Los Angeles on a clear day from the Sam Merrill Trail (Hike 20)

      The Santa Monica Mountains

      We start with the Santa Monica Mountains, which rise abruptly from the Pacific shoreline west of (or up the coast from) Los Angeles. They, along with the San Gabriel and San Bernardino Mountains, are part of the Transverse Ranges, so named because they trend east-west and stand crosswise to the usual northwest-southeast grain of nearly every other major mountain range in California. This anomaly, it is thought, is largely due to compression along the San Andreas Fault. There is a kink in the San Andreas Fault north of Los Angeles where the fault, running southeast from the San Francisco Bay Area, jogs east for a while before resuming its course toward the southeast. Compression against this kink has caused the land south of it to crumple and wrinkle upward. The devastating January 1994 Northridge earthquake was just one small episode in the slow but fitful uplift of the Transverse Ranges.

      Compared to other Southern California ranges, the Santa Monicas are modest in size—barely more than 3,000 feet high—but their rise from the sea is dramatic. They are a shaggy-looking range, clothed in tough, drought-resistant vegetation that falls into two principal categories: coastal sage scrub and chaparral. The coastal sage scrub plant community lies mostly below 2,000 feet in elevation, on primarily south-facing slopes in the Santa Monica Mountains and elsewhere in the coastal ranges of Southern California. Characterized by various aromatic sages (California sagebrush, black sage, and white sage) along with buckwheat, laurel sumac, lemonade berry shrubs, and prickly pear cactus, sage scrub is fast disappearing in the Santa Monicas and elsewhere as urbanization encroaches on it. Much of the sage-scrub vegetation is dormant and dead-looking during the warmer half of the year but green and aromatic during the cool, wet half.