The San Gabriel Mountains are a mountain range located in northern Los Angeles
County and western San Bernardino County, California, United States. The
mountain range is part of the Transverse Ranges and lies between the Los Angeles
Basin and the Mojave Desert, with Interstate 5 to the west and Interstate
15 to the east. This range lies in, and is surrounded by, the Angeles National
Forest, with the San Andreas fault as the northern border of the range.
The highest peak in the range is Mount San Antonio, commonly referred to as Mt.
Baldy. Mount Wilson is another famous peak, famed for the Mount Wilson
Observatory and the antenna farm that houses many of the transmitters for
local media. The observatory may be visited by the public. On October 10,
2014, President Obama designated the area the San Gabriel Mountains National
Monument. Geography
Much of the range features rolling peaks. The range lacks craggy features,
but contains a large number of canyons and is generally very rugged and
difficult to traverse. The San Gabriel Mountains are in effect a large fault
block that was uplifted and then dissected by numerous rivers and washes.
= Setting and elevation= The highest elevation, Mount San Antonio
at 10,068 feet, rises towards the eastern extremity of the range which
extends from the Cajon Pass on the east, where the San Gabriel Mountain Range
meets the San Bernardino Mountain Range, westward to meet the Santa Susanna range
at Newhall Pass. North of San Fernando, the San Gabriel
Mountains crest abruptly up to almost 4,000 feet. Pacoima and Big Tujunga
Canyons cut through the range just east of San Fernando, carrying runoff into
the San Fernando Valley. Little Tujunga Canyon Road bridges the range in this
area, connecting the San Fernando Valley to the Santa Clara River valley in the
north. Towering over Big Tujunga Canyon north of Big Tujunga Reservoir is Mount
Gleason, which at 6,502 feet, is the highest in this region of the San
Gabriels. South of the gorge are the southern "foothills" of the mountains,
which rise abruptly 4,000 feet above the Los Angeles Basin and give rise to the
Arroyo Seco, a tributary of the Los Angeles River.
Southeast of Big Tujunga Canyon, the southern front range of the San Gabriels
gradually grows in elevation, culminating in notable peaks such as
Mount Wilson at 5,710 feet. On the north the range is abruptly dissected by the
canyon of the West Fork San Gabriel River. Even further north the range
slopes up into the towering main crest of the San Gabriels, a sweeping
arc-shaped massif 30 miles in length that includes most of the highest peaks
in the range: Waterman Mountain, at 8,038 feet; Mount Islip, at 8,250 feet,
Mount Baden-Powell, at 9,399 feet, Pine Mountain, at 9,648 feet, and finally
Mount San Antonio, the highest peak in the range at 10,068 feet.
On the north slopes of the San Gabriel crest, the northern ranks of mountains
drop down incrementally to the floor of the Mojave Desert in a much more gradual
manner than the sheer southern flank. The Angeles Crest Highway, one of the
main routes across the San Gabriels, runs through this area from west to
east. Little Rock, Big Rock and Sheep Creeks drain off the northern part of
the mountains, forming large alluvial fans as they descend into the Mojave. To
the east, the San Andreas Fault cuts across the range, forming a series of
long, straight and narrow depressions, including Swarthout Valley and Lone Pine
Canyon. South of Mount San Antonio, San Antonio Creek drains the mountains,
cutting the deep San Antonio Canyon. East of San Antonio Canyon, the range
gradually loses elevation, and the highest peaks in this section of the
mountain range are in the south, rising dramatically above the Inland Empire
cities of Claremont, Upland and Rancho Cucamonga. However, there are still
several notable peaks in this region, including Telegraph Peak, at 8,985 feet,
Cucamonga Peak, at 8,859 feet, and Ontario Peak, rising 8,693 feet. Lytle
Creek, flowing generally southwest, drains most of the extreme eastern San
Gabriels. The range terminates at Cajon Pass, through which runs Interstate 15,
and beyond which rise the even higher San Bernardino Mountains.
= Locale= The Range is bound on the north by the
Antelope Valley and the Mojave Desert and to the south by the communities of
greater Los Angeles area. In the western portion of the San Gabriel Mountain
Range, the Sierra Pelona Ridge stretches from approximately Soledad Canyon,
formed by the Santa Clara River. The Sierra Pelona Ridge includes Liebre
Mountain, Sawmill Mountain, Grass Mountain, Redrock Peak, Burnt Peak, most
of which is part of the Angeles National Forest, but also features several rural
communities. = Hydrology=
Melting snow and rain runoff on the south side of the San Gabriels' highest
mountains give rise to its largest river, the San Gabriel River. Just to
the west of Mount Hawkins, a north-south divide separates water running down the
two main forks of the river and their tributaries. The West Fork, beginning at
Red Box Saddle, runs 14 miles eastward, and the East Fork, starting north of
Mount San Antonio, flows 18 miles south and west through a steep, rugged and
precipitous gorge. The two meet at San Gabriel Reservoir, and turn south,
boring through the southern portion of the San Gabriels, emptying out of the
mountains near Azusa into the urban San Gabriel Valley, and eventually to the
Pacific Ocean near Seal Beach. = Peaks=
San Gabriel Mountains peaks within the Angeles National Forest include:
Mount San Antonio, 10,064 ft Pine Mountain, 9,648 ft
Dawson Peak, 9,575 ft Mount Harwood, 9,552 ft
Mount Baden-Powell, 9,399 ft Throop Peak, 9,138 ft
Mount Burnham, 9,001 ft Telegraph Peak, 8,985 ft
Cucamonga Peak, 8,859 ft Ontario Peak, 8,693 ft
Mount Islip, 8,250 ft — site of historic Mt. Islip fire lookout tower
Waterman Mountain, 8,038 ft Iron Mountain, 8,007 ft
South Mount Hawkins, 7,783 ft — lookout destroyed in Curve Fire, 2002
Mount Gleason, 6,502 ft Strawberry Peak, 6,164 ft
San Gabriel Peak, 6,162 ft Vetter Mountain, 5,908 ft — site of
active fire lookout tower Mount Disappointment, 5,960 ft
Vetter Mountain, 5,911 ft — site of historic Vetter Mountain Fire lookout
tower Mount Wilson, 5,710 ft — location of the
Mount Wilson Observatory Mount Lowe, 5,703 ft — site of Mount
Lowe Railway Smith Mountain, 5,111 ft
Mount Lukens, 5,074 ft Echo Mountain, 3,210 ft
Climate The climate of the range is
Mediterranean, with mostly dry summers and cold, wet winters. Snow can fall
above 4,000 feet elevation during frontal passages between November and
April, but is most common in December through March. Annual precipitation
totals are mostly above 25 inches above 3,000 feet elevation, with up to 40
inches falling in some areas above 5,000 feet. The coastal side of the range
receives more precipitation than the desert side. The highest precipitation
is found in the central and eastern parts of the range. Annual precipitation
totals can be extremely high during wet "El Nino" years, sometimes over 70
inches, with single storm totals over 10 inches. Runoff from the mountains during
big storms often produces flooding in adjacent foothill communities. Fires are
a problem during summer and fall, before the rains come, especially during dry
"Santa Ana" wind events. The range is mostly smog free above 5,000 feet
elevation, above the inversion layer. The large telescope installation at Mt.
Wilson is a testimony to the clear atmospheric conditions that prevail,
although light pollution from the L.A. basin below has hindered telescope
activities in recent decades. Geology
Granitic and metasedimentary rocks are the primary constituent of the San
Gabriel Mountains. These rocks, of upper Precambrian to Mesozoic age, are the
remnants of the ancient North American platform that used to reach into
California. Like nearly all of the other mountains in the Transverse Ranges, the
San Gabriels are a series of fault blocks there were uplifted in the
Cenozoic. Ecology
There are both areas of conifer as well as broadleaf forestation, including the
presence of some endemic taxa. Conifer and oak forests are most widespread
above 5,000 feet where the precipitation is above 30 inches. In the wetter areas,
madrone and bay laurel trees also occur in places, and ferns are common. Trees
like willow, alder and cottonwood are also found throughout the range along
the stream courses, even at lower elevations. Chaparral vegetation is
widespread where there is not continuous tall tree cover, especially at lower
elevations. Chaparral is highly adapted to fire, and replaces trees for decades
after fires. There is a subspecies of the Leather Oak which is found only
within the San Gabriel Mountains. The Rift Zone along the San Andreas Fault
produces numerous springs, sag ponds, and wetland areas that are critical
habitat for a variety of native species. Larger animals include mule deer, black
bear, coyote and the rarely seen puma. Smaller mammals include raccoon,
opossum, skunk and bobcats. Golden and bald eagles are found rarely, but hawks
are common. Rattlesnakes are common, and one should be on the lookout for them
when hiking. Transportation
The main road that runs through the San Gabriel Mountains is the Angeles Crest
Highway, State Route 2. It starts in the southwest at the city of La Cañada
Flintridge and ends at its junction with State Route 138, just past Wrightwood,
near the Victor Valley and the West Cajon Valley. Past its junction with
Angeles Forest Highway, traveling east, Angeles Crest Highway features blind
curves, various bumps, and potholes. This section of the "Crest" is closed
during the winter due to rockfall and avalanche hazards. State Route 2, just
past Mountain High, is called the Big Pines Highway all the way to the Route
138 junction. Another key county route which connects
Angelenos to, and through, the mountains is Angeles Forest Highway. Angeles
Forest Highway begins 11 miles northeast of La Cañada Flintridge at its Angeles
Crest Highway junction. Ending near Acton, it allows easy access to the
central Forest and the fast-growing Antelope Valley. Because the "Forest"
and the 11 mile "Crest" portion leading to La Cañada Flintridge is well traveled
by Antelope Valley commuters, its road maintenance is much better, and it is
open much of the winter. State Route 39 connected the city of
Azusa with the Angeles Crest Highway until it was seriously damaged by
landslides, first in 1978, and again in 2005. The highway was opened to
emergency crews in February 2003. The proposed State Route 39 Roadway
Rehabilitation Project would begin five miles north of Crystal Lake Recreation
Area Campground. According to the Caltrans District Seven
"Inside Seven" Newsletter, work will continue through 2009 and 2010 on
reconstruction. As written in the newsletter, "Two projects that will
address those issues and get the highway reopened are scheduled for construction
soon. The first, building two retaining walls near the city of Azusa from Old
San Gabriel Canyon Road to approximately four miles south of SR-2, could begin in
mid-2009. The second, a $45 million project to reconstruct the roadway,
construct soldier pile retaining walls, repair drainage systems, install rock
fall protection, and provide asphalt concrete overlay and traffic striping,
should begin in fall 2010."(source) People heading to Mount Waterman must
now travel west to Pasadena and then travel on the Angeles Crest Highway in
La Canada Flintridge - a nearly two-hour trip. Reopening Highway 39 would cut the
drive-time to the Waterman Ski Area in half and shorten the trip east to
Wrightwood. The segment connecting the Crystal Lake Recreation Area to Route 2
is not scheduled to reopen before 2015. Recreation
In the winter, snowboarding and snow skiing are quite popular in the San
Gabriels, at Mountain High and Mt. Baldy. The two other resorts, Mount
Waterman and Kratka Ridge, are rarely open. In the summer, "canyoneering",
hiking, backpacking, picnicking and camping are some of the activities
popular with visitors. From time to time, a hiker gets lost or stuck on a
mountain ledge, or may fall downhill. Some of the more extreme cases of
emergency search-and-rescue efforts will often be given air time on Los Angeles
television and radio newscasts. The Pacific Crest Trail passes along the
mountain ridge. During the winter, many Southern
California mountaineers climb a variety of snow routes and even some ice routes
in the San Gabriel Mountains. Baldy Bowl is by far the most popular route,
getting hundreds of climbers per season. There are many other routes, offering a
variety of choices. Rock climbing is not as common in the
San Gabriel Range as it is in neighboring areas, as this range is
famous for loose rock. Various faults crisscross the range, making it one of
the steepest and fastest-growing ranges in the world. Plate tectonic activity
breaks up most rock, making it unsuitable for rock climbing. Williamson
Rock was the most famous climbing area, until it was closed for climbing. There
are many other craggy areas scattered about the range that provide mostly
traditional climbing opportunities. Angeles National Forest Fire Lookout
Association has rebuilt and operates Vetter Mountain Lookout, and Slide
Mountain Lookout. The organization is rebuilding South Mount Hawkins Lookout.
Nearby ranges San Rafael Hills
Santa Ana Mountains Verdugo Mountains
San Bernardino Mountains Santa Susana Mountains
Santa Monica Mountains Sierra Pelona Mountains
Tehachapi Mountains References
External links Outdoor LA Hiking Trails – Hiking trails
in the area with maps and directions to the trailheads.
Geographic, Biological, and Geological information