 3 feet wide and 3 feet deep. The foundation supported a garden wall that once enclosed citrus and olive orchards kept by friars at the San Buenaventura Mission.

The preservation group sprang into action last week after learning that virtually all of the stones were set to be discarded once an archaeological firm finished recording significant historical artifacts from the site, said conservancy member David Armstrong, a Ventura land-use consultant and former city redevelopment consultant who largely arranged the deal to preserve the stones.

Olson's archaeologist, John Foster, said the integrity of the foundation had been "severely compromised," but the conservancy's Armstrong felt the removal of the stones "was like dumping a part of Ventura's history."

"We were in a panic because the archaeologist was nearly finished, and we were afraid the stones were going to be hauled off" to a dump, Armstrong said. "We never wanted to slow the housing project, but we felt that if we could find a place to store them closer and at no additional cost to Olson, then we could strike a deal. Fortunately, the museum got on board, and they (Olson officials) said absolutely.' "

An expansion of the historical museum is expected to break ground later this year. The stones likely could be incorporated into a water feature and a rock wall, said Greg Smith, co-chairman of the museum's capital campaign. "I think it's a terrific solution," he said.

The excavated lot most recently held the headquarters of the Ventura Unified School District. Before that, it was an elementary school.

In pioneer days, it was the home of the county's first administrative buildings. Foster's archaeologists have uncovered the brick foundation of the county's first jail, the courthouse's stone foundation and outhouses, as well as shells, a pestle and bead-making materials from the native Chumash who inhabited the land before the arrival of Spanish missionaries. Many of those artifacts also will be housed at the museum.