The next morning, we pile back into the Suburban, the archaeologists leading the way in their four-wheel drive vehicles, and head north toward the mountains. Just a few miles out of town, we leave the Trans-Peninsular’s blacktop for a gravel road that threads inside the jumble of volcanic peaks to our west.
An hour turns into two. The cactusstudded peaks of the Sierra de Guadalupe rise nearly 5,000 feet on all sides. Four thousand feet below us, dry riverbeds, remnants of the winter rains and hurricanes that sometimes drench the landscape, braid through the bottom of each valley. Ficus trees, flowering shrubs and dozens of varieties of cacti thrive here, including the prickly cirio, looking like a green, inverted carrot drawn by Dr. Seuss. Lizards skitter ahead of us along the gravel track. “This place is a maze,” Crosby says. “It’s easy to get disoriented and in trouble.”
Finally, after several hours, we come to an outpost called Rancho de San Sebastian, a cluster of cinder-block-andplaster houses backed against a tall peak. We climb stiffly out. A few of the ranchers emerge from whitewashed cottages to inspect us. The people of San Sebastian don’t see many visitors, and they’re wary.
Once we exchange greetings, we begin trekking up an eroded, dry riverbed, then up a narrower dry-creek canyon, called a cañada. The canyon walls are dauntingly steep, sending a few of us sliding downhill in small avalanches of scree. After at least a half hour of scrambling under low brush up the incline, we emerge along the brow of a mountain. There, protected by an overhanging cliff, is a shallow respaldo shelter.
In the one nearest us, two vultures, rendered in black pigment, rise overhead, their wings spread. Three human figures painted in red and black—along with faded but recognizable representations of deer and bighorn sheep—grace the back wall. As with all the Great Murals, the figures depicted are, for the most part, life-size. Each seems urgent and fresh, with a touching immediacy transcending 3,500 years.