Clambering Up a Cliff to Record the Fading Handiwork of Man

By LAWRENCE BIEMILLER

Every so often, Jo Anne Van Tilburg loads up her S.U.V. and heads north out of Los Angeles, past the last mall, the last freeway traffic jam, the last tract-housing development. She drives over the San Gabriel Mountains, turns right at a town called Mojave, and crosses miles of scrubland punctuated by sagebrush and Joshua trees. Eventually she leaves behind history as we know it -- industry, mass communication, the relentless advance of science -- and arrives at Little Lake.

Little Lake is a shallow, spring-fed stretch of water beneath an imposing escarpment of black basalt. In its own right it is remarkable, an unspoiled oasis of grasses and ducks in a region where most of the features called "lakes" are just dotted lines on the map, explained by an adjoining "(Dry)." But what makes Little Lake interesting to archaeologists like Ms. Van Tilburg are hundreds of drawings made centuries ago by American Indians who either visited or lived by the lake.

The drawings are petroglyphs, made by bruising a rock face with another rock so that a whitish image appears. Some are clearly identifiable -- as mountain sheep, for example, and atlatls (pronounced "AT-LAT-uls"), which were throwing levers used to launch short spears. Other images are geometric -- pirals and concentric circles, for instance. Still others are open to interpretation -- some rectangles might, or might not, represent medicine bags in which tribal shamans carried items that they believed had special powers.

The mix of subjects and styles here is particularly intriguing, says Ms. Van Tilburg. She is well known in archaeology circles for her research on Easter Island's monoliths, but she is also director of the Rock Art Archive, which is part of the Institute of Archaeology at the University of California at Los Angeles. At Little Lake, she says, drawings apparently made by the Owens Valley Paiute -- whose culture was centered north of here -- appear near artworks in the style of the Coso Shoshone, whose culture arose to the south. Meanwhile, dozens of petroglyphs adorning a cliff at the south end of the site seem to have been done by long -- ago travelers. Abundant obsidian shards suggest that Little Lake may have been a meeting place for traders dealing in the black, glassy substance, which was used for knife blades and arrowheads. Ms. Van Tilburg describes the site as having "a fluorescence of art and activity."

For years, she says, most archaeologists ignored rock art, here as well as elsewhere, but that has begun to change. While the rock-art archive at U.C.L.A. contains numerous collections of rock -- art photographs and other data, it is also an organization of volunteers who come to places like Little Lake with digital cameras and laser measuring devices to document and photograph rock art and create modern databases for scholars. So far the archive has produced searchable CD-ROM databases for three sites. "In the end," Ms. Van Tilburg says, "an archaeologist is a person with a database."

This particular weekend, she has mustered a crew of more than 20 rock -- art enthusiasts, including a high-school student and several retirees, to help clear up lingering questions in the data from earlier visits. Documenting enigmatic images on large expanses of rock is hard work -- some images can be seen only by climbing up the earthquake-fractured faces of cliffs, and some are so faint that they're impossible to spot if the light strikes them the wrong way. It's not surprising that mistakes happen: Identification numbers get confused. Images are photographed but not mapped, or mapped but not photographed.

So Ms. Van Tilburg has crews mapping, measuring, and photographing at three locations here today. "Nobody before us has put this much energy into this area," she says as she makes her rounds, noting that corrected data from her volunteers will give scholars an important opportunity to test some widely held theories that "are based on a cursory examination of the data." Little Lake is "an anomaly," she adds, and intensive scrutiny -- along with the latest technology -- may yield surprises. "This place," she says, grinning behind her sunglasses, "is going to set rock art on its ear."

Among the theories that need testing are two competing hypotheses about the origins of the petroglyphs. The older theory holds that the drawings are related to "hunting magic" -- hence the sheep -- and were probably made before A.D. 1200, when the sheep disappeared from this area. The newer theory suggests that the images are mementos of shamanic "vision quests," in which shamans sought to draw on the powers of the world around them by inducing hallucinations. "The vision became your spirit helper, which you immortalized with an image," Ms. Van Tilburg explains.

The petroglyphs at Little Lake appear to offer some evidence for both theories, she says. But crucial information is still missing, in particular reliable estimates of the images' ages. The petroglyphs, she says, "could have been made at any time" between the beginning of human activity here, some 10,000 years back, and 1860.

Little Lake is owned now by a duck-hunting club -- which is fitting, Ms. Van Tilburg suggests, because the site's location under Pacific migration routes has always been part of its importance. Ducks and other birds, along with their eggs, were no doubt a source of food for Indian families. What's also interesting, she says, is that the site's past is a metaphor for present-day California -- people from different cultures came together at an oasis, aesthetic concerns were part of daily life, and every now and then they had earthquakes.

One crew of today's volunteers is at work near a lakeside picnic area that has what she describes as "a tremendous clustering" of images -- along with stone barbecue grills that have been built within inches of the petroglyphs. The volunteers are documenting images that haven't been previously cataloged; more than two dozen turn up before lunch. The work involves searching rock faces, taping identification numbers beside petroglyphs, and photographing them. The images also are mapped with hand-held laser surveying equipment.

A U.C.L.A. design major who has become the archive's expert on image quality, Debra Isaac, works nearby on a field test of a Keyence digital microscope that Ms. Isaac and Ms. Van Tilburg say could produce clues about the ages of the petroglyphs. In theory, the microscope's high-resolution images might reveal more about patination, the process by which weather and microbes slowly darken the white bruising that makes up petroglyphs. But the microscope is the size of a desktop computer, and it needs 120-volt power. A converter lets a Keyence sales executive, Scott Garner, run the microscope from an outlet in his S.U.V., but the converter can't power both the machine and the high-intensity light that its most powerful lens requires. Extension cords snaking over to the duck club's bathroom solve the problem for the moment, but clearly there are limits to the machine's utility in the field.

Over at Atlatl Cliff, meanwhile, an aerospace engineer named John Bretney is scrambling over a rockfall to test another advanced technology -- a hand-held spectrophotometer, which he hopes will offer precise readings of the difference in color between the petroglyphs and the surfaces on which they were made. The less the color difference, the older the image, all other things being equal. Atlatl Cliff has some 90 portrayals of the throwing levers, as well as an assortment of anthropomorphic figures and other attractions. "Once we get these things arrayed" in the database, Ms. Van Tilburg says, "you're going to see the transitions." Her own working premise, in fact, is that the images aren't really meant to be atlatls. "My thesis is that these are shorthand representations of the human form -- human and atlatl combined." She points out a petroglyph that shows "an atlatl holding an atlatl with arms -- that's the key to this whole place."

Later, at the far end of the lake, several teams of volunteers clamber over the cliff where a profusion of petroglyph styles suggests that travelers added many images as they were passing through. Ji-Son Choi, a U.C.L.A. junior, is high among the rocks with Elizabeth Edmunds, a student at South Torrance High School, searching for petroglyphs that have been mapped but not photographed. Even with help from spotters on the ground, the job is a challenge, in part because images appear and disappear as the angle of the sun changes. Already, Ms. Choi says, they've lost sight of a four-figure group -- the two students dubbed it "the Backstreet Boys" -- that they know is on the rock face right beside them. Down below, a retiree named Audrey Kopp is peering at the base of the cliff, certain that petroglyph 19-103 -- of which she holds a photocopied picture -- is in front of her. The task sounds easy enough: Study the pattern of fractures in the photocopy, then search the rock face for its match. A simple matter of pattern recognition. After 10 minutes Ms. Kopp gives up, but a reporter stands glued to the spot for five minutes more, refusing to concede that the mysterious image has willfully vanished before his eyes.

Still, the day is a success. By the time the sun sets and evening's chill sets in, many missing petroglyphs have been located, and many others have been mapped for the first time. Ms. Van Tilburg's volunteers gather at the lakeside picnic area for a potluck dinner featuring stew, vegetarian chili, pasta salads, roast chicken, and a delicious tuna loaf concocted by Natalie Ferriz, a French archaeologist who is among the volunteers. Brilliant stars and a waxing moon illuminate the lake, and choruses of frogs serenade the party, gathered close around a campfire with cups of wine and tea. Ms. Van Tilburg is laughing and telling stories. In the shadows, mountain sheep drawn centuries ago keep watch.