High above the floor of the Mojave Desert, a pair of UCLA undergraduates and a Los Angeles television producer scoured a rocky cliff looking for a specific ancient etching in stone.

Almost anywhere in America, they would have had trouble finding a single petroglyph, but not here, among some of California's most dazzling rock art.

Squiggles, dots, stars, half-moons and big horned sheep - everywhere the climbers looked they saw images etched in stone possibly thousands of years ago. But the one petroglyph they sought eluded them.

"This is like finding a needle in a haystack," groused Gwen Hardwood, a volunteer trying to direct the climbers 20 feet above the ground.

Then 20 minutes later, Tracey Oh, a UCLA junior majoring in design, peered deep into the shadow of an overhanging boulder and let out a gasp.

"Here it is! Here it is!" she hollered when she recognized the sketchy petroglyph overlooked by an earlier crew attempting to document this rich and mysterious tapestry.

Out came 35-millimeter and digital cameras, and within moments the volunteers had recorded for posterity "rock art element 330."

Another weekend of petroglyph-hunting was off and running at Little Lake, the site of the most ambitious project ever undertaken by California's oldest and most prestigious rock art research facility - UCLA's Rock Art Archive.

For the past five years, archive volunteers have converged on this four-square-mile site beside a picturesque lake just north of Ridgecrest to map, photograph and cross-reference thousands of rock art elements, some believed to be the nation's oldest.

With just one more trip scheduled before issuing a preliminary report, the team is close to completing what may be the largest rock art-mapping project ever undertaken in California.

While the timetable is hotly disputed, archaeologists believe the spring-fed lake and a nearby source of obsidian drew at least two separate tribes of Native Americans and possibly bands of nomadic traders as well. Working apart and together, these tribes then developed a distinctive style of rock art. The images cover a rocky outcropping at the site's center, rock walls along the lake's shores and at both ends of a long slope of volcanic boulders.

"We have a busy intersection here, an oasis where people came together from different places and created something new," said Jo Anne Van Tilburg, a noted UCLA archaeologist and director of the archives at the Cotsen Institute of Archaeology. "It's very California."

The 20-odd aerospace engineers, computer programmers, teachers and other volunteers, many of them students recruited from Van Tilburg's UCLA Extension rock art classes, are racing against time and seismic fate. In 1997, touring a cave laced with pictographs filled them with wonder. By the following year, a 5.2-earthquake at nearby China Lake Weapons Center had closed the cave's mouth. The area, described in USA Today as "among the quakiest places on earth," has been shaken by more than 8,000 temblors in a single six-month period, threatening what some archaeologists believe is the site of the nation's oldest example of rock art.

"If it were in France or Spain, the government would be spending a massive amount of money to preserve and document this site, but when it comes to Native-American remains, the commitment is lacking," said David Whitely, a Fillmore-based archaeologist and author. "It's great that the archive is there. Nobody else would do this work."

Since its founding 25 years ago, the archive has amassed the world's largest repository of information on California rock art. The collection boasts slides, sketches, videotapes, maps and - more recently - digital images of rock art from more than 10,000 sites across the state. A significant portion of these sites has now been damaged or obliterated by vandals, development and natural forms of wear and tear such as earthquakes and erosion.

In the field, volunteers - mostly UCLA students and alumni - begin by affixing a temporary sticker with a number to each example of rock art. Volunteers carrying Global Positioning System equipment pinpoint the precise location of the art. A team with professional laser surveyor equipment then measures each artwork's elevation and distance from its nearest neighbors. All the data will later figure into an array of tables and charts.

While one team shoots close-up photographs of key petroglyphs with a digital microscope, another takes readings with a special meter that measures the reflection of light off etched rocks, a detail that may help pin down dates for the petroglyphs.

UCLA alumnus and longtime volunteer Gordon Hull sets up a makeshift digital photo lab in a nearby tent where he can examine the digital photographs. If photos still fail to capture all the wonders of a particular painting or etching, Van Tilburg will dispatch an artist to make a tracing or drawing of the image.

The hardest task falls to Oh's five-person crew, who must scramble over rocks to find specific petroglyphs, some no bigger than a thin vertical line, that had been previously mapped but apparently not photographed. During one grueling eight-hour day, they managed to find only seven of the 46 missing petroglyphs. Even though hours of searching produced nothing, nobody complained.

Back in the lab, work-study students and more volunteers feed the information into a computerized database. Is the image human-like, they wonder, or does it represent game? On what type of rock was it created? Has the piece suffered wind or water erosion?

"The detail is amazing," said volunteer and UCLA alumna Audrey Kopp, "but that's archaeology."

Added Van Tilburg: "In archaeology, overkill is a good habit."

She should know. An authority on Easter Island, Van Tilburg is trying to bring the same professional standards she uses to analyze the South Pacific monoliths to the study of California's rock art. Traditionally, dedicated amateurs have collected most of the state's rock art data, which unfortunately can be spotty and unreliable.

"Ninety percent of the data collected by other recorders or archives consists of a brief map and maybe a photo or sketch, but modern researchers need more detailed and objective data," Van Tilburg explained.

Only one other organization in the country observes the same standard of accuracy as UCLA's Rock Art Archive, she said, and it's a commercial lab that would charge roughly $40,000 for what the Little Lake team has accomplished for about $2,000, mostly in work-study salaries.

Van Tilburg hopes the information will shed light on the site's long-standing mysteries. Is the rock art a vestige of "hunting magic" practiced by prehistoric hunters hoping for more game? Or was it created more recently by shamans in altered states of consciousness induced by fasting, water deprivation or ingestion of massive quantities of tobacco? Until the archive completes its work, there is not enough data to know.

"We have a complex and conflicting picture for this site, and our contribution will be to collect a standardized data set that all researchers can use," she said. "This place will set rock art on its ear."