This particular weekend, Van Tilburg has mustered a crew of more than 20 enthusiasts --many of them students from the rock-art classes she teaches at UCLA Extension -- to help clear up lingering questions in the data from earlier visits. Crews are mapping, measuring and photographing at three locations, scrambling up cliffs and peering at rock faces. "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 "vision quests," in which shamans sought to draw on the powers of the world around them by inducing hallucinations. The petroglyphs at Little Lake appear to offer some evidence for both theories, Van Tilburg 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.
One crew is at work near a lakeside picnic area that has what Van Tilburg describes as "a tremendous clustering" of images -- more than two dozen new ones are identified, photographed and mapped before lunch. Nearby, Debra Isaac, a UCLA design major who has become the archive's expert on image quality, works on a field test of a digital microscope whose high-resolution images could reveal more about patination, the process by which weather and microbes slowly darken the white bruising that makes up petroglyphs. 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 difference, the longer the petroglyph has weathered and the older it might be.