Subsection map     Ecological Section map     Previous Subsection     Next Subsection

Subsection M261Fc
Lower Granitic Foothills

This subsection is the lower elevation western edge of the Sierra Nevada from Guadalupe Mountains southeastward to Blue Mountain, west of the Greenhorn Mountains.  It has a hot and subhumid climate.  MLRAs 18d and 18e.

Lithology and Stratigraphy.  Mesozoic granitic rocks predominate in this subsection.  Also, there are some Mesozoic mafic plutonic and Jurassic and older metavolcanic and metasedimentary rocks.  A large body of ultramafic rock is exposed near the Kings River.  There is very little Tertiary sedimentary rock and Quaternary alluvium.

Geomorphology.  This subsection is on moderately steep to steep mountains and hills at the western, or southwestern, foot of the Sierra Nevada.  There is little faulting, compared to the Lower Foothill Metamorphic Belt (M261Fb), and northwest to north-northwest aligned ridges are much less common and less distinct.  Ridges are more commonly aligned toward the southwest, parallel to major rivers that flow off the western slope of the Sierra Nevada.  Alluvial fans, floodplains, and terraces are not extensive.  The subsection elevation range is about 400 to 4000 feet.  Mass wasting and  fluvial erosion are the main geomorphic processes.

Soils.  The soils are mostly Mollic Haploxeralfs; Typic Xerochrepts; and shallow Typic Xerorthents.  Those on ultramafic rocks are mostly Mollic Haploxeralfs.  Typic Chromoxererts and Typic Rhodoxeralfs are common on mafic plutonic rocks, such as gabbro.  The soils are well drained.  Bicarbonate weathering and leaching and accumulation of clay in subsoils are the main pedogenic processes.  Soil temperature regimes are mostly thermic.  Soil moisture regimes are xeric.

Vegetation.   The predominant natural plant community is Blue oak series.   Also, there are some Needlegrass grasslands, Chamise series on shallow and rocky soils, and Valley oak series in valleys.

Climate.  The mean annual precipitation is about 18 to 30 inches.  It is practically all rain.  Mean annual temperature is about 52 to 64  F.  The mean freeze-free period is about 225 to 300 days.

Surface Water.   The San Joaquin, Kings, Kaweah, and Tule Rivers cross this subsection.  Runoff is rapid to these rivers and their tributaries.  All but the larger streams are generally dry during the summer.  There are no natural lakes, but many reservoirs. 


Subsection map     Ecological Section map     Previous Subsection     Next Subsection