South Valley Alluvium and Basins (Bailey)
Lithology and Stratigraphy
This subsection contains mostly late Quaternary alluvium and lacustrine sediments, but there are small patches of Pliocene or Pleistocene sediments. The alluvium is from rocks in the Sierra Nevada, the Coast Ranges, and the Transverse Ranges.
This subsection is in a level basin and on nearly level to gently sloping alluvial fans surrounding the basin on three sides. The northern part is in the Tulare Basin. The subsection elevation range is from 220 to about 1200 feet. Fluvial and lacustrine processes predominate.
The soils are mostly Typic Torriorthents on alluvial fans, Torriorthents and Typic Natrargids on lake beds, Typic and Vertic Torriorthents and Typic Natrargids on basin-fill around the lake beds, and Typic Haplargids on remnants of old terraces. The soils are well drained. Any soils that were once poorly drained have been drained by diverting and pumping water. The soil temperature regimes are thermic. Soil moisture regimes are aridic.
The predominant natural plant communities are Allscale series on the basin floor and Needlegrass grasslands on alluvial fans. Mesquite series is common in the basin and some Iodine bush series occurs there.
Characteristic series by lifeform include:
- Grasslands: Alkali sacaton series, California annual grassland series, Creeping ryegrass series, Purple needlegrass series, Saltgrass series.
Shrublands: Bush seepweed series, Allscale series, Arrow weed series, Iodine bush series, Pickleweed series, Shadescale series, Spinescale series, Winter fat series.
Forests and woodlands: Mesquite series.
The mean annual precipitation is about 5 to 6 inches; it is practically all rain. Mean annual temperature is about 59° to 62° F. The mean freeze-free period is about 250 to 300 days.
This subsection is a basin that is a sink for water from the southern ends of the Sierra Nevada and the Coast Ranges and from the Transverse Ranges. Water that flows north from the Kern River goes into the Tulare Basin and water that flows south from the Kern River goes to the Buena Vista - Kern Lake Basin. The latter basin contained Buena Vista Lake, at least periodically, before the Kern River was controlled for irrigation. It wet years water from Buena Vista Lake overflowed into Kern Lake. These lakes are now dry. Streams on the alluvial fans, except the Kern River, are dry most of each year.