Arroyo Seco Creek to Agua Tibia Mountain

This rigorous and rewarding all-day trip leads hikers from a deep, brushy canyon to a pine-clad mountain in the southern Peninsular Ranges. Agua Tibia Mountain, the western end of a long hogback ridge known as the Palomar Range or Agua Tibia Range, supports cool forests of Coulter pine on its upper slopes and offers relief to the hikers who slog for miles up the mountain’s hot, brushchoked lower slopes. The Agua Tibia Range is one of many San Diego and Riverside County mountain masses belonging to California’s Peninsular Ranges province. Fundamentally, these are southern California’s coast ranges, which extend southward from the Los Angeles Basin for the entire length of Baja California. Coulter pine (or big-cone pine), a conifer indigenous to California and northern Baja California, forms extensive forests along the upper reaches of the Agua Tibia Range and other relatively high ranges in San Diego County. It inhabits dry rocky slopes between 3,000 and 7,000 feet in elevation, growing in pure stands or mixing with other conifers and oaks.With needles in bundles of three, it resembles the ponderosa and Jeffrey pines. However, its distinguishing characteristic is its large cones. Reaching 10 to 14 inches in length and weighing as much as five pounds, the heavy, clawed cones are the largest of the American pine cones.