LOCATION LEDMOUNT CAEstablished Series
TAXONOMIC CLASS: Medial, amorphic, mesic Lithic Haploxerands
TYPICAL PEDON: Ledmount sandy loam--on a southwest facing slope of about 5 percent. Vegetation at the site is manzanita, grasses and a few scattered black oak, incense-cedar and ponderosa pine. (Colors are for dry soil unless otherwise stated).
Oi--trace; litter and duff.
A1--0 to 7 inches; dark grayish brown (10YR 4/2) sandy loam, black (10YR 2/1) moist; moderate very fine and fine granular structure; soft, very friable, nonsticky and nonplastic; weakly smeary; many very fine roots; many very fine interstitial pores; 10 percent pebbles; slightly acid; clear wavy boundary. (4 to 9 inches thick)
A2--7 to 18 inches; brown (10YR 5/3) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak very fine subangular blocky structure parting to moderate very fine and fine granular; soft, very friable, nonsticky and nonplastic; weakly smeary; many very fine, few fine, medium and coarse roots; many very fine interstitial pores; 10 percent pebbles, 5 percent cobbles; slightly acid, abrupt wavy boundary. (6 to 12 inches thick)
R--18 inches; fractured andesitic tuff breccia.
TYPE LOCATION: NE 1/4, NE 1/4, sec. 27, T. 17 N., R. 11 E., MDBM; 2 miles east of Alpha-Omega Overlook on Highway 20; 1/4 mile east of the turnoff to the Diamond Creek Plantation; 330 feet north of the highway. Nevada County, California.
RANGE IN CHARACTERISTICS: Depth to hard bedrock ranges from 10 to 20 inches. The mean annual soil temperature above the bedrock ranges from 54 to 59 degrees F. The soil moisture control section (the lithic contact) is usually moist all the time from October until late May or June and is dry the rest of the time. Rock fragments are usually about 10 to 25 percent but range from 5 to 35 percent throughout the profile. Base saturation ranges from 10 to 50 percent. 15 bar water to clay ratios range from about 1.2 to 2.0. Bulk density ranges from about 0.85 to 1.0. The A horizon has dry colors of 10YR 4/1, 5/1; 3/2, 4/2, 5/2; 3/3, 4/3, or 5/3. Moist colors are 10YR 2/1, 3/1, 2/2, 3/2, or 3/3. Organic matter ranges from 2 to 6 percent. It is sandy loam or loam and may be gravelly, cobbly or stony. It is moderately acid to slightly acid. The soil is assumed to be dominated by amorphous material based on similar surrounding soils.
In profiles more than 10 inches deep a C horizon may be present. It has dry colors of 10YR 6/3, 6/4, or 5/2. It is moderately acid or strongly acid and is sandy loam with cobbles and pebbles.
COMPETING SERIES: This is the Jahjo series. The Jahjo soils have mean annual soil temperatures that are 47 to 53 degrees F.
GEOGRAPHIC SETTING: Ledmount soils are on gently sloping to very steep mountains and narrow ridge tops at elevations of 2,000 to 6,000 feet. They formed in material weathered from volcanic breccia. Outcrops of breccia are common. The climate has cool moist winters and warm dry summers. Annual precipitation ranges from 35 to 70 inches. Annual snowfall is 0 to 10 inches. Mean annual temperature is 52 degrees F. Average January temperature is 35 degrees F, average July temperature is about 70 degrees F. Frost-free season is about 180 to 230 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Cohasset and McCarthy soils. Both are greater than 20 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well to somewhat excessively drained; medium to very rapid runoff; moderately rapid permeability above the bedrock.
USE AND VEGETATION: Used for livestock grazing. Vegetation is scattered black oak, digger pine, manzanita, canyon oak, ceanothus, grasses, and forbs with stunted conifers in places.
DISTRIBUTION AND EXTENT: Sierra Nevadas of northern California. The soils are moderately extensive.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Nevada County, California, 1981.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ledmount soils were formerly mapped as Iron Mountain series.
Umbric epipedon- the zone from 0 to 7 inches (A1)