Tehachapi Mountains

Vorlage:Geobox

The Tehachapi Mountains (Vorlage:IPAEng) are a short transverse range in southern California in the United States, running SW-NE connecting the Coast Ranges on the west with the southern end of the Sierra Nevada mountains on the east. The range extends for approximately 40 mi (64 km) SW-NE in southern Kern County southeast of Bakersfield and vary in height from approximately 4,000 ft (1,220 m) to 8,000 ft (2,440 m).

Tehachapi, Double, and Covington Mountains
Telephoto of the Sierra Crest
Sierra Crest from Cummings Mountain

Description

The range forms a barrier separating the San Joaquin Valley to the northwest and the Mojave Desert / Great Basin to the southeast. The range is crossed by Tejon Pass at its southwestern end (providing the route for Interstate 5). The dramatic incline of Interstate 5 on the northern slopes of this mountain range, downhill to the San Joaquin Valley floor, is regionally referred to as The Grapevine because of the grapevines still found on the earlier route on the mountain slope next to the highway. (Sometimes this colloquial name is extended to describe the portion of Interstate 5 on the southern slopes of the mountain range as well, which drops into Santa Clarita, California and the Los Angeles metro area.)

The less geographically dramatic Tehachapi Pass, found on State Route 58, is at its northeastern end. It is also crossed by the California Aqueduct, which supplies water from the Sacramento-San Joaquin Delta to Southern California. The Los Angeles Aqueduct flows along the southern edge of the mountains. The Tehachapi Loop provides a major railroad link across the mountains and is considered an engineering marvel.

The Tehachapis, though neither a long nor high mountain range as California mountain ranges go, are regarded by many Californians as the dividing feature that separates northern California from southern California (though some contend that southern California extends as far north as the Fresno area). Because the Ridge Route auto highway was constructed across these mountains and the ranges south of it in the early 20th century, many historians say California averted a potential split into two separate states - North California and South California. (There have in fact been two distinct periods of California history where this split has been discussed in the legislature, in 1860 and 1965, and both proposed the crest of the Tehachapi Mountains as the new border. Both proposals, of course, failed.)

The Monolith cement works, which supplied cement for the construction of Hoover Dam, among other major public works, is situated in the Tehachapis east of Tehachapi Pass.

Geology

The Tehachapis are largely the result of the movements of the Garlock Fault, located along the southern base of the range, a major transform fault which runs from the San Andreas Fault in the west to the Sierra Fault on the east and some distance beyond. This fault is unusual in California in that it is a left-lateral fault; that is, its motion is opposite to most of the faults in the state which are right-lateral faults.

Flora and fauna

There are at least 68 bird species found in the Tehachapi Mountains, all of which consume acorns of the California Black Oak as part of their diet.^[1] Other flora found here include the buckbrush and mountain mahogany. As expected in California mountains, large fauna include mule deer, mountain lion, coyote, fox, black bear, feral pig, bobcat and racoon. The forests are primarily oak in the savannah with the mountains featuring conifers. Some of the rare or unique species include incense cedar, white fir, and in a few remote locations, small stands of quaking aspen.^[2]

Climate

The range is in an interesting crossroads among climate zones. The Great Basin to the east and southeast typically receives just a few inches of precipitation a year, usually in winter. Summer monsoon season can bring localized torrential rains to parts of the range as well. To the south and southwest lie the main Transverse Ranges in the Los Padres National Forest and Angeles National Forest. The prevailing wind is southwesterly, funneling through Tejon Pass and into the east-west canyons and valleys of the Tehachapi range with regularity. To the northwest lies the San Joaquin Valley with its oak savanna climbing the broad western slopes of the range. Like sand dunes piling up where winds converge, the Tehachapis collect marine and valley moisture, which piles up into fog that blankets the range many weeks of the year. Like Sicily is to Italy, the Tehachapi crest is a subalpine island at the toe of the Sierra Nevada, which dominates the northern skyline. The higher north-facing (subalpine) slopes are mixed conifer, black oak and scrub oak, while the south-facing (continental) are live oak, scrub and Gray Pine (Pinus sabaniana), typical of the relationship between the moisture-retaining northern slopes and the year-round exposed southern slopes. The area surrounding the Tehachapi Crest is semiarid, including the sage country of the Tehachapi Pass area. Canyons, even on southern slopes, however, can have year-round water flows, particularly when orographic enhancement has squeezed extra precipitation from passing storms and snowmelt during the spring months.

Panoramic view of the Tehachapi Mountains.