subsection is the steeper parts of the Diamond Mountains and a high plateau
adjacent to the Diamond Mountains. The climate is temperate to cold
and subhumid. MLRA 22e.
Diamond Mountain - Crystal Peak
Lithology and Stratigraphy. Mesozoic granitic rocks, mostly
hornblende - biotite granodiorite, predominate in this subsection.
There are lesser amounts of Eocene nonmarine sedimentary rocks and post-Eocene
andesite, basalt, rhyolite, and pyroclastic rocks. Some sedimentary
deposits are intercalated with the late Tertiary volcanic rocks.
Geomorphology. This section includes a steep fault-line
scarp, or Honey Lake fault escarpment, and a rolling plateau. The
escarpment is the northeast margin of the Sierra Nevada. It is aligned
toward the northwest, curving around toward the west-northwest at the northern
end. The high plateau is a gently sloping to moderately steep fluvial
erosion surface, some of which has been modified slightly by glaciation.
It is capped by remnants of volcanic rock along the ridge above the Honey
Lake fault escarpment, on Red Rock, Wildcat Ridge, and a few other high
ridges. Indian Creek has cut a deep canyon across the plateau. The
elevation ranges from about 4000 feet along Indian Creek and 4200 at the
bottom of the Honey Lake fault escarpment, to 7738 feet on Diamond Mountain,
7795 feet on Thompson Peak, and 8197 feet on Adams Peak. Faulting,
mass wasting, and fluvial erosion are the main geomorphic processes.
Soils. The soils are mostly shallow Typic and Dystric Xeropsamments;
Typic and Entic Xerumbrepts; and, at lower elevations, Ultic Haploxeralfs.
Those on volcanic rocks are mostly Lithic and Andic Xerumbrepts; Typic
Argixerolls; and Andic Haploxeralfs. The soils are mostly well drained.
Soil temperature regimes are mostly frigid, with some mesic. Soil
moisture regimes are xeric.
Vegetation. The predominant natural plant communities
are Jeffrey pine series and White fir series, and at lower elevations Mixed
conifer series. Small areas of Red fir series are present higher
elevations. Big sagebrush series and Low sagebrush series are common
on very stony and shallow soils in volcanic terrain. The most common
streamside riparian communities are Black cottonwood series at lower elevations
and Mountain alder series at higher elevations. Lodgepole pine series
and Aspen series are common, but not extensive. Sedge meadow communities
occur in wet areas.
Characteristic series by lifeform include:
Climate. The mean annual precipitation is about 20 to 30 inches;
much of it falls as snow. Mean annual temperature is about 35°
to 50° F. The mean freeze-free period is about 25 to 100 days.
Grasslands: Ashy ryegrass series, Green fescue series, Idaho
fescue series, Montane meadow habitat, Nebraska sedge series, Needle-and-thread
series, Rocky Mountain sedge series.
Shrublands: Big sagebrush series, Bitterbush series, Greenleaf
manzanita series, Low sagebrush series, Parry rabbitbrush series, Rubber
rabbitbrush series, Tobacco brush series.
Forests and woodlands: Aspen series, Baker cypress stands, Jeffrey
pine series, Jeffrey pine - ponderosa pine series, Lodgepole pine series,
Ponderosa pine series, Red fir series, Western white pine series, White
Surface Water. Runoff is rapid from most of the area.
There are a few small lakes, or ponds, in glaciated terrain. Streams
on the Honey Lake escarpment drain to Honey Lake. Those on the plateau
west of the escarpment drain through Indian Creek to the Feather River.