Mojave River Valley Museum
Ecological Sections: Sierra Nevada - (MAP)
subsection comprises the very steep eastern slope of the Sierra Nevada
from Eagle Peak west of Bridgeport south to the Tehachapi Pass area.
It includes South Fork Valley of the Kern River system, most of the Scodie
(or Kiavah) Mountains, and Kelso Valley. It has a hot to very cold
and arid to humid climate. MLRAs 22e and 29f.
Lithology and Stratigraphy. Mesozoic granitic predominate
in this subsection, but there are large areas of pre-batholith sedimentary
and metamorphic rocks. Volcanic rocks are sparse; the largest exposure
being Pleistocene basalt and pyroclastic rocks at Crater Mountain on the
west side of Owens Valley, near Poverty Hill. Pleistocene glacial
till and outwash are common in the northern part of the subsection.
Quaternary alluvium is extensive only in Kelso and South Fork Valleys near
the southern end of the Sierra Nevada.
This subsection is characterized by very steep fault-line scarp and steep
mountains. Slopes are gently sloping to moderately steep on Quaternary
volcanic rocks, which are not extensive, and very gently to moderately
sloping on Quaternary alluvial fans and basin floors. Glacial erosion
has modified much of the northern part of the subsection. Cirques,
aretes, cols, and horns are common there. The rivers, except some
of those in glaciated terrain, flow through very steep sided V-shaped
canyons. The elevation ranges about 2500 to 10,000 feet. Faulting,
mass wasting and fluvial erosion are the main geomorphic processes.
The soils are Lithic Torriorthents; Typic and shallow Xeric Torripsamments;
shallow Typic Xeropsamments; Aridic, Torriorthentic, and shallow Entic
Haploxerolls; shallow Typic Cryopsamments; Andic and Lithic Cryumbrepts;
Typic Argixerolls; and Ultic Haploxeralfs. Vitrandic Torriorthents
are common on Crater Mountain. Soils in Kelso and South Fork Valleys
are mostly Xeric Torripsamments and Xerollic Haplargids. The soils
are mostly well drained. Soil temperature regimes are thermic, mesic,
frigid, and cryic. Soil moisture regimes are mostly xeric on the
north to aridic on the south end of the subsection. Soils may have
udic moisture regimes where snow persists through spring, melting to keep
soils moist through much of the summer.
Vegetation. The predominant natural plant communities
northwest of Round Mountain are Jeffrey pine series, White fir series,
Mixed subalpine forest series, and Red fir series, with Big sagebrush series
at lower and communities of Subalpine meadow habitat at higher elevations.
South of about Wonoga Peak, near Owens Lake, they are mainly Singleleaf
pinyon series and lesser amounts of Black bush series. Also, there
are Joshua tree series, California buckwheat series, and Mixed scrub shrublands
at the south end of the Sierra Nevada, and Needlegrass grasslands in South
Characteristic series by lifeform include:
Climate. The mean annual precipitation is about 8 to 50 inches.
Most of the precipitation is snow at higher elevations. Mean annual
temperature is about 35° to 60° F. The mean freeze-free period
is about 25 to 200 days.
Grasslands: Ashy ryegrass series, Montane meadow habitat, Mountain
heather - bilberry series, Nebraska sedge series, Needle-and-thread series,
Rocky Mountain sedge series, Rothrock sagebrush series, Shorthair reedgrass
series, Shorthair sedge series, Subalpine meadow habitat.
Shrublands: Big sagebrush series, Bitterbush series, Black bush
series, California buckwheat series, Greenleaf manzanita series, Joshua
tree series, Low sagebrush series, Parry rabbitbrush series, Rubber rabbitbrush
series, Subalpine upland shrub habitat, Subalpine wetland shrub habitat,
Tobacco brush series.
Forests and woodlands: Aspen series, Jeffrey pine series, Lodgepole
pine series, Mixed subalpine forest series, Piute cypress stands, Red fir
series, Singleleaf pinyon series, White fir series.