subsection is the southern end of the Sierra Nevada. It includes
most of the Tehachapi and Piute Mountains. It has a hot to cold and
semi-arid to subhumid climate. MLRAs 18e and 22d.
Tehachapi - Piute Mountains
Lithology and Stratigraphy. Mesozoic granitic rocks
predominate in this subsection, but there are some areas of pre-batholith
metamorphic rocks. There is a large area post-batholith volcanic
rocks, mostly Miocene and Pliocene, on and around Emerald Mountain.
Quaternary alluvium is extensive in Walker, Tehachapi, Cummings, and Bear
Geomorphology. This subsection is characterized by
steep mountains. Many ridges are slightly elongated with many different
orientations, but those in the Piute Mountains are generally aligned near
north-south and those in the Tehachapi Mountains are generally aligned
near east-west. There is a small area of rolling plateau surface
above 6000 feet in the Piute Mountains. Slopes are gently sloping
to moderately steep on Quaternary volcanic rocks, which are not extensive,
and nearly level to moderately sloping on Quaternary alluvial fans and
basin floors. The elevation ranges from about 3500 up to 7981 feet
on Double Mountain in the Tehachapi Mountains and 8318 feet in the Piute
Mountains. Mass wasting and fluvial erosion are the main geomorphic
Soils. The soils are mostly Typic and Pachic Haploxerolls
and Lithic and Typic Argixerolls. There are Umbrepts at higher elevations
in the Piute Mountains, but they are not extensive. Soils are mostly
Xeric Torripsamments and Xeralfic Haplargids in Walker Basin and Mollic
Xerofluvents and Typic and Pachic Argixerolls in the other large valleys.
The soils are well drained. Soil temperature regimes are mostly thermic
and mesic, but frigid at the highest elevations. Soil moisture
regimes are mostly xeric, but aridic in Walker Basin.
Vegetation. The predominant natural plant communities
are Blue oak series, and Singleleaf pinyon series on the southeast edge
of the subsection and north of Walker Basin. Canyon live oak series
is common on very steep rocky slopes and Mixed chaparral shrublands are
common on shallow soils. There is some Ponderosa pine series on Breckenridge
Mountain and some Jeffrey pine series and White fir series in the higher
parts of the Piute and Tehachapi Mountains. Black oak series and
Valley oak series are common on mountain footslopes and in valleys.
Characteristic series by lifeform include:
Climate. The mean annual precipitation is about 12 to 30 inches.
Most of the precipitation is snow at higher elevations. Mean annual
temperature is about 42° to 56° F. The mean freeze-free period
is in the range from 75 to 175 days.
Grasslands: California annual grassland series, Montane meadow
Shrublands: Brewer oak series, Chamise series, Deerbrush series,
Greenleaf manzanita series, Interior live oak series, Tobacco brush series,
Wedgeleaf ceanothus series.
Forests and woodlands: Birchleaf mountain-mahogany series, Black
oak series, Blue oak series, Canyon live oak series, Fox pine series, Jeffrey
pine series, Piute cypress stands, Ponderosa pine series, Singleleaf pinyon
series, Valley oak series, White fir series.
Surface Water. Runoff is rapid from most of the area.
It flows to the Kern River or to closed basins in the southern end of the
Great Valley or in the Mojave Desert. All streams are dry through
the summer. There are no natural lakes or ponds in the subsection.