SOUTHERN CALIFORNIA SITS astride one of Earth’s most significant structural features—the San Andreas Fault. For more than 10 million years, earth movements along the San Andreas and neighboring faults have shaped the dramatic topography evident throughout the region today. The very complexity of the shape of the land has spawned a variety of localized climates. In turn, the varied climates, along with the diverse topography and geology, have resulted in a remarkably plentiful and diverse array of plant and animal life.

Living on the active edge of a continent has advantages and disadvantages that cannot be untangled. Like the proverbial silver lining in a dark cloud, the rumpled beauty of our youthful, ever-changing coastline, mountains, and desert redresses the ever-present threat of earthquakes, fires, and floods. Because much of Southern California is physically rugged, not all of it has succumbed to the plow or the bulldozer. When you’ve had the pleasure of hiking beside a crystal-clear mountain stream minutes from downtown L.A. or cooling off in the spray of a cottonwood-fringed waterfall just beyond suburban San Diego, you’ll realize that not many regions in the world offer so great a variety of natural pleasures to a population of many millions.

Let us, in the next couple of pages, briefly explore the principal wild and semiwild natural areas bordering Southern California’s coastal plain. When linked together, these natural areas form a broad, curving crescent around Southern California’s urban population—now more than 20 million strong. About 90% of the hikes found in this book fall into this unpopulated or sparsely populated crescent.

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.

Late-night and early-morning low clouds (the marine layer) typically cover Southern California’s coastline during spring and summer.

The chaparral plant community is commonly found between 1,000 and 5,000 feet in elevation—almost anywhere there’s a slope that hasn’t burned recently. Chaparral needs more moisture than sage scrub, so in the Santa Monicas it’s often found on the shadier, north-facing slopes and other spots protected from the full glare of the sun. The dominant chaparral plants include chamise, scrub oak, manzanita, toyon, mountain mahogany, and various forms of ceanothus (wild lilac). Yuccas, known for their spectacular candle-shaped blooms, often frequent the chaparral zones. The chaparral plants are tough and intricately branched evergreen shrubs with deep root systems that help the plants survive during the long, hot summers. Chaparral is sometimes called elfin forest—a good description of a mature stand. Without benefit of a trail, travel through mature chaparral, which is often

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