Subsection map     Ecological Section map     Previous Subsection     Next Subsection

Subsection M261Ep
Lower Batholith

This subsection comprises the mid-elevations of the western slope of the Sierra Nevada from El Portal on the Merced River southwest to the Greenhorn Mountains.  It has a temperate and humid climate.  MLRAs 22d and 22e.

Lithology and Stratigraphy.   Mesozoic granitic, mainly adamellite and granodiorite,  and pre-batholith rocks predominate in this subsection.  The pre-batholith rocks are metamorphosed Jurassic rocks and older metavolcanic and metasedimentary rocks.

Geomorphology.   This subsection is mostly on steep slopes along the lower, or southwest, edge of the extensive Sierra Nevada plateau, and on steep mountains in the Greenhorn Mountain range.  Several large rivers from the Merced to the Kings Rivers cross the subsection.   These rivers and some of their tributaries flow in the bottoms of very steep sided canyons.  The canyon of the Kings River is about 4000 feet deep where it enters this subsection.  The elevation ranges from about 3000 feet, or less along the Kings River, to about 6500 feet.  Mass wasting and fluvial erosion are the main geomorphic processes.

Soils.  The soils are mostly Dystric and shallow Dystric Xerochrepts; Ultic Haploxeralfs; and Entic Ultic, Pachic, Pachic Ultic, and shallow Entic Haploxerolls on granitic rocks.  Also, Dystric Lithic Xerochrepts; Haploxerolls; and Typic Haploxerults are common on metamorphic rocks.   The soils are mostly well drained.  Soil temperature regimes are mostly mesic.  Soil moisture regimes are xeric.

Vegetation.   The predominant natural plant communities are Ponderosa pine series at lower elevations and Mixed conifer series at higher elevations.  In deep canyons, Canyon live oak series is common on very steep rocky slopes and Manzanita chaparral and Mixed chaparral shrublands are common on shallow soils.  Most of the groves containing the Giant sequoia series occur in this subsection.

Climate.  The mean annual precipitation is about 30 to 60 inches; much of it falls as snow.  Mean annual temperature is about 45° to 55° F.  The mean freeze-free period is in the range from 100 to 150 days.

Surface Water.  Runoff is rapid; it flows to the Merced, San Joaquin, Kings, Kaweah, Tule, or Kern Rivers or tributaries of them.  Maximum flow in these rivers is during spring when snow is melting rapidly.  There are no natural lakes, but there are some reservoirs. 


Subsection map     Ecological Section map     Previous Subsection     Next Subsection