In early spring, the California mountain town of Julian sits suspended between seasons. At more than 4,000 feet, up in the Cuyamaca Mountains, it rests among coastal live oak woodlands and Coulter pine forests. Snow sometimes dusts the surrounding slopes, melting by afternoon into damp earth as manzanita and mountain lilac begin to flower. Along Main Street, the mingled scents of woodsmoke and apple pie drift from storefronts. It is here that my journey along State Route 78 begins, following its long eastward descent from the mountain forest into the stark badlands of Anza-Borrego Desert State Park, then skirting the southern edge of the Salton Sea, crossing the Algodones Dunes and continuing toward the Colorado River — a 140-mile corridor spanning one of the most dramatic ecological transitions across public lands in the American Southwest. This road trip continues a series exploring California’s overlooked scenic highways, inspired in part by artist Earl Thollander’s “Back Roads of California,” whose sketches and travel notes celebrated a slower way of seeing. After tracing Highway 127 along the edge …