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.
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.
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.
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.
Characteristic series by lifeform include:
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.
Grasslands: Ashy ryegrass series, California oatgrass series,
Montane meadow habitat, Needle-and-thread series.
Shrublands: Brewer oak series, Chamise series, Deerbrush series,
Greenleaf manzanita series, Interior live oak series, Tobacco brush series,
Wedgeleaf ceanothus series.
Forests and woodlands: Birchleaf mountain-mahogany series, Black
oak series, Canyon live oak series, Incense-cedar series, Mixed conifer
series, Ponderosa pine series, Giant sequoia series, White fir series.
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.