Elk Hills and Southern Valley Terraces (Bailey)
Lithology and Stratigraphy
This subsection contains mostly marine Miocene sedimentary rocks in hills at the south end of the Great Valley, nonmarine Plio-Pleistocene sediments in the Elk Hills, and late Quaternary alluvium.
This subsection is on moderately steep to steep hills at the south end of the Great Valley, dissected terraces in the Elk Hills, and nearly level to gently sloping alluvial fans. The fans have nearly level to very gently sloping surfaces and, where they are dissected, moderately steep sideslopes. Some of the terrace remnants are small mesas. The subsection elevation range is mostly from 400 to about 3000 feet, but over 4000 feet in places. Fluvial processes predominate, plus mass wasting in the hills at the south end of the Great Valley.
The soils are mostly Typic Torriorthents on alluvial fans and terraces, plus some Lithic Torriorthents on dissected terrace sideslopes. They are Calcixerollic Xerochrepts, Calcic Haploxerolls, and Typic Argixerolls on hills at the south end of the Central Valley. The soils are well drained. She soil temperature regimes are thermic. Soil moisture regimes are aridic in the Elk Hills and aridic and xeric in hills at the south end of the subsection.
The predominant natural plant communities are Allscale series in the Elk Hills and Needlegrass grasslands in hills at the south end of the subsection.
Characteristic series by lifeform include:
- Grasslands: Alkali sacaton series, California annual grassland series, Creeping ryegrass series, Purple needlegrass series, Saltgrass series.
Shrublands: Allscale series, Arrow weed series, Big sagebrush series, Bladderpod - California ephedra - narrowleaf goldenbush series, Pickleweed series, Shadescale series, Spinescale series, Winter fat series.
The mean annual precipitation is about 5 to 6 inches in the Elk Hills and 6 to 8 inches in hills at the south end of the Central Valley. It is practically all rain in the Elk Hills and mostly rain in hills at the south end of the Central Valley. Mean annual temperature is about 50° to 62° F. The mean freeze-free period is about 225 to 275 days.
Streams in the subsection drain toward the Buena Vista - Kern Lake basin. They are dry most of each year. There are no lakes in the subsection.