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Southern California’s

Wilderness Rim

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 15 feet high and incredibly dense from the ground up, is almost impossible.

A touch of the southern oak woodland and riparian woodland communities is present in the Santa Monicas and sparsely distributed nearly everywhere else in coastal Southern California. The Santa Monica Mountains include the southernmost stands of the valley oak, a massive, spreading tree that is as much a symbol of the Golden State as are the redwoods farther north. The southern oak woodland is very parklike in appearance, especially in the spring when attended by new growth of grass and wildflowers. Riparian (streamside) vegetation includes trees such as willows, sycamores, and alders that thrive wherever water flows year-round—typically along the bottom of the larger canyons. Strolling through the riot of growth in riparian zones is the nearest thing to a jungle experience you can have in arid Southern California. Both types of habitat have declined all over California as a result of urbanization and agricultural development, and the attendant exploitation of water resources.

Wildfire plays a dominant role in the ecology of the Santa Monica Mountains, and indeed almost everywhere else in coastal Southern California. Sage scrub and chaparral vegetation readily renews itself after fire. Before modern times wildfires would incinerate most hillsides every 5–15 years, and thick stands of chaparral seldom developed. Over the past century, however, the active prevention and suppression of fires has led to longer growth cycles and abnormally large accumulations of deadwood. Once started, today’s wildfires in chaparral zones are often difficult or impossible to control.

Toyon (California holly, the “holly” of Hollywood) is a common chaparral plant.

From Malibu east into L.A.’s west side, the Santa Monicas are steadily filling up with custom houses and subdivisions, all of which are in jeopardy from firestorms during the dry summer and fall seasons. Large and small wildfires will forever torment those who seek to establish permanent residence here.

Today the Santa Monicas are a patchwork quilt of private lands (many already built upon or slated for future development) and public lands, protected from urban development by inclusion within Santa Monica Mountains National Recreation Area, a unit of the national park system.

Jeffrey pines in the Laguna Mountains

The San Gabriel Mountains

Turning our attention farther north and east, we find the San Gabriel Mountains, another segment of the east-west-trending Transverse Ranges. Behind the south ramparts of the San Gabriels, whose chaparraled slopes rise sheer from the Los Angeles Basin and the San Gabriel Valley, stands a series of high peaks, the tallest of which—Old Baldy, also known as Mt. San Antonio—exceeds 10,000 feet in elevation. Yawning gorges slash into the range, in one place offering more than a mile of vertical relief between canyon bottom and adjacent ridge.

Geologists figure that the San Gabriels are being squeezed horizontally about a tenth of an inch each year, and being thrust upward much more rapidly than that. Caught in this tectonic frenzy, the San Gabriel Mountains are surging upward as fast as any mountain range on the planet. They are also disintegrating at a spectacular rate. Although the San Gabriels consist mainly of durable granitic rocks, much like those in the sturdy Sierra Nevada, the San Gabriel rocks have been through a tectonic meat grinder. The tops of the San Gabriels are fairly rounded, but their slopes are often appallingly steep and unstable. An average of 7 tons of material disappears from each acre of the front face each year, most of it coming to rest behind debris barriers and dams in the L.A. Basin below.

The San Gabriel Mountains themselves are relatively young as upthrust units—only a few million years old. This is not true of the ages of most of the rocks that compose them. Some rocks exposed here are representative of the oldest found on the Pacific Coast—more than 600 million years old.

Botanically, parts of the San Gabriel Mountains are extremely attractive, especially in zones above 4,000 feet that receive enough precipitation. There the coniferous forest, which has two phases in Southern California, thrives. The yellow pine phase includes conifers such as bigcone Douglas-fir, ponderosa pine, Jeffrey pine, sugar pine, incense-cedar, and white fir, and forms tall, open forest. These species are often intermixed with live oaks, California bay (bay laurel), and scattered chaparral shrubs such as manzanita and mountain mahogany. Higher than about 8,000 feet, in the lodgepole pine phase, lodgepole pine, white fir, and limber pine are the prevailing trees. These trees, somewhat shorter and more weather-beaten than those below, exist in small, sometimes dense stands, interspersed with such shrubs as chinquapin, snowbrush, and manzanita.

Excluding relatively small parcels of private land, the bulk of the higher San Gabriel Mountains lies within Angeles National Forest. Hundreds of square miles of wilderness or near wilderness in the San Gabriels are available within easy reach of millions of L.A. residents.

The 2009 Station Fire devastated the western portion of the San Gabriel Mountains, charring more than 160,000 acres. More than three years later, many affected areas remain closed to aid recovery, while others are open but will be scarred for decades.

The San Bernardino Mountains

Farther east, across the low gap of Cajon Pass, the Transverse Ranges soar again as the San Bernardino Mountains. With Lake Arrowhead, Big Bear Lake, and winter ski areas, the mid-elevations of the San Bernardinos (5,000–8,000 feet in elevation) draw millions of day-trippers and vacationers annually. Hikers and backpackers can explore the 10,000-foot-plus peaks of the San Gorgonio Wilderness, including 11,500-foot San Gorgonio Mountain itself—Southern California’s high point. There it is possible to ascend through the yellow-pine and lodgepole belts to treeline and above.

As in the San Gabriel Mountains, islands of private land in the San Bernardinos are surrounded by large sections of national forest. San Bernardino National Forest encompasses much of the San Bernardino Mountains, as well as the San Jacinto and Santa Rosa Mountains to the south.

The most dramatic change taking place in the high mountains of Southern California—especially the San Bernardinos —is a massive die-off of coniferous trees. The high-elevation areas in Southern California have been receiving less precipitation in recent decades. A string of very dry years beginning in 1998–99 triggered an acute infestation of bark beetles, which eventually resulted in sudden death for millions of drought-stressed pine, fir, and cedar trees. Wildfires in October 2003 and 2007 destroyed millions of these dead and dying trees, and many others are being removed by logging operations in an overall effort to thin the forest to attain a more healthy level of tree density.

The Mojave Desert

North and east of the San Gabriel and San Bernardino Mountains lies the vast, arid sweep of the Mojave Desert, a zone only partly included in this book. The Mojave, sometimes known as the high desert for its generally high average elevation, becomes far less populated and more diverse in its natural features as we move toward eastern California. A few of the hikes in this book explore the transitional region between high mountain and high desert.

Joshua tree woodland, Mojave Desert

There, at elevations of 3,000–5,000 feet, thrives the pinyon-juniper woodland, largely characterized by the rather stunted looking one-leaf pinyon pine and the California juniper. Large sections of the Mojave, again in the elevation range of about 3,000–5,000 feet, are dominated by Joshua tree woodland. Here the indicator plant is an outsized member of the yucca family—the Joshua tree. Joshua Tree National Park preserves some, but hardly all, of the finest stands of these odd, tree-sized plants.

The San Jacinto Mountains

Moving south from the San Bernardino Mountains and Joshua Tree National Park, we find the northwest-southeast-trending San Jacinto Mountains and their southerly extension, the Santa Rosa Mountains. These lofty ranges comprise the northern ramparts of what geologists call the Peninsular Ranges—so named because they extend, more or less continuously, south across the Mexican border and comprise the spine of the long, thin peninsula of Baja California.

As the highest peak in the entire Peninsular Ranges province, 10,800-foot San Jacinto Peak would outrank all other Southern California peaks were it not for the slightly higher San Gorgonio massif looming just 20 miles north. For sheer dramatic impact, however, San Jacinto wins hands down. Viewed from I-10 outside Palm Springs, the north and east escarpments of San Jacinto appear to rise nearly straight up from the desert floor—10,000 feet in 10 miles or less. Every plant community we have mentioned so far except Joshua tree woodland thrives at one level or another on the mountain.

San Jacinto’s pine-clad western slopes shelter several resort communities (such as Idyllwild); otherwise nearly all of the mountain’s upper elevations lie within national-forest wilderness or state wilderness areas.

The Colorado Desert

East of the northernmost Peninsular Ranges lie Palm Springs, the Coachella Valley, and the Salton Trough (Salton Sea). They are within the domain known as the Colorado Desert—California’s low desert—so called because it stretches west from the lower Colorado River, which divides California from Arizona. A 1,000-square-mile chunk of the Colorado Desert lies within Anza-Borrego Desert State Park, by far the largest state park in California. Especially close and convenient for San Diegans, Anza-Borrego’s vast acreage ranges from intricately dissected, desiccated terrain known as badlands to the pinyon-juniper and yellow-pine forests of the Peninsular Ranges.

Lord’s candle yucca ranges from the coast to the desert rim.

The Laguna, Cuyamaca, Palomar, and Santa Ana Mountains

East and north of San Diego, the Peninsular Ranges consist of a number of parallel ranges—primarily the Laguna, Cuyamaca, and Palomar Ranges—each attaining heights of a little more than 6,000 feet. Chaparral blankets the slopes of these mountains, while the typical yellow-pine assemblage of oak, pine, cedar, and fir dominates the higher elevations. Farther north and west, bordering the rapidly expanding urban zones of southwestern Riverside and southern Orange County, lie the Santa Ana Mountains. They are the northernmost coastal expressions of the Peninsular Ranges.

Oak woodland shelters Cole Creek, Santa Rosa Plateau Ecological Reserve (Hike 70).

Suburban sprawl has crept into the foothills of these far-southern ranges, and in some cases threatens to degrade the higher elevations as well. Fortunately, large parts of this mountainous region lie within the jurisdiction of Cleveland National Forest and various state parks.

All the mountain ranges rimming San Diego have been hard-hit recently by both drought and catastrophic wildfire. The 300,000-acre Cedar Fire, which blazed an elongated path across central San Diego County in October 2003, burned through primarily chaparral and oak woodland, and secondarily through prime oak and coniferous forest, mostly in the Cuyamaca Mountains. The chaparral and oak woodlands of lower elevation, adapted to periodic fires, have largely recovered. The formerly lush Cuyamaca Mountains may never look quite the same, however, unless the climate shifts back to a wetter regime.