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The San Gabriel Mountains

As long as humans have lived in the Los Angeles Basin, we have looked at the San Gabriel Mountains. Whether phantomlike behind a veil of brownish haze, sharply etched against a blue winter sky, or playing hide-and-seek with billowing clouds, they are a familiar scene on the northern skyline.

As mountains go, the San Gabriels are a gentle range. Ridgelines are sinuous rather than jagged, summits rounded rather than angular, and slopes tapered rather than sheer. Although they present a formidable barrier to north-south travel, their elevations and topographical features do not compare with the sky-piercing crags of the Sierra Nevada.

The San Gabriels form a great roof over the Southern California coastal lowlands, covering an area that reaches from seaward slopes across to the Mojave Desert and that extends west to east 68 miles from The Ridge Route to Cajon Pass. It can be said that the mountains act as both hero and villain to the Southland’s millions: they protect the coastal plains from the desert’s harshness and gather moisture from Pacific storms, but at the same time they increase urban air pollution by locking in air masses.

Geologists tell us that the range is a massive block of the Earth’s crust, separated from the surrounding landscape by a network of major faults—the San Andreas Fault on the north, the San Gabriel and Sierra Madre Faults on the south, and the Soledad Fault on the west. The great block itself, in turn, is fractured by numerous subsidiary faults. The result is a surface that is extremely uneven. Eons of erosive stream action have cut deep V-shaped canyons, further accentuating the unevenness. The surface rocks are fractured and intermixed in great confusion, forming a heterogeneous mixture of crystalline limestone, schists, and quartzites, which have been invaded by intrusive granites and other igneous rocks, all forming a most complicated mass.

Covering about 80% of this wrinkled mountain mass is a thick blanket of stiff, thorny shrubs and dwarf trees collectively called chaparral: chamise, scrub oak, yucca, wild lilac, mountain mahogany, laurel, snowbrush (whitethorn), chinquapin, and that unpopular champion of all rigidity, manzanita. This elfin forest, where it has not recently been burned off—for it grows quickly back—fastens securely to hillsides, seizing every square foot not preempted by timber or crag. It swarms over hot, exposed slopes whose conditions it alone can endure, spreading until it forms an almost impenetrable collar between the foothills and the high pine country.

Chaparral has been damned as too low to give shade, too high to see over, and too thick to go through. Anyone so foolish as to venture off road or trail and crawl through this brushy maze will soon come to believe that there is a personal hostility in the unyielding branches and scratchy leaves.

A different experience awaits those who consider this elfin forest as a friend to visit, not as an enemy to thrash through. In bloom, much of the chaparral is sprinkled with colorful flowers. And what is more pleasing to the nature lover than ceanothus blooming into misty blue or white, California laurel unfolding masses of yellow flowers, or wild lilac giving forth its sweet aroma after a spring rain? Chaparral is also valuable as a soil cover; where it has been burned off, rain rushes down the hillsides, causing severe erosion on the slopes and flooding in the canyons.

Below the chaparral belt, in the canyons, a luxuriant cover of sycamore, live oak, alder, and bay trees shields sparkling streams from the sun’s glare. Above the chaparral, and sometimes as enclaves within it, is a cool, stately world of conifers: first big-cone Douglas-firs, and then—progressively higher—Jeffrey and ponderosa pines, Coulter pines, incense cedars, sugar pines, white firs, and lodgepole pines. On the highest ridges, subalpine conditions reign, and gnarled limber pines live a marginal existence among windswept crags.

The wildlife of the San Gabriel Mountains is timid—as well it should be. Humans have preempted most of the range, crowding out animals that once roamed in abundance. Some species are gone completely: no longer does the giant California condor soar overhead (although the occasional straggler sometimes wanders over from Ventura County), nor the mammoth grizzly bear prowl the forest. Both disappeared from here shortly after the turn of the 20th century. Often seen in the San Gabriels and in nearby foothill communities is the black bear; naturalists estimate their number to be anywhere from 250 to 300 and they seem to be on the increase. In the remote recesses of the range, an estimated 250 Nelson bighorn sheep scratch out a living, and the population has suffered a steep decline in the past few decades; experts are unsure of the exact causes. You must walk far from the highway to see these noble animals, deep into the rugged San Gabriel and Cucamonga Wildernesses or high up on the stony battlements of Iron Mountain.

The most abundant large mammal in the San Gabriels is the California mule deer, usually yellow-brown in summer, gray in winter, its many-pronged antlers growing to considerable size. Preying on the deer are a growing number of mountain lions, perhaps 40 or 50 in the whole range. In recent years, sightings of these agile beasts have increased, and several well-publicized attacks have occurred. Although the odds of an encounter are slight, hikers should be vigilant, and children should never be left unattended. Smaller mammals include the bobcat, ring-tailed cat, gray fox, weasel, skunk, and a host of squirrels and chipmunks. The region’s most common creature considered sometimes dangerous to humans is the western rattlesnake, abundant below 6,000 feet, and sometimes seen up to 8,000 feet. However, most rattlers are not very aggressive and will move away when approached.

Geographically, the San Gabriels are for most of their length made up of two roughly parallel ranges. The northern, inland range is the longer and loftier, extending from Mount Gleason and Mount Pacifico eastward past the 8,000-foot and 9,000-foot summits of Waterman, Williamson, Islip, Hawkins, Throop, and Baden-Powell, and climaxing near its eastern end in the only summit over 10,000 feet—Mount San Antonio (Old Baldy) and its cluster of satellite peaks. The southern, or front, range, though neither as long nor as high, is equally as rugged. Two of its summits—Strawberry and San Gabriel—exceed 6,000 feet, and 10 others exceed 5,000 feet. Below the peaks is a complex of deep, shaded canyons, extending well up into the higher parts of the range. The range’s major watershed is the San Gabriel River, whose three main forks and countless tributaries drain fully 20% of the mountain precipitation. Other important watersheds are Pacoima, Little Tujunga, Big Tujunga, Arroyo Seco, Santa Anita, San Antonio, and Lytle Creek Canyons on the south slope of the range, and Little Rock and Big Rock Creeks on the north.

Mountain lion near Chilao

Finally, there is the Liebre Mountain–Sawmill Mountain–Sierra Pelona country to the northwest of the San Gabriels proper, beyond the great wind gap of Soledad Canyon. Geographers disagree on whether this gentle mountain region of long whale-backed ridges and shallow canyons belongs to the San Gabriels, the Tehachapis, or to neither. But it is part of Angeles National Forest and it is good hiking country, so it is included here.

Other mountain ranges in California are higher, more jagged, more bedecked with ice and snow, more breathtaking, or more primitive. But no other is so accessible to so many people for so little effort—and year-round. When winter’s white mantle closes off the high country, the woodsy canyons and green-velvet foothills become refreshing, delightful, and inviting. And then, in turn, when summer’s sweltering dryness invades canyon and foothill, the high mountains once again beckon. For this all-season aspect, and for the San Gabriels themselves—ageless, rock-ribbed, and aromatic with the restoring scents of forest and chaparral—shall we ever be thankful.